Chapter One - Biodiversity History PDF

Chapter one What is biodiversity? What is biodiversity ? Few people are familiar with the word “biodiversity,” yet everyone is intimately connected with biodiversity in their daily life. Humanity’s fundamental reliance on and connection with natural systems creates an imperative to unders...

Chapter one What is biodiversity? What is biodiversity ? Few people are familiar with the word “biodiversity,” yet everyone is intimately connected with biodiversity in their daily life. Humanity’s fundamental reliance on and connection with natural systems creates an imperative to understand and protect biodiversity. To conserve biodiversity, we need to understand : 1. what biodiversity is, 2. determine where it occurs, 3. identify strategies to conserve it, and 4. track over time whether these strategies are working. 2 10/11/2024 Chapter one LHA 2019 INTRODUCTION Life on earth today is the product of about 3.5 billion years of evolution. An estimated 1.75 million species have been discovered and described, but this only represents a fraction of all the species on earth. Species remain to be discovered range from 3.6 million to 117.7 million, with 13 to 20 million being the most frequently agreed upon by scientists. 3 10/11/2024 Add a footer  https://earthathome.org/geologic-time-scale/ 5 10/11/2024 Add a footer Table 1. This table shows the estimated number of species by taxonomic group—including both described (named and studied) and predicted (yet to be named) species. Estimated Numbers of Described and Predicted species Source: Groombridge and Jenkins Source: Mora et al 2011 Source: Chapman 2009 2002 Described Predicted Described Predicted Described Predicted Animals 1,124,516 9,920,000 1,424,153 6,836,330 1,225,500 10,820,000 Photosynthetic 17,892 34,900 25,044 200,500 — — protists Fungi 44,368 616,320 98,998 1,500,000 72,000 1,500,000 Plants 224,244 314,600 310,129 390,800 270,000 320,000 Non- photosynthetic 16,236 72,800 28,871 1,000,000 80,000 600,000 protists Prokaryotes — — 10,307 1,000,000 10,175 — Total 1,438,769 10,960,000 1,897,502 10,897,630 1,657,675 13,240,000  The exact number of species is still unclear because new species are continually being described. Some of this uncertainty is also due to the increased information available to scientists since the advent of genetic analyses and because the definition of what constitutes an individual species changes. 7 10/11/2024 Add a footer Content of the chapter This chapter introduces the basics of biodiversity: 1. what biodiversity is 2. how to measure it. 3. It also explores the evolution of biodiversity over time: a. how many species there are today, b. how many have disappeared, c. the “Sixth” extinction—the current rapid loss of biodiversity around the world 8 10/11/2024 Add a footer Definition of biodiversity Scientists first coined the term biodiversity, a contraction of the phrase, “biological diversity,” in the 1980s The origins of this term are credited to two papers published in 1980 by : 1.Lovejoy 1980 2.Norse and McManus 1980 9 10/11/2024 Add a footer Continue Definition of biodiversity However It can also be defined more broadly incorporating not only living organisms, but also their complex interactions with one another and with the nonliving aspects of their environment 1. The variety of life on Earth at all its levels, from genes to ecosystems, and the ecological and evolutionary processes that sustain it. 2. Biological diversity* means the variability among living organisms from all sources including, inter alia, 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. *(UN Conference on Environment and Development, Rio de Janeiro, 1992, Convention on Biological Diversity, Article 2) 10 10/11/2024 Add a footer  The Biodiversity Hierarchy To understand and appreciate the full variety of life encapsulated by the term “biodiversity,” scientists describe it based on a nested hierarchy, beginning at the subcellular scale and ending at the continental level (see Figure 1.1 in chapter one). The smallest level of this hierarchy refers to the diversity of genes that can be found in individual cells 11 10/11/2024 Add a footer  https://nbs.net/a-simple-and-visual-definition-of-biodiversity/ 12 10/11/2024 Add a footer  Genetic diversity is sometimes called the “fundamental currency of diversity,” as ultimately it is responsible for the variation among individuals, populations, and species. The next level of the hierarchy is the species level: this is the level of the biodiversity hierarchy that most conservation legislation targets, where most conservation organizations focus their efforts, and what most people think of when they think of biodiversity. 13 10/11/2024 Add a footer  The interactions between the individual organisms that make up a population (competition, cooperation, etc.), and their specializations for their environment (including ways in which they might modify the environment itself). Interactions between different species (e.g., predator-prey relationships) and their environments form the next level of the hierarchy, focusing on community and ecosystem biodiversity. The largest scales of the biodiversity hierarchy are landscapes and ecoregions. 14 10/11/2024 Add a footer  Genetic Diversity Is, the variation in the DNA (deoxyribonucleic acid) that makes up the genes of organisms leads to the variation we see at all other levels. It is also refers to any variation in the nucleotides, genes, chromosomes, or whole genomes of organisms (the genome is the entire complement of DNA within the cells or organelles of the organism). 