3.4: Patterns of Biodiversity - Biology

3.4: Patterns of Biodiversity - Biology

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3.4: Patterns of Biodiversity

Ecological Mechanisms that Contributes to Biodiversity

A number of simple and complex ecological mechanisms contribute to biodiversity. According to one view, the so – called local or deterministic view, the biodiversity is determined principally by biological interactions such as competition and predation.

The other view considers the importance of other environmental factors such as soil type, moisture, temperature, gradient, productivity, niche and habitat diversity and some other factors like stability, disturbance, immigration, extinction and species differentiation and movement at the regional level and the interaction between local and regional processes.

Thus, there are a variety of determinants of species richness, some of which are discussed below.

1. Competition:

The ecological effects of inter specific competition are too many. These effects, however, depend on the scale of competition. On a small scale we can observe the co-occurrence of only a few species with complementary ecological niches but on a broad scale the community will contain more species, occurring within a patchwork, with each patch supporting only a few. In nature, competition is often avoided by differential resource utilization, e.g., different species of fish feeding at different depths.

When exotic animal or plant species are introduced to a new habitat, they sometimes prove to be better competitors and many indigenous species suffer. For example, introduction of common carp to some reservoirs of Punjab and elsewhere has adversely affected the native populations of major carps.

In brief, the significance of inter specific competition depends on how widespread are its evolutionary and ecological consequences. Inter specific competition tends to affect communities and their biodiversity in many ways some of which are less understood even today.

2. Predation:

Predation affects both prey populations and whole ecological communities. When predation promotes the coexistence of species among which there would otherwise be competitive exclusion, this is called predator- mediated coexistence. The effect of predation on a group of competing species depends on which species suffer most. If it is subordinate species, then these may be driven to extinction and therefore the total number of species in the community will decrease.

However, if dominant species suffer most, heavy predation will create space and resources for other species, consequently species numbers may then increase. The numbers of species in a community are usually maximum at intermediate levels of predation.

The effects of predation on biodiversity have been extensively studied in aquatic systems, in which the introduction of a predatory fish, starfish or salamander can greatly change the community structure of primary producers and consumers (carpenter et al. 1987,1988). The effect of herbivore on plant species diversity has also been studied.

The pest pressure hypothesis suggests that seedlings are most dense close to the parent tree, but their survival is maximum at a distance from the parent, because herbivores will be more common among the dense seedlings adjacent to parent tree. Several authors suggested that herbivore promotes more diversity in tropical forests (Clark and Clark, 1984).

3. Productivity:

Nutrient input and productivity affect biodiversity. Plant productivity often depends on the nutrient or condition which is most limiting to growth. Animal productivity also depends on resource levels and some other key factors such as temperature and moisture (for terrestrial environments) and temperature, dissolved oxygen and depth for aquatic systems. However, these are not the only factors that affect productivity.

It was suggested by Connell and Orias (1964) that biodiversity should be highest in relatively stable habitats having high productivity. This is called productivity-stability hypothesis (Tilman,1982). Tilman and Pacala (1993) suggested that biodiversity does not increase monotonically with productivity for any group of species, but that species richness varies depending on what environmental factor is used as a measure of productivity and which species are being taken into consideration.

It has been also suggested that predator-prey ratios increase with the increase in productivity. However, at high productivity levels, predators consume a disproportionate share of the available production, thereby causing a decline in community biodiversity. The intertaxon competition hypothesis (Rosenweig and Abramsk 1993) holds that the peaks of species diversity for different multispecies taxa should occur in areas showing different productivity levels. But, Tilman’s (1982) hypothesis suggested that habitat heterogeneity increases with productivity to a certain point only after which it decreases. However, increase in biodiversity with productivity is not a universal phenomenon.

4. Spatial Heterogeneity:

Spatially heterogeneous habitats offer a wide spectrum of resources and food chains. Accordingly, they are expected to support more species as they provide a greater variety of microhabitats (spatial niches), a greater range of microclimates, more types of places to hide from predators and a greater variety of trophic niches.

Gould and Walker (1997) have shown a positive relationship between number of vascular plant species and index of spatial heterogeneity (ranging from 0 to 1), based on a number of things including soil pH, slope, drainage pattern and substrate types. There are several studies indicating a positive relationship between animal species richness and plant spatial heterogeneity.

5. Climate:

The effects of climatic variation on species richness depend on whether the variation is unpredictable or predictable. In seasonally changing environment, different species may occur at different times of the year. Therefore, more species may be expected living together in a seasonal environment than a completely constant one.

For example, in temperate regions different annual plants germinate, grow, flower and produce seeds at different times during a seasonal cycle. However, there is no firm relationship between species richness and climatic instability. Stable climate is likely to support more species. Tropics often showing better climatic regulation are richer in species than temperate regions.

6. Harshness of Environment:

An environment may be called harsh or extreme if organisms are unable to live there. However, some organisms do occur in very cold and very hot environments and grossly polluted rivers and lakes. But the distribution pattern of organisms generally indicates that species richness is quite lower in harsh environments. Many studies have indicated that diversity of benthic macro-invertebrates and fish was quite low in streams and lakes having low pH.

Most caves and hot springs also exhibit low biodiversity. The deepest parts of the oceans (200 m to 8000 m) also have few species of fish such as tripod fish and lizard fish adapted to living in complete darkness, low temperature and very high pressures, some of them showing interesting specialization of eyes and luminous organs.

7. Disturbance:

Many communities experience periodic physical disturbance. Anthropogenic activities that alter habitat characteristics also affect local species diversity. The intermediate disturbance hypothesis (Connell, 1978) suggested that communities are expected to have more species when the frequency of disturbance is neither too high nor too low. This hypothesis was proposed to account for patterns of species richness in tropical rain forests and coral reefs.

In upland streams disturbances are created by a number of factors including water diversion for fishing or other purposes and quarrying. These activities affect indigenous fish species, benthic invertebrates and riparian vegetation. Sometimes flash floods with enormous gushing waters carrying tons of silt load play havoc with the natural communities as the entire river bed is destroyed and boulders and fish species are washed off by speedily flowing water (Singh and Badola, 1980, Sharma and Singh 1980). Disturbance by municipal sewage also affects biological diversity (Nautiyal et al 1996,2000).

Townsend et al (1997) observed that the pattern of richness of macro-invertebrate species conformed with the intermediate disturbance hypothesis. Disturbances often keep the community in early stages of succession and therefore poor diversity.

8. Other Factors:

Other factors and mechanisms that affect biodiversity are community succession, latitudinal gradient, altitudinal gradient and depth, immigration, emigration, extinction, and evolutionary age (time) and evolutionary adaptations.

The communities may differ in species diversity because some are closer to ecological or evolutionary equilibrium and others are still evolving. For example, tropics are richer in species than temperate regions because, among other things, tropics have existed over long periods of evolutionary time, whereas the temperate regions are still recovering from the Pleistocene glaciations.

Latitudinal gradients of diversity are quite obvious, species of plants, and animals increasing toward the equator. For example, within a small region at 60° north latitude one might found 10 species of ants at 40°, there may be 50 to 100 species and in a similar area within 20° of the equator, between 100 to 200 species (Ricklefs and Miller, 2000).

Diversity in marine environments follows a similar trend. This increase in diversity from the poles to the tropics has been attributed to a number of factors including greater predation, productivity, light, temperature and water regimes.

Altitudinal gradients (Singh and Nautiyal 1990) and depth also affect species richness. In hillstreams, low diversity of macro-invertebrates was observed at higher altitudes. In terrestrial environments, a decrease in species richness with altitude is a widespread phenomenon.

Bird, mammal and vascular plant species richness declined with the increase in altitude in Himalayan mountains of Nepal (Hunter and Yonzon, 1992 Whittaker,1977). Singh and Kumar (2003) found no fish species in Garhwal hillstreams at high altitudes (2400 to 3600 m). Number of species of phytoplankton, zooplankton and fish also tend to decline with increasing depth in the ocean.

Isolation and extinctions have also played their role in affecting species richness in different parts of this earth. The extinctions of many large animals in the Pleistocene may reflect the role of human migration. It is well known that over the past 30,000 to 40,000 years, a major loss of animal biodiversity has occurred over Australia, North America, New Zealand and Madagascar.

Biodiversity: Meaning, Types, Evolution, Factors and Measures

The biosphere (the web of life that lives within and depends upon the inorganic spheres) constitutes a vital life support system for man and its existence in a healthy and functional state is essential for the existence of human race.

It is the presence of innumerable organisms, the biological diversity, which makes our life pleasant and possible.

The term biodiversity was coined by Walter and Rosen (1985) and is the abbreviated word for Biological Diversity. Life originated on earth almost four billion years ago and nature took more than 1 billion year to develop this wide and complex spectrum of life on earth. Scientists believe that the total number of species on earth is in between 10-80 million (Wilson 1988) of which 1.4 million species have been enlisted so far.

However, we are losing this heritage of millions of years at a very fast rate. The reduction in diversity in life forms is bound to have grave consequences for the entire living world. It has become extremely important to study simultaneously the various life forms on earth and the causes of their destruction. Biodiversity is the total variety of life on our planet.

The total number of races, varieties or species i.e., the sum total of various types of microbes, plants and animals present in a system is referred to as biodiversity. The word biodiversity is now very widely used not only by the scientific community, but also by the common people, environmental groups, conservationists, industrialists and economists. So it is very important to have clear idea about the definition of biodiversity which is recognized as a separate scientific discipline with its own principles.

Some of the Important Definitions of Biodiversity are given here:

(i) Biodiversity is the variety of life in all its forms, levels and combinations. It includes species diversity, genetic diversity and ecosystem diversity (International Union for Conservation of Nature and Natural Resources—IUCN, United Nations Environment Programme—UNEP and World Wildlife Fund—WWF 1991).

(ii) United Nations Earth Summit in Rio de Janeiro defined biodiversity as – The variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part. This includes diversity within species, between species and of ecosystems.

(iii) According to U.S. Congressional Biodiversity Act – Biological Diversity is the variety and variability among living organisms and the ecological complexes in which they occur and encompases ecosystem diversity, species diversity and genetic diversity.

(iv) In the simplest terms, biological diversity is the variety of life and its processes and it includes the variety of living organisms, the genetic differences among them and the communities and ecosystems in which they occur. In this article we will present some fundamental aspects of biodiversity and its conservation.

Types of Biodiversity:

Biodiversity is usually studied at three different levels—Species diversity, Genetic diversity and Ecosystem diversity.

(i) Species Diversity:

Evolution of species diversity has probably been possible because of habitat diversity on earth. It refers to the variety of species within a region. This diversity could be measured on the basis of number of species in a region. The term biodiversity is commonly used as a synonym of species diversity.

It actually refers to species richness, in terms of number of species in a site or habitat. Global diversity is typically represented in terms of total number of species of different taxonomic groups. As mentioned before, an estimated 1.4 million species have been identified to date. Species diversity, again, is studied at three levels: alpha diversity (number of species coexisting at a site), beta diversity (difference in species complement between patches) and gamma diversity (number of species in a large area, e.g. a country).

This series can further be extended to delta diversity for biomes (biomes are climatically and geographically defined areas of ecologically similar climatic conditions such as communities of plants, animals and soil organisms and are often referred to as ecosystems) and omega diversity for the entire biosphere.

Some authors call it taxon diversity (variety of taxa within a community of an area). It is generally studied at the species level and hence called species diversity. When the taxonomic levels such as genus and family are considered, the term taxon diversity is more appropriate. This term is similar to taxic diversity.

(ii) Genetic Diversity:

Within a species there are a number of subspecies, varieties (subspecies and varieties are recognizable morphological variations within a species), forms (form is generally used to recognize and describe sporadic variations in a single morphological feature) or strains which slightly differ from each other.

These differences are due to slight variations in their genetic organization. This diversity in the genetic make-up of a species is referred to as genetic diversity. A species with a large number of varieties or strains is considered to be rich and diverse in its genetic organization. Genetic variations arise in individuals of a species by genie or chromosomal mutations. Genetic variation within populations is considered a “prerequisite for adaptation and evolutionary change”, and as such an important aspect of biodiversity.

Genetic variation is often expressed in terms of alleles (genes occupying the same locus in a chromosome) and is mainly studied at the population level. Genetic variations can be measured by different recent techniques such as allozyme analysis, DNA fingerprinting, polymerase chain reaction, restriction site mapping and DNA sequencing.

Diversities go on increasing at the micro level. Differences in the level of varieties are followed by differences among the subspecies, varieties and species. Accumulation of these differences at infra-specific level will automatically lead to distinctive character at the species level.

(iii) Ecosystem Diversity:

In ecosystem, there may exist different land-forms, each of which supports different and specific vegetation. Ecosystem diversity in contrast to genetic and species diversity is difficult to measure since the boundaries of the communities which constitute the various sub-ecosystems are not distinct. Ecosystem diversity could best be understood if one studies the communities in various ecological niches within the given ecosystem, each community is associated with definite complexes.

These complexes are related to composition and structure of biodiversity. Loss of ecosystem diversity may be considered as ultimate cause of loss of species and genetic diversity. Community diversity is a synonym of ecosystem diversity and is defined as the diversity of community types within larger areas (ecological, units). It should not be confused with habitat variety which is an expression mainly used for different species of animals which have different habitats.

It has been observed and reported that there is no direct effect of the number of species on ecosystem processes. The effect on the ecosystem arises from functional differences between species. It is suggested that ecosystem with lots of functional traits will operate more efficiency in terms of productivity, resilience and resistance to invaders.

Consequently, it was suggested (Hooper, 1998) that functional diversity should be measured in a species pool that summarizes the extent of functional differences. In simple form, functional diversity is the range of functions that are performed by organisms in a system.

The species within a habitat or community can be divided into different functional types such as feeding guilds or plant growth forms or into functionally similar taxa such as suspension feeders or deposit feeders. Functionally similar species may be from quite different taxonomic entities. A common measure of functional diversity is the number of functional groups represented by species in a community.