15 10/11/2024 Add a footer  Genetic diversity, at its most elementary level, is represented by differences in the sequences of four nucleotides (adenine, cytosine, guanine, and thymine), which form the DNA within the chromosomes in the cells of organisms. Nucleotide variation is measured for discrete sections of chromosomes, called “genes.” Each gene comprises a hereditary section of DNA that occupies a specific place on the chromosome, and controls a particular characteristic of an organism. DNA provides the instructions to create proteins and in turn all other parts of a cell 16 10/11/2024 Add a footer  https://www2.nau.edu/lrm22/lessons/dna_notes/dna_notes.html 17 10/11/2024 Add a footer  https://www.gu.se/en/cemeb-marine-evolutionary-biology/management-conservation/baltgene/this-is-genetic-biodiversity 18 10/11/2024 Add a footer  Genetic diversity exists: within a single individual, between different individuals of a single population, between different populations of a single species (population diversity), and between different species (species diversity). 19 10/11/2024 Add a footer  Differences in the nucleotide sequences of alleles result in the production of slightly different proteins. These proteins lead to the development of traits or the specific anatomical and physiological characteristics that make up a particular organism. Variation between the alleles for each gene can be introduced through mutation, sexual reproduction, or through gene flow (as organisms move between different areas). 20 10/11/2024 Add a footer 1- Genetic Diversity 21 10/11/2024 Add a footer  Mutations are structural changes in an organism’s genes that can be passed on to the next generation. For species that reproduce sexually (when reproduction requires two individuals), the offspring inherit one allele from each parent, whose alleles may be slightly different. This difference in alleles is more likely if parents come from different populations and gene pools. Also, when the offspring’s chromosomes are copied after fertilization, genes can be exchanged in a process called sexual recombination, adding additional variation. Harmless mutations and sexual recombination may allow the evolution of new characteristics. 22 10/11/2024 Add a footer  Mutation can occur randomly during DNA replication https://my.clevelandclinic.org/health/body/23095-genetic-mutations-in-humans 23 10/11/2024 Add a footer Genetic Studies Examination of these chromosomal features is another way of describing genetic diversity. Besides having distinct combinations of genes, species may also vary the total number of chromosomes present, as well as the shape and composition of the chromosomes. Different species vary in the number of genes or chromosomes within their DNA or genome. 24 10/11/2024 Add a footer  Analyses of genetic diversity can be applied to studies of the evolutionary ecology of populations. Genetic studies can identify alleles that might affect the ability of an organism to survive in its existing habitat, or might enable it to survive in more diverse habitats. Inherited characteristics form the basis for “natural selection”—some alleles or genes confer a selective advantage on an organism, making it more likely to survive than if it did not have them. The presence of unique genetic characteristics distinguishes members of a given population from those of other populations. Large populations usually have a greater diversity of alleles than small ones. 25 10/11/2024 Add a footer  This diversity of alleles indicates a greater potential for the evolution of new combinations of genes and, subsequently, a greater capacity for evolutionary adaptation to different environmental conditions. In small populations, individuals are likely to be genetically, anatomically, and physiologically more alike than in larger ones and thus less adaptable to changing environmental conditions and more susceptible to disease. This situation of low genetic diversity is sometimes known as the “inbreeding effect. 26 10/11/2024 Add a footer  https://www.solpass.org/science6-8-new/s7/standards7/ls11-2018.html?section=study-6 27 10/11/2024 Add a footer  Maintaining genetic diversity is a key component of conservation efforts. Cheetahs (Acionyz jubatus) and the northern Elephant Seal (Mirounga angustirostris) are famous for having populations with low genetic diversity. The low genetic diversity is a concern for many endangered species from the Mediterranean monk seal (Monachus monachus) to the Northern hairy-nosed wombat (Lasiorhinus krefftii). 28 10/11/2024 Add a footer  Phenotypic Diversity Genes code for what something looks like or the outward expression of physical traits of an organism however, the environment also modifies the way genes are physically expressed in the organism. The physical appearance of an organism results from its genetic makeup or genotype, and the action of the environment on the expression of the genes is termed its phenotype. Phenotypic variation, refers to the variation of the physical traits, or phenotypic characters of the organism, such as differences in anatomical, physiological, biochemical, or behavioral characteristics. 29 10/11/2024 Add a footer 30 10/11/2024 Add a footer  Phenotypic diversity is a product of genetic diversity and the influence of the environment on gene expression. Local environmental conditions can alter phenotypic characters. For example in plants, leaf shape varies significantly among individuals of the same species occupying different habitats (e.g., dry versus wet sites, or sunny versus shaded sites). In a classic study of human twins separated at birth, the twin who was raised in a high altitude environment had a bigger heart and lungs than the one raised at sea level. 