To cluster species into functional groups, first a set of characters significant for ecosystem functioning is measured for each species obtaining a trait matrix. The trait matrix is then converted into a distance matrix. Finally, the distance matrix is clustered with standard multivariate methods to divide species among functional groups.

Evolution of Biodiversity:

Biodiversity is created by evolutionary and ecological processes. The ecology describes patterns of and provides explanations for the biodiversity of extant ecosystems. Ecological processes also have evolutionary consequences. They interact with genetic diversity via adaptation, microevolution and speciation.

The environment provides continual pressures to diversify via adaptation, innovation and exploitation of new ways of life. The species diversity is the most conspicuous result of ecological and evolutionary processes driving the multiplication of species. Ecological factors like age of the ecosystem, environmental gradient, isolation, nature of physical environment, architecture of the habitat, interaction between species, natural disturbance, migration and dispersal of a species.

Darwin (1859) proposed that species compete and only the fittest survive in nature. It is inferred that under a strong pressure of natural selection the less fit species are eliminated. From this concept has arisen the competitive exclusion principle (Hardin 1960), which is based on the idea that no two species can be exactly equally fit. It states that if two or more species exist in the same habitat, ultimately all but one of them will be excluded. This is the paradox of biodiversity: we expect few species but we find many in nature.

Mechanisms that may be Responsible for Preventing Loss of Species by Competitive Exclusion, and Allow Species Diversity to be Maintained are as follows (Newman 2000):

(1) Each species has an exclusive ecological niche and subjected to conditions where it is fitter than its competitors.

(2) A perfect balance is maintained between species loss and gain. The slightly less fit species are eliminated by competitive exclusion, but this process is so slow that there will be time for other species to arise by evolution or to invade from other region.

(3) Competition is reduced or prevented, because the main controls on abundance are physical disturbance, stresses (e.g. low temperature, toxic substances), predation and disease, hence competitive exclusion does not occur.

Factors that Promotes High Diversity:

Biodiversity varies greatly from site to site, over both large and small distances (Huston 1994). This variation is due to certain factors that we discuss here.

(i) Favourable Environmental Conditions:

It is quite natural to think that species diversity would be greater where the conditions for growth are very favourable for plants and animals. But this is not universally true. Curriae (1991) studied the numbers of species of trees, mammals, birds, reptiles and amphibians across the USA and Canada in relation to environmental conditions. Species richness of each group showed positive correlation with temperature and solar influx.

In relation to these two factors biodiversity increases with increasing favourableness. The results from the long-term Park Grass Experiment at Rothamsted, England, showed that the more favourable the nutrient regime for plant growth — the lower was the biodiversity. Grime (1973) proposed the highest diversity at intermediate stress or favourableness. Therefore, it can be inferred that there is no universal relationship between species-diversity and the prevalence of favourable condition.

(ii) Reducing Soil Fertility:

There is a negative relationship between diversity and soil fertility (Newman, 2000). It is necessary to reduce soil fertility to achieve high species diversity in grasslands. The low diversity in high productivity grasslands is because a few species grow tall, there is intense competition for light and low growing species are eliminated.

(iii) Disturbance:

Minor disturbances help to maintain local species diversity. Disturbance of forests by felling of trees, fires affects the subsequent species composition. Grazing animals in grasslands can be considered disturbance and they can increase diversity. In the past tropical rainforests had been used for shifting cultivation.

The diversity was initiated as a response to such disturbance. The present day forest represent a mosaic of small patches at different stages of succession following disturbance that provides niches and contributes to diversity (Connell 1979). The conclusion is that disturbance can augment biodiversity and diversity managers need to consider carefully what disturbance to allow or introduce.

(iv) Heterogeneity of the Environment:

Environmental heterogeneity increases β-diversity but has no such effect on α-diversity (Newman 2000). On a landscape scale patches and mosaics of varying vegetation can be related to differences in exposure, steepness, soil depth, wetness, rock type affecting soil properties and other factors of microclimate and soil.

Each species responds differently to the environmental factors and so the proportions of species change. Whittaker (1956) showed that each woody species in the Great Smoky Mountains had a different distribution to altitude and exposure. So if we want to promote p-diversity we should pay attention to heterogeneity in the physical environment.

(v) Plant Species Diversity may Promote Insect Diversity:

High plant diversity may promote insect diversity. This is primarily because of coevolution between plants and insects involving secondary chemicals (Harborne 1993). The most of the secondary chemicals in plants such as alkaloids, terpenoids and flavonoids, are poisonous to most animals.

However, there are examples where one insect species being tolerant to one secondary chemical. This gives the insect the ability to eat something that most other insects cannot eat and it may then specialize in eating one plant species. Thus many insects eat only one or a few plant species. Other herbivorous animals tend to show less specificity in their diet. They show preferences between plant species but rarely confine their feeding to one plant species. Thus plant species diversity is likely to promote diversity of insects, but not necessarily of other animals.

Measures of Biodiversity:

Biodiversity can be measured in different ways. Two main factors taken into account when measuring diversity are richness and evenness. Species richness is the number of different species present in an area. However, diversity depends not only on richness, but also on evenness. Evenness compares the similarity of the population size of each of the species present. Evenness is a measure of the relative abundance of the different species making up the richness of an area.

Let us consider, two communities, A and B of species 1 and 2, both with 100 individuals:

The species richness of community B would equal that of community A. However, community B has more evenness than A. Community B must be considered more diverse: one is more likely to get both species there than m community A. A community dominated by one or two species is considered to be less diverse than one in which several different species have a similar abundance. As species richness and evenness increase, the diversity increases.

Study shows cloud patterns reveal species habitat

A new NASA study found that variations in cloud cover sharply delineated the boundaries of ecological biomes relevant to many unique species.

Much of Earth&rsquos biodiversity is concentrated in areas where not enough is known about species habitats and their wider distributions, making management and conservation a challenge. To address the problem, scientists at the University at Buffalo and Yale University used NASA satellite data to study cloud cover, which they found can help identify the size and location of important animal and plant habitats.

Clouds influence such environmental factors as rain, sunlight, surface temperature and leaf wetness&mdashall of which dictate where plants and animals can survive. As part of their study, researchers examined 15 years of data from NASA&rsquos Earth-orbiting Terra and Aqua satellites and built a database containing two images per day of cloud cover for nearly every square kilometer of the planet from 2000 to 2014.

The study found that variations in cloud cover sharply delineated the boundaries of ecological biomes relevant to many unique species.

The study was published in the journal PLOS Biology on March 31.

&ldquoWhen we visualized the data, it was remarkable how clearly you could see many different biomes on Earth based on the frequency and timing of cloudy days over the past 15 years,&rdquo said lead scientist Adam Wilson, who conducted the majority of the research at Yale University and is now an assistant professor of geography at the University at Buffalo. &ldquoAs you cross from one ecosystem into another, those transitions show up very clearly, and the exciting thing is that these data allow you to directly observe those patterns at 1-kilometer resolution.&rdquo

Cloud cover also helped the researchers better predict where specific species live. By taking cloud patterns into account, the team was able to determine the size and location of habitats for the montane woodcreeper (a South American bird) and king protea (a South African shrub) in unprecedented detail and accuracy. That finding is particularly exciting because the technique could be used to research the habitats of threatened plants and animals, said co-author Walter Jetz, associate professor of ecology and evolutionary biology at Yale University.

&ldquoUnderstanding the spatial patterns of biodiversity is critical if we want to make informed decisions about how to protect species and manage biodiversity and its many functions into the future,&rdquo Jetz said.

The study demonstrates how remote sensing can be a powerful tool in those efforts, Wilson said. &ldquoThat&rsquos one of the really exciting developments in the field today. We now have decades of satellite observations that we can pull together to characterize the global environment,&rdquo he said, noting that Aqua and Aura have been collecting two images per day everywhere on Earth for well over a decade. &ldquoIt is exciting to now be able to tap into this large stack of detailed data to support global biodiversity and ecosystem monitoring and conservation.&rdquo

Related links:

Looking back, is there a project that your lab pursued that stands out for you as particularly inspiring, tough, or simply memorable?

In 2013, we synthesized for the first time our knowledge about tropical African plant biodiversity. Leaning on the massive digitization effort of plant specimens for numerous participating herbaria and a consortium of several African botany experts, we generated a high quality open access mega database called RAINBIO. RAINBIO contains to date over half a million African plant specimens representing distribution information for over 25,000 plant species [6]. This biodiversity synthesis exercise allowed us to address numerous questions about the current state and conservation of African tropical plant biodiversity [7,8,9], and especially rain forests. We are now using this database and modeling approaches to understand how tropical vegetation will respond to climate change across tropical Africa by the end of this century. The project was tough because we were dealing initially with thousands of records that needed to be sorted, quality checked, and validated. We generated automated scripts to deal with this mass of information, which was then checked by the experts to ensure the database is as accurate as possible. This was inspiring because it highlighted the vital role of taxonomists and experts. The availability of masses of online biodiversity data gives the impression that all is known and perfect, but the reality is that biodiversity data need to be constantly updated, curated, and validated, which is part of the taxonomists’ work. Now more than ever we need to continue efforts to discover and describe biodiversity around us, especially in high biodiversity regions such as the tropics.

Organization and Policies

  1. Classroom Presentations: The course meets three times a week. Class topics are outlined in the attached schedule.

An integral part of this course is the development of critical thinking skills. Biology is a dynamic science that requires more than mere acquisition and memorization of facts. It requires conceptualization of core concepts in order to understand the interrelationships of life from the subcellular level to the whole organism. It's my challenge to bring to my teaching the critical thinking, rigor, creativity, and spirit of experimentation that defines research itself. In short, you will not memorize, but instead will be practicing "real science" in my classroom. It is my goal that you, my students, emerge with a firm grasp of the nature of science so that you can appreciate basic research, think critically about real world issues, problems and situations, find your niche in the sciences (one based on passion), and sustain a lifelong curiosity about the world around you.

I will assume you have read the assigned material before entering class. I strongly suggest that you participate in a study group, and use the group to assess your comprehension of the course material. I also urge you to utilize the Penn State Lehigh Valley Learning Center where our teaching assistant, Foram Dave, will be holding routine tutor sessions.

I will provide instruction in the nuts and bolts of appropriate experimental methods. I also will provide guidance into how an effective experiment is designed. You , however, will perform your own experiments. You as the researcher must plan and carry out every step of your experimentation. What I am stressing is that you think about the experiments you are carrying out , plan ahead, and follow through with your results and write-ups.

Each student will be required to write a scientific protocol. You will be required to follow the guidelines in the manual Writing in the Biology Curriculum (Dunski et al., 1994), which is on reserve in the library. For your protocol, you will have the opportunity to make two revisions prior to receiving your grade.

Legitimate excuses are the following:

  1. illness, with a doctor's excuse and receipt
  2. a University-sponsored event (including religious holidays recognized by the University)
  3. a death in the family with documentation
  4. during Finals Week three or more exams in one day

Family reunions, anniversaries and weddings are not legitimate excuses and make-up exams will not be given for those reasons. Check the exam schedule now to see if there are any conflicts between your academic and social calendar, and make adjustments or arrangements in your social calendar right away.

* It is stressed that if you are late for class or miss class because of dangerous weather conditions, your safety is more important. Always drive safely.

If you fail to make up a missed lab you will lose 100 of your total laboratory points at the end of the semester. Missed labs will indeed affect your grade!

Institute for Biodiversity Science & Sustainability

Based in San Francisco, the Institute for Biodiversity Science and Sustainability is home to more than 100 research scientists and nearly 46 million scientific specimens from around the world—nearly 40,000 of which are alive and on display in the Academy’s Steinhart Aquarium. The Institute also leverages the expertise and efforts of the Academy's aquarium biologists and more than 100 international Research and Field Associates and 450 distinguished Fellows.

Through expeditions around the globe, captive breeding programs, and investigations in the lab, the institute’s scientists strive to understand the evolution and interconnectedness of life. Through these same efforts, as well as through partnerships, community outreach, and public engagement initiatives, the institute aims to guide critical conservation decisions and address the challenge of sustainability.

Future Directions: Linking Principles to Patterns Based on Fine-Scale Movement Paths

In this review, we contextualize bat movements in the general conceptual framework of movement ecology (Nathan et al. 2008). We have specified some of the unique features that bats have evolved in relation to their movement ecology. We have also highlighted some benefits and disadvantages of specific motion and navigation capacities for bats. Further, we have outlined some of the consequences that underlying mechanisms impose on bat-resource interaction, on their sociality, and on disease dynamics. Movement ecology has progressed over the past decade because of concurrent advances in technologies allowing new types of empirical studies alongside synthesis across disciplines that together provide emergent insights that define the movement ecology paradigm. Technical advances do not only include molecular methods such as genotype sequencing or stable isotopes but, most significantly, the technology for tracking movements on fine temporal and spatial scales (Bridge et al. 2011). The biggest challenge for tracking animals using remote telemetry has always been the limits on the size of devices that could be attached. There is a tradeoff between accuracy of positioning and battery life/weight, i.e., the more accurate the device (GPS precision) and the longer it can record, the heavier it is (Bridge et al. 2011 Kays et al. 2015). Recently, 1–3 g tracking units became available that allow users to monitor the movement of a bat weighing less than 30 g, which means that many of the migrating medium-sized bat species (e.g., Lasiurus cinereus, Nyctalus noctula) could in principle be tracked through a complete migration if the tagged animal is recaptured and the unit retrieved (Weller et al. 2016). Many research areas, such as the aforementioned studies on bat-plant interactions, bat sociality, and disease transmission, among others, look forward to the adoption of these rapidly evolving techniques. We envision the following exciting questions that may be answered by linking the proximate and ultimate causes of bat movement:

Linking morphology to motion capacity and fitness. What is the scope of intraspecific variation in wing morphology, and its consequences for motion capacity and fitness? We observe large intraspecific variation of wing morphology in bat species (Norberg and Rayner 1987), yet it is not known whether this morphological variation has consequences for individuals with respect to foraging, social behavior, and individual fitness. Miniaturized GPS tags will help in the future to shed light on how individual motion capacity related to morphology may facilitate or impair certain feeding behaviors, foraging success, and migration capacity, leading ultimately to intraspecific variation in reproductive fitness.