31 10/11/2024 Add a footer 32 10/11/2024 Add a footer  The extent to which genetic variation between organisms is expressed in their phenotypes can be quite variable for different characteristics. Genetic variation between some features might be expressed as very subtle differences in their phenotype. Example: populations and subspecies of the herring gull (Larus argentatus) and the lesser blackbacked gull (Larus fuscus) are distinguished by very slight differences in the coloration of individuals Lesser herring gull blackbacked gull 33 10/11/2024 Add a footer  Or in some cases these differences are difficult to detect. However, genetic variation within a species can be quite extensive, particularly in cultured plants or domesticated animals where particular features have been artificially selected in different strains or breeds. For example, broccoli, cabbage, and cauliflower look very different from one another, but are all varieties of Brassica oleracea https://medium.com/@Lavandula/ode-to-brassica-oleracea-8e0c909b4b5e 34 10/11/2024 Add a footer  Population Diversity A population is a group of the same species with a shared characteristic, usually living in the same area. Scientists also differentiate populations by their breeding rates and migration patterns, among other characteristics. The simple way to measure its diversity is to simply determine the area that a population occupies. Using this criterion, a population is a group of individuals of the same species occupying a particular area at the same time. The area occupied is usually defined based on ecological needs important to the species: for example, a particular pond or lake for a population of fish, or a south-facing slope for a population of light- loving trees. 35 10/11/2024 Add a footer  Population Diversity 36 10/11/2024 Add a footer  The geographic range and distribution of populations represent key factors in analyzing population diversity because they give an indication of the likelihood of movement of individuals between populations, and consequently of genetic and demographic interchange. Where the population size provides a measure of the potential genetic diversity within the population; large populations usually represent larger gene pools and hence greater potential diversity 37 10/11/2024 Add a footer  Isolated populations, with very low levels of interchange, may show high levels of genetic divergence, and exhibit unique adaptations to the biotic and abiotic characteristics of their habitat. The genetic diversity of groups that generally do not disperse well—such as amphibians and some herbaceous plants—may be restricted to local populations. For this reason, range retractions of species leads to loss of local populations and the genetic diversity they hold. Loss of isolated populations, along with their unique genetic variation, is considered by some scientists to be one of the greatest but most overlooked tragedies of the biodiversity crisis. 38 10/11/2024 Add a footer  Isolated populations of species are basically incubators for new species; when they disappear, the potential for the evolution of a new species also disappears. Populations can be categorized according to the level of divergence between them. Isolated and genetically distinct populations of a single species are often called subspecies. 39 10/11/2024 Add a footer  Luque et al., 2016 40 10/11/2024 Add a footer  Species Diversity Most of the environmental management and political attention focuses on individual species. Species diversity has two components: the number of different species in a particular area (species richness). and the relative abundance of individuals within different species in the same area that known as species evenness. An ecosystem in which all the species are represented by the same number of individuals has high species evenness. In contrast, an ecosystem in which some species are represented by many individuals, and other species are represented by very few individuals, has low species evenness 41 10/11/2024 Add a footer  Species diversity encompasses both species richness and evenness. It is common, though incorrect, for people to use the term “species diversity” interchangeably with species richness. For example a mixed-hardwood forest in the northeastern United States is dominated by beech and maple trees, with birch and ash trees at lower densities. These forests have high species evenness, but low overall species richness. In contrast, tropical rainforests have hundreds of species per acre, but each one at a low abundance. Thus, they have high species richness but low species evenness. 42 10/11/2024 Add a footer Which one do you think that has the higher biodiversity? Why?  Scientists and conservation managers use diversity indices to quantitatively describe species diversity. Examples of the most well- known diversity indices are the Shannon index and Simpson’s diversity index (D), which incorporate both species richness and species evenness within an area. Ashram, 2017 44 10/11/2024 Add a footer  What Is a Species? To count the number of species, we must define what we mean by a species. They are three common concepts used for defining species which are : 1. The morphological, 2. biological, 3. and phylogenetic The concepts center on ideas of genetic relatedness, or ancestry, among species. 45 10/11/2024 Add a footer  Morphological Species Concept The morphological species concept is the oldest of the approaches currently used to answer the question, what is a species, and also the most readily understandable. According to this concept, individuals that look alike and share the same identifying traits belong to the same species. While this is an outdated concept, this is still the method that biologists initially use to distinguish one species from another in a field setting One flaw of this concept is that it is really a matter of opinion as to how similar two individuals must be in order to count them as the same species. 46 10/11/2024 Add a footer  This method is a useful way to generally categorize species, but its application is limited at finer levels. Genetic analyses are leading to a reevaluation of the concept as discoveries reveal that individual animals that superficially look the same are actually different species. According to the scientific method, scientific conclusions should be based on reproducible and verifiable data, which can be arrived at no matter who follows the method. 47 10/11/2024 Add a footer  The morphological species concept relies too heavily on accumulated experience rather than deductive methods for distinguishing between species and thus it is too subjective, so scientists have searched for other ways to describe species. 48 10/11/2024 Add a footer Biological Species Concept The biological species concept, defines species as a group that interbreeds and is isolated from other groups. Basically, two individuals are the same species if they can breed and produce viable offspring—that is offspring that can also breed. This approach is an improvement on the morphological species concept because it uses a testable characteristic to differentiate between species. Problems with this approach to defining a species is that it is difficult to apply to organisms that do not reproduce sexually or to organisms that do not normally live in the same place or time, so it is impossible to know whether they would interbreed. 49 10/11/2024 Add a footer  Phylogenetic Species Concept The phylogenetic species concept defines the species as a group of individual organisms that share a common ancestor (focus on evolutionary relationships among organisms) A species is defined as a cluster of organisms that is distinct from other clusters and shows a pattern of relationship among organism. This approach is more complex to apply than the morphological approach, and recognizes more species than the biological species concept. https://www.britannica.com/story/how-do-you-read-phylogenetic-trees 50 10/11/2024 Add a footer  All species concepts are based on the understanding that there are parameters that make a species a discrete and identifiable evolutionary entity. If populations of a species become isolated, either through differences in their distribution (i.e., geographic isolation) or through differences in their reproductive biology (i.e., reproductive isolation), they can diverge, ultimately resulting in the creation of new species. Some researchers describe these as subspecies, or some other subcategory, according to the species concept used. 51 10/11/2024 Add a footer  For these reasons, deciding if a population merits subspecific and infra-subspecific ranks may become extremely subjective decisions. This becomes particularly important for conservation decisions. For example are we concerned when a small population, such as the Florida panther, disappears, if we know there are other panther populations still present elsewhere? If we consider a Florida panther to be distinct enough then it does matter. Depending on which species concept is used, there are different conservation priorities. Some species concepts will recognize Florida panthers as a distinct subspecies and thus a high conservation priority, other species concepts will consider them too similar to panthers elsewhere and thus Florida panthers are a lower conservation priority. 52 10/11/2024 Add a footer How Many Species Are There? Although species diversity has generally risen over time, the majority of species that have ever lived are now extinct. Estimates put the current animal and plant species diversity at 2- 5 % of the historic total. (from fossil records) Estimates of the total number of species in the world are based on extrapolations from what we already know about certain groups of species. A recent estimate suggests that only 13% of eukaryotic species have been named (Table 1). Estimates of numbers of prokaryotic species are largely guesses, but biologists agree that science has only just begun to catalog their diversity. Given that Earth is losing species at an accelerating pace, science knows little about what is being lost. 53 10/11/2024 Add a footer  Birds and mammals are very well documented, though there are some surprises, e.g. the Udzungwa partridge (Xenoperdix udzungwensis) a bird species first identifies in 1991. Numbers of many invertebrates and microorganisms remain not certain. Estimates of global diversity have changed throughout history. As taxonomists develop more techniques to uncover genetic and phenotypic diversity, they provide more reliable estimates of the number of species on the planet. *provided as hard copy in the class Source: http://adtrack.ministerial5.com/clicknew/?a=637394  Ecosystem Diversity An ecosystem is a community plus the physical environment that it occupies at a given time. An ecosystem can exist at any scale, for example, from the size of a small tide pool up to the size of the entire biosphere. Ecosystems may be classified according to the dominant type of environment, or the dominant type of species present; for example, a salt marsh ecosystem, a rocky shore intertidal ecosystem, a mangrove swamp ecosystem. 55 10/11/2024 Add a footer  The diversity of an ecosystem depends on the physical characteristics of the environment, the diversity of species present, and the interactions that the species have with each other and with the environment. Souna, 2021 56 10/11/2024 Add a footer  The physical characteristics of an environment that affect ecosystem diversity are themselves quite complex. These include, the temperature, precipitation, and topography of the ecosystem. There is a general trend for warm and moist tropical ecosystems to be richer in species than cold temperate ecosystems. The organisms in turn also modify the physical characteristics of the ecosystem. For example, stony corals (Scleractinia) build extensive calcareous skeletons that are the basis for coral reef ecosystems that extend thousands of kilometers, as is the case for the Great Barrier Reef in Australia. 