Linking strategic fuel choice to motion capacity and landscape-scale movements. Which fuel types are optimal for responding to daily and seasonal fluctuations in resource abundance, particularly in context to phenotypic plasticity of digestive organs? Powered flight is energetically costly. Moreover, because bats appear to be constrained by the mammalian blueprint (i.e., no exclusive use of endogenous fuel sources for sustained flight), they may be constrained in the length and duration of daily movements. Fuel use may also influence population connectivity in naturally or anthropogenically fragmented landscapes if certain landscape features, such as cities or lakes, present barriers, i.e., when distances exceed capacity to sustain flights without refueling over inhospitable terrain.

Understanding the context-dependent use of sensory cues for the navigation capacity of bats. How are different sensory cues used hierarchically in bat orientation and navigation? The role of magnetic sensing for movement in familiar and unfamiliar terrain is of particular interest. Current evidence suggests the existence of an iron-based magnetic sense, yet the location and structure of this sensory system remains unknown. Also, it is unknown how the hierarchy of sensory modalities change when bats switch from familiar to unfamiliar terrain, or when available cues change during diel or seasonal cycles. A multidisciplinary approach has been adopted to solve similar questions in bird navigation, involving molecular biology, chemistry, quantum physics, and neurobiology (Holland 2014). A similar approach will undoubtedly prove fruitful in bat navigation.

Understanding the influence of navigation capacity on bat sociality. What is the influence of inadvertent public cues on bat sociality? The audible nature of bat echolocation calls (audible at least to other bats) seems to have consequences for bat sociality, yet atmospheric attenuation may limit the use of echolocation calls for eavesdropping conspecifics. Our current understanding of how physical features of bat vocalizations are propagating or limiting certain social systems is incomplete. Further, how much do intraspecific variations of navigation capacity affect bat sociality? Recent studies have shed light on intraspecific variation in echolocation calls and other vocalizations of bats, but our knowledge how such variation might foster certain social tactics remains largely unknown. Our current understanding is hampered by a lack of data on how navigation capacity varies across individuals and whether intraspecific (e.g., sex-specific) variation may influence movement strategies and social behaviors.

Understanding the consequences of the navigation capacity of bats for the interaction with food items on the landscape level. What is the influence of bat movements on antagonistic interactions with their prey and mutualistic interactions with plants? Recent studies highlight the strong interaction between insect-feeding bats and their insect prey, which can be seen as a textbook example of an arms race between a consumer and its prey. Current studies focus on details of this interaction in a 1∶1 situation, yet consequences for insects and plants (or bats) on the population or landscape level are yet to be discovered. There is also strong evidence pointing out that fruit and flower availability might even influence the occurrence of migration, nomadism, territorialism, and central place foraging in various bat species. Those variations in movement strategy in response to food availability might be better understood in the light of novel analytical frameworks (e.g., Abrahms et al. 2017).

Linking motion capacity to pathogen transmission risk. How does bat movement affect the spread of pathogens and risk of spillover? Studies of bat movements and disease have been limited by the weight of tags (Hayman et al. 2013). Therefore, little is known about how bat pathogens spread and persist in bat populations in time and space. Improved tag technologies may soon permit better estimation of both local (within colony) movements and broad-scale migratory movements in ways that will further our understanding of transmission and disease dynamics in bat hosts. Coupling empirical estimates of bat movements with modeling of disease dynamics will be crucial for predicting risk of spillover from bat populations serving as viral reservoirs as well as assessing impacts from emerging diseases such as white-nose syndrome.

Future studies on bat movements hold promise to confirm and challenge current hypotheses about the biology and ecology of this diverse group of mammals. We anticipate that novel technologies, such as on-board sensors, will challenge many conclusions that were once considered to be established textbook wisdom, thus broadening not only our understanding of bat movement ecology but providing novel insights into general biological and ecological processes. Conversely, conceptual advances in movement ecology should inform how we study bat movements to provide new integrative insights into ecological processes and patterns, including biodiversity (Jeltsch et al. 2013). Thus, we foresee a productive future in the study of bat movements, particularly for studies that combine both underlying principles and derived patterns.

Christian C. Voigt wishes to thank the German National Science Foundation (DFG) for financial support of the International Berlin Bat Meeting: Movement Ecology of Bats (DFG-VO890/27). This study was also partly funded by the BioMove Training Group (DFG-GRK 2118/1) and a priority program (DFG-SPP 1596) to Voigt. Marco A. R. Mello was funded by the Minas Gerais Research Foundation (FAPEMIG: APQ-01043-13 and PPM-00324-15) and the Alexander von Humboldt Foundation (AvH: 3.4-8151/15037). Raina K. Plowright is supported by the U.S. National Institute of General Medical Sciences IDeA Program (P20GM103474 and P30GM110732), Montana University System Research Initiative (51040-MUSRI2015-03), DARPA (D16AP00113), and SERDP (RC-2633).

High School Science - Distance Learning Resources for Students

Welcome! In light of the COVID 19 pandemic and school closures, we have worked with our partnering districts to create and curate distance learning resources for students.

The following resources were developed by district science TOSA teams and the Portland Metro STEM Partnership (PMSP) Physics, Chemistry, and Biology Councils. These Councils represent curriculum development leads and master HS teachers from Beaverton, Hillsboro, and Portland Public. Thank you, district science leaders and PMSP Content Council leaders, for developing this set of distance learning resources for high school students!

Background: The Patterns High School Science Sequence is a three-year course pathway and curriculum aligned to the Next Generation Science Standards (NGSS). The sequence consists of freshman physics, sophomore chemistry, and junior biology courses.

Looking for the in-person materials to use during hybrid teaching? Click Here

NGSS alignment information for each unit can be found on the first page of the virtual resource google documents.

Student materials are available to the public. Teacher materials, such as answer keys, require permission and verification that you are an educator to maintain security for the answer keys.

Students may use either the virtual resource or the print resource. There is no need for students to access both.

Timeline - We will update the website as resources in development become available.

Print Resources - A 20-page (10 sheet) packet will be produced for each unit. Numerous Portland Metro STEM partner districts plan to print these resources and distribute them via nutrition centers during the school closure.


Unit 1 - Patterns & Inquiry

Unit 2 - Texting & Driving

Units 3 & 4 will not be taught for CDL. Their standards have been incorporated into later units.

Unit 5 - Waves & Technology

Unit 6 - Electricity, Power Production, and Climate Science

Unit 7 - Space & the Universe


Unit 1 - KMT & Climate Change

Unit 2 - Atoms & the Periodic Table

Unit 3 - Nuclear Chemistry

Unit 4 - Bonding & Intermolecular Forces

Unit 5 - Chemical Reactions & Stoichiometry

Unit 6 - Stoichiometry


Unit 1 - Ecosystems & Biodiversity

Unit 2 - Biomolecules

Unit 3 - Cells to Organisms

Unit 4 - Genomics

Unit 5 - Evolution

Unit 6 - Climate Change & Ecosystem

Biodiversity: Facts and figures

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Laura Hood summarises the latest data on the world's biodiversity, with facts and figures on its value and efforts to conserve it.

This feature contains the latest data on the extent and the distribution of the world's biodiversity. It also includes the most recent estimates of extinction threats for different groups of species, as well as facts and figures on the value of biodiversity and efforts to conserve it.

The data are based mostly on the best available sources, including Conservation International, the UN Food and Agriculture Organization, the 2009 Red List of Threatened Species published by the International Union for Conservation of Nature (IUCN), the WWF's Living Planet Report, and the Earth Trends database of the World Resources Institute.

Readers will notice that although the majority of the world's biodiversity is found in the developing world, most data have been collected and analysed in institutions based in richer countries.

Thankfully, several international initiatives are underway to build the biodiversity data-gathering capacity of research institutions in developing countries and to connect them to efforts in the developed world. These include the Global Biodiversity Information Facility and the Proteus project of the UNEP World Conservation Monitoring Centre in the United Kingdom .

What is biodiversity?

Biodiversity (or biological diversity) is a collective term meaning the totality and variety of life on Earth. Biodiversity includes genetic diversity within species, the variety among species, and the range of ecosystems within which life exists and interacts.

How many species?

Estimates of the number of species on Earth vary from 3 million to 100 million. The UN Convention on Biological Diversity says there are some 13 million species, of which 1.75 million have been described ([1] and see below). A more updated figure comes from an analysis of the IUCN's 2008 Red List of Threatened Species (the issue is not addressed in the 2009 Red List) which states that 1.8 million species have been described out of an estimated 5 million to 30 million in existence. [2]

Number of described species on Earth
Species Number
Bacteria 4,000
Protoctists (algae, protozoa) 80,000
Animals &ndash vertebrates 52,000
Animals &ndash invertebrates 1,272,000
Fungi 72,000
Plants 270,000
Total described species 1,750,000
Possible total of all species (including unknown species) 14,000,000
Source: UNEP/Global Environment Outlook ( Ref 3 )

Where is biodiversity greatest?

Generally, species density is greatest in the Southern Hemisphere.

Seventy per cent of the world's species is found in just 12 countries: Australia, Brazil, China, Colombia, Costa Rica, the Democratic Republic of Congo, Ecuador, India, Indonesia, Madagascar, Mexico and Peru. The entire Hindu Kush&ndashHimalayan belt has an estimated 25,000 plant species, comprising 10 per cent of the world's flora. [3]

Tropical regions support two-thirds of the estimated 250,000 plant species. The highest tree diversity recorded to date is 1,200 species in a 52-hectare plot in Lambir Hills National Park, Sarawak (Malaysian Borneo). [4] Overall, tropical rainforests are thought to contain 50&ndash90 per cent of all species. [5] Some 2,600 bird species (about 30 per cent of the total) depend on tropical forests.

Vascular plant species*
Country Number
Australia 15,638
Brazil 56,215
China 8,200
Colombia 32,200
Congo, Democratic Republic 11,007
Costa Rica 12,119
Ecuador 19,362
India 18,664
Indonesia 29,375
Madagascar 9,505
Mexico 26,071
Peru 17,144
Source: World Resources Institute, Earth Trends ( Ref 5 )
* A vascular plant is one whose tissues conduct fluids

Bird species dependent on tropical forests
Region Number
Latin America 1,300
Africa 400
Asia 900
Total 2,600
Source: World Resources Institute ( Ref 5 )

What is a 'biodiversity hotspot'?

A biodiversity hotspot is an area of rich biodiversity that faces serious threats to its existence. The concept was developed by environmental scientist Norman Myers of Oxford University in the United Kingdom in an attempt to identify priority areas for biodiversity conservation. [6] The best-known proponent of the hotspots thesis is the US group Conservation International, which has produced a map of hotspots on the basis of their plant diversity and the impacts upon them. In addition to harbouring at least 1,500 endemic plant species, hotspots must also have lost more than 70 per cent of their original natural vegetation.

Ninety-eight per cent of Madagascar's land mammals, 92 per cent of its reptiles, 68 per cent of its plants and 41 per cent of its breeding bird species exist nowhere else on Earth. [7] Sixty per cent of the plant species endemic to Ecuador's Galapagos Islands are threatened with extinction, as are 75 per cent of the endemic plant species of the Canary Islands. [8] Twenty-five biodiversity hotspots contain 44 per cent of all plant species, and 35 per cent of all terrestrial vertebrate species exist in only 1.4 per cent of the planet's land area.

Hotspots at a glance
Area Original hotspot area (sq km) Hotspot area today (sq km) Protected area (sq km) Total plant species Total terrestrial vertebrate species Endemic bird species under threat Endemic mammal species under threat Endemic amphibians
under threat
Extinct species since 1500*
Atlantic Forest 1,233,875 99,944 50,370 20,000 1,509 55 21 14 1
Brazilian Cerrado 2,031,990 438,910 111,051 10,000 1,027 10 4 2 0
California Floristic Province 293,804 73,451 108,715 3,488 566 4 21 8 2
Cape Floristic Region 78,555 15,711 10,859 9,000 514 0 1 7 1
Caribbean Islands 229,549 22,955 29,605 13,000 1,195 48 18 143 38
Caucasus 532,658 143,818 42,721 6,400 595 0 2 2 0
Chilean Winter Rainfall Valdivian Forests 397,142 119,143 50,745 3,892 335 6 5 15 0
Coastal Forests of Eastern Africa 291,250 29,125 50,889 4,000 1,085 2 6 4 0
Guinean forests of West Africa 620,314 93,047 108,104 9,000 1,315 31 35 49 0
Indo-Burma 2,373,057 118,653 235,758 13,500 2,221 18 25 35 1
Madagascar and Indian Ocean Islands 600,461 60,046 18,482 13,000 849 57 51 61 45
Mediterranean Basin 2,085,292 98,009 90,242 22,500 945 9 11 14 5
Mesoamerica 1,130,019 226,004 142,103 17,000 2,245 31 29 232 7
Mountains of Southwest China 262,446 20,996 14,034 12,000 940 2 3 3 0
New Caledonia 18,972 5,122 4,192 3,270 184 7 3 0 1
New Zealand 270,197 59,443 74,260 2,300 242 63 3 4 23
Philippines 297,179 20,803 32,404 9,253 939 56 47 48 2
Polynesia and Micronesia 47,239 10,015 2,436 5,330 372 90 8 1 43
Southwest Australia 356,717 107,015 38,379 5,571 521 3 6 3 2
Succulent Karoo 102,691 29,780 2,567 6,356 395 0 1 1 1
Sundaland 1,501,063 100,571 179,723 25,000 1,601 43 60 59 4
Tropical Andes 1,542,644 385,661 246,871 30,000 2,904 110 14 363 2
Tumbes-Chocó-Magdalena 274,597 65,903 34,338 11,000 1,502 21 7 8 4
Wallacea 338,494 50,774 24,387 10,000 1,091 49 44 7 3
Western Ghats and Sri Lanka 189,611 43,611 26,130 5,916 865 10 14 87 20
Source: Conservation International ( Ref 6 )
* Endemic species of terrestrial vertebrate

What is extinction?

A species is classified as extinct if a single individual member cannot be found despite exhaustive surveys over a long period of time. This summarises the definition used by the IUCN, which compiles the periodic Red List of Threatened Species . A species being pronounced as extinct is not always the last word, however. The Vietnam warty pig ( Sus bucculentus) , for example, was listed as extinct in 1996. However, it was reclassified following the discovery of a fresh skull the following year. One mammal, the Bavarian pine vole ( Microtus bavaricus) , was rediscovered on the Germany&ndashAustria border in 2000. It had previously not been seen since 1962. [9]

What are the current rates of extinction?

The current rate of species extinction is many times higher than the 'background' rate, which has prevailed over long periods of geological time. The background extinction rate varies, but estimates based on the fossil record suggest that in mammals and birds, one species has been lost every 500 to 1,000 years. [10]

According to Global Environment Outlook 4, species extinction is occurring at 100 times the natural rate, and is expected to accelerate to between 1,000 and 10,000 times the natural rate in the coming decades. [11] The IUCN says that the current rate of extinction may already be as high as 10,000 times the natural rate (

What is 'mass extinction'?

The permanent loss of large numbers of species over a relatively short period of geological time is known as a mass extinction. According to the fossil record, there have been five historical mass extinctions (see table below). The reasons for these are often related to changes in the Earth's environment and atmosphere. Many scientists now believe that the Earth is facing a sixth mass extinction, in part because of human activities.

Mass extinctions
Extinction period Cause and effects
Late Cambrian

Why is biodiversity threatened?

The leading threats to biodiversity are: converting land to agriculture, clearing forests, climate change, pollution, unsustainable harvesting of natural resources, and the introduction of so-called alien species to areas where they are not native. [3] The importance of each factor varies geographically. But one study of animal extinctions since the year 1600 found that 39 per cent arose mainly from the introduction of alien species, 36 per cent from habitat destruction, and 23 per cent from hunting or deliberate extermination. [13] Secondary causes of biodiversity loss include human population growth, unsustainable patterns of consumption, increasing production of waste, urban development and international conflict. [3]

How many species have become extinct recently?

At least 803 species have become extinct since the year 1500, according to the IUCN's 2009 Red List of Threatened Species. [9] The 2004 version put this figure at 784.

The actual number of extinctions may be higher still as many extinctions have either not been detected or belong to a taxonomic group that has not been evaluated by the Red List. For example, the Global Amphibian Assessment recently added 29 extinct species to the list. By comparison, the 2000 edition of the Red List of Threatened Species identified 766 species that have become extinct, and the 1997 edition identified 380 species.

The numbers of mammals and insects can show a decline in extinctions in the Red List of Threatened Species between years. This is because of changes to the way extinctions are classified, or because species are now known to have become extinct before 1500, rather than through their rediscovery.

Species extinct (or extinct in the wild)
Extinct Extinct in wild Total
Mammals 76 2 78
Birds 133 4 137
Reptiles 20 1 21
Amphibians 37 2 39
Fishes 90 13 103
Subtotal 356 22 378
Extinct Extinct in wild Total
Insects 60 1 61
Crustaceans 7 1 8
Molluscs 295 14 309
Others 1 0 1
Subtotal 363 16 379
Extinct Extinct in wild Total
Mosses 2 0 2
Ferns 3 0 3
Gymnosperms 0 4 4
Dicots 77 22 99
Monocots 2 2 4
Subtotal 84 28 112
Grand total Extinct Extinct in wild Total
803 66 869
Source: Red List of Threatened Species 2009 ( Ref 9 )

How many species are threatened with extinction?

The 2008 Red List of Threatened Species states that the number of species threatened with extinction is 16,928. This includes one in four mammals, one in three amphibians, and one in eight birds.

The number of threatened species is increasing. In 2000, the Global Biodiversity Outlook, published by the UN Convention on Biological Diversity, reported that 11,046 species are threatened with extinction. These included vertebrates (such as mammals, birds and fishes), invertebrates (such as insects) and plants.

One of the reasons for the increase, however, is that the criteria for listing have changed over time, and some of the changes in status reflect changes to the classification of species. [10]

To be classified as threatened with extinction, a species is assessed against a set of five quantitative criteria. These criteria are based on biological factors related to extinction risk and include its rate of decline, population size, area of geographic distribution, and the degree to which its population has been fragmented.

Which species are threatened?

According to the IUCN, for most taxonomic groups only a small or extremely small proportion of described species has been evaluated for threatened status (for example, less than 0.1 per cent of insects). At present, birds and amphibians are the only organisms that have been completely evaluated. Mammals are almost all evaluated (99 per cent), but this figure is decreasing because a large number of changes in mammalian taxonomy have resulted in an increasing number of recognised species. Among plants,gymnosperms (mainly conifers and cycads) are the only major plant group to be almost completely evaluated (93 per cent).

Rate of extinctions in recent years
Number of described species Number of species evaluated by 2010 Number of threatened species in 1996&ndash98 Number of threatened species in 2007 Number of threatened species in 2008 Number of threatened species in 2009 Number of threatened species in 2010 Number threatened in 2010, as percentage of species described
Mammals 5,490 5,490 1,096 1,094 1,141 1,142 1,143 21%
Birds 9,998 9,998 1,107 1,217 1,222 1,223 1,223 12%
Reptiles 9,084 1,672 253 422 423 469 467 5%
Amphibians 6,433 6,284 124 1,808 1,905 1,895 1,895 29%
Fishes 31,300 4,446 734 1,201 1,275 1,414 1,414 5%
Subtotal 62,305 27,890 3,314 5,742 5,966 6,143 6,142 10%
Insects 1,000,000 2,886 537 623 626 711 740 0.06%
Molluscs 850,000 2,305 920 978 978 1,036 1,037 1%
Crustaceans 47,000 1,735 407 460 606 606 606 1%
Others 173,250 955 27 48 286 286 286 30%
Subtotal 1,305,250 7,881 1,891 1,928 1,932 1,959 1,992 34%
Source: 2009 Red List of Threatened Species ( Ref 9 )

Which ecosystems are under threat?

The Living Planet Report 2008, published by the WWF, is an indicator of the state of the world's ecosystems. The report tracks population trends for more than 1,600 freshwater, marine and terrestrial species. Between 1970 and 2005, populations of terrestrial species dropped by 33 per cent. Populations of marine species dropped by 14 per cent, and freshwater species by 35 per cent. [14]

Within each of these categories, some ecosystems are more threatened than others.

Today, just one-fifth of the world's original forest cover remains in large tracts of relatively undisturbed forest &mdash what the World Resources Institute calls 'frontier forest'. [15]

An estimated 58 per cent of the world's coral reefs, some of which rival tropical rainforests for biodiversity, are at risk from human activities. In South-East Asia, more than 80 per cent of reefs are at risk. [15]

How is agriculture affecting biodiversity?

Agriculture is a major contributor to loss of biodiversity. The rate at which agricultural land is expanding varies from region to region. However, much of the biodiversity loss due to agriculture is occurring in Latin America, Sub-Saharan Africa, and South and South-East Asia.

Area of agricultural land by region (1900&ndash1980) in sq km
1961 2007 % change
North America 5,175,730 4,789,970 +7.5
South America 4,409,030 5,801,850 +31.6
Europe 7,829,225 4,742,735 -39.4
World 44,571,055 49,318,620 +10.7
Eastern Africa 2,839,540 3,025,553 +6.6
South Asia 3,088,590 3,101,290 +0.4
South-East Asia 842,210 1,176,602 +39.7
China 3,432,480 5,528,320 +61
Source: International Institute for Environment and Development/World Resources Institute ( Ref 15)

What is the value of biodiversity?

The importance of biodiversity to the functioning of ecosystems is well established. There is also, however, a considerable body of research on the economic value of biodiversity.

If one species becomes extinct, this can have a knock-on effect on others it interacts with. Indeed, an analysis published in September 2004 in the journal Science [17] suggested that the number of species globally threatened with extinction is nearly 50 per cent higher than the number currently listed as endangered. This is because the survival of 6,300 non-threatened species depends on the existence of threatened species.

Some species are &mdash by virtue of their interactions with others &mdash important to the continued existence of their ecosystems. These are known as 'keystone' species. The extinction of a keystone species is predicted to cause a cascade of further extinctions.

What is the economic value of biodiversity?

Individual species play a critical role in human food, medicine, biological pest control, materials (such as timber) and, recently, recreation. Southern Africa's wildlife, for instance, attracted more than 9 million visitors in 1997, bringing a total of US$4.1 billion to the region.

Plant species used as food by humans
Human use/classification Plant species
Total described species 250,000
Edible 30,000
Cultivated 7,000
Important on national scale 120
Making up 90% of world's calories 30
Source: UN Food and Agriculture Organization ( Ref 18 )

Ten of the world's 25 top-selling drugs in 1997 were derived from natural sources. The global market value of pharmaceuticals derived from genetic resources is estimated at US$75 billion to US$150 billion annually. Some 80 per cent of the world's population relies for healthcare on traditional medicines, which are derived directly from natural sources. [3]

In China, for example, more than 5,000 of the estimated 30,000 identified domestic species of plants are used for medicinal purposes. More than 40 per cent of all prescriptions written in the United States contain one or more drugs that originated from wild species of fungi, bacteria, plants and animals. [18]

In addition to the importance of individual species, researchers are discovering that ecosystems, too, play an important role in providing 'services' to humans, and that these services can be given a monetary value.

In 2004, research published in the Proceedings of the National Academy of Sciences, for example, showed that conserving tropical forests could increase profits for coffee farmers in Costa Rica. [19] The study showed that the closer coffee bushes are planted to patches of forest, the more and better quality beans they produce, thanks to greater pollination by wild bees. Extra pollination provided by bees in these forest patches increased a Costa Rican coffee farm's income by 7 per cent.

Another study reveals direct and indirect financial benefits to humans from urban wetlands in Laos's That Luang Marsh. [20] At 20 km 2 , this is the largest wetland in the city of Vientiane, and generates goods and services with an economic value in excess of US$4.8 million per year. These benefits include water purification for people who live around the marsh, as well as for the residents of the city as a whole. [21]

Ecological economists study the relationship between economics and ecology. In 1997, a group of ecological economists tried to estimate a value for all of the world's 'ecosystem services'. Led by Robert Costanza of the University of Maryland in the United States, they calculated that the Earth provides 'services' worth a minimum of US$16 trillion to US$54 trillion to humans per year (compared to the global total gross national product (GNP) of US$18 trillion). [21] The study generated considerable controversy, not least from traditional economists who remain cautious about attempts to put monetary values on ecological services.

The 2006 Stern Review on the Economics of Climate Change warned that failing to act on climate change would cost the equivalent of between 5 and 20 per cent of GDP every year, with around 15 to 40 per cent of species potentially facing extinction after only 2 °C of warming. [22] A similar project is now underway to quantify the economics of biodiversity. It is called The Economics of Ecosystems and Biodiversity (TEEB) and is being coordinated by the UN Environment Programme.

How much of the planet is protected?

The 2003 United Nations List of Protected Areas [23] lists 102,102 sites covering 18.8 million km 2 . Of the total area protected, it is estimated that 17.1 million km 2 is in terrestrial protected areas, or 11.5 per cent of the global land surface. Marine areas are significantly under-represented in this global system of protected areas. Approximately 1.64 million km 2 is in marine protected areas &mdash an estimated 0.5 per cent of the world's oceans, and less than one-tenth of the overall extent of protected areas worldwide.

At least 300 critically endangered, 237 endangered and 267 vulnerable bird, mammal, turtle and amphibian species have no protection in any part of their ranges, according to the most comprehensive analysis of its kind, published in Nature in 2004. [24]

What is the cost of conserving biodiversity?

A network of marine protected areas covering 20 to 30 per cent of the world's oceans would cost between US$5 billion and US$19 billion annually to run, according to research published in Bioscience in 2004. [25]

Scientists estimate that between US$20 billion and US$25 billion must be spent annually to achieve effective global conservation. [26]

In 2002, five international organisations between them spent US$1.5 billion on conserving biodiversity. They are: the World Bank, the Global Environment Facility, the IUCN, The Nature Conservancy and the Wildlife Conservation Society. Half this amount was spent in the United States, according to new research from a team of US university researchers and global conservation organisations. [26]

Biodiversity-related aid has been falling, according to an analysis from the Development Assistance Committee (DAC) of the Organization for Economic Co-operation and Development (OECD). In 1998, DAC's 19 members spent almost US$1.1 billion on biodiversity-related projects. This fell to a little over US$1 billion the following year, and dropped again to US$865 million in 2000. [26]

The Global Environment Facility is the main funding mechanism for the UN Convention on Biological Diversity. Donors pledged US$1.8 billion to the fund in 2002. Nearly 17 per cent of this assistance is to be spent on biodiversity-related projects. [27]

The 2010 target and beyond

At the 2002 World Summit on Sustainable Development, the international community pledged to slow down the rate of global biodiversity loss by 2010. Indicators towards this target included effectively conserving at least 10 per cent of the world's ecological regions improving the status of threatened species ensuring that no species of wild flora or fauna is endangered by international trade and providing new and additional financial resources and technology to developing countries to help them meet their conservation commitments.

However, the target has not been met. The UN has declared 2010 the International Year of Biodiversity and member states of the UN Convention on Biological Diversity plan to meet to discuss future targets. The year will culminate in the Nagoya biodiversity summit in October, where they will set out a vision for 2050 and identify new targets and produce a new strategy to prevent biodiversity loss.

Laura Hood writes on global biodiversity policy for Research Europe (

This document updates an earlier version produced by Mike Shanahan and Ehsan Masood in October 2004.

Watch the video: Βιοποικιλότητα και ανθρώπινη δραστηριότητα (August 2022).