57 10/11/2024 Add a footer  Trees modify the microclimate as well as the structure and chemical composition of the soil around them. When pine needles decompose, for example, the soil becomes more acidic, which limits the plant species that can establish there. Environmental disturbance on a variety of temporal and spatial scales affects the species richness and, consequently, the diversity of an ecosystem. Occasional disturbance can have the reverse effect, and increase the species richness of an ecosystem by creating spatial heterogeneity in the ecosystem, allowing new species to colonize or by preventing certain species from dominating the ecosystem. 58 10/11/2024 Add a footer  Landscape Diversity A landscape is made up of a collection of common land forms, vegetation types, and land uses. Therefore, assemblages of different ecosystems (the physical environments and the species that inhabit them, including humans) create landscapes on Earth. Although there is no standard definition of the size of a landscape, they are usually on the order of hundreds or thousands of square kilometers (tens or hundreds of square miles, or tens to hundreds of thousand acres). 59 10/11/2024 Add a footer  The landscape level of biodiversity is a relatively new horizon for scientific research due to technological innovations in analyzing satellite images and geographic information systems (GIS) software. The study of landscapes is often closely tied to land use planning and human use of land. Species composition and population viability are often affected by the structure of the landscape; for example, the size, shape, and connectivity of individual patches of ecosystems within the landscape. Diversity within and between landscapes depends on local and regional variations in environmental conditions, as well as the species supported by those environments. Landscape diversity is often incorporated into descriptions of “ecoregions” 60 10/11/2024 Add a footer Ecoregions Ecoregions include ecosystems that share certain distinct characters. An ecoregion is a large area of land or water (typically spanning millions of acres or thousands of square kilometers) with a geographically distinct collection of species and natural communities. Several standard methods of classifying ecoregions have been developed, with landform, climate, altitude, ecological processes, and predominant vegetation being as important criteria for classification. 61 10/11/2024 Add a footer 62 10/11/2024 Add a footer  https://www.larkswood.co.uk/world-biomes-map 63 10/11/2024 Add a footer biodiversity history biodiversity over time Biodiversity over Time The evolutionary history of Earth has physically and biologically shaped our contemporary environment. Plate tectonics and the evolution of continents and ocean basins have been instrumental in directing the evolution and distribution of the Earth’s biota. The physical environment has also been extensively modified by these biota. Many existing landscapes are based on the remains of earlier life forms. 65 10/11/2024 Add a footer  For example, some existing large rock formations are the remains of ancient reefs formed 360 to 440 million years ago by communities of algae and invertebrates. 66 10/11/2024 Add a footer  Extinction Extinction, or the complete disappearance of a species from Earth, is an important part of the evolution of life. The current diversity of species is a product of the processes of extinction and speciation throughout the 3.5 billion year history of life. Assuming there are about 40 million species alive today, and between 5 and 50 billion species have lived at some time during the history of the Earth, then 99.9 % of all the life that has existed on Earth is now extinct (Raup 1991). Most (if not all) species eventually become extinct. The average duration of a species in the fossil record is a few million years. Most vertebrates last about 1 to 3 million years, while invertebrates last about 10 to 30 million years. 67 10/11/2024 Add a footer  There are some species that have the ability to survive unchanged over long periods of time. The horseshoe crab is an example for these ancient species. Recent fossils discovered in Manitoba in 2007 indicate it originated 450 million years ago. It is the oldest marine arthropod, actually more closely related to spiders than crabs. It is still widespread; besides the species in the Atlantic Ocean, three species in the same family (Limulidae) are found in the Indian and Pacific Oceans, it is particularly common in the Gulf of Mexico. 68 10/11/2024 Add a footer  Extinction has not occurred at a constant pace through the Earth’s history. There have been at least five mass extinctions, periods when the extinction has more than doubled, and the taxa affected have included representatives from many different taxonomic groups of plants and animals. They occurred at the end of the Ordovician, Devonian, Permian, Triassic, and Cretaceous periods (see Table 1.6 in the ebook). The most famous of these was at the end of the Cretaceous when the dinosaurs disappeared, as did two-thirds of marine life. 69 10/11/2024 Add a footer Mass extinction The analysis provide stark estimation of species loss. 1. Late Ordovician 84-85 % (two major events : glaciation and falling sea levels). 2.Late Devonian 79-83% (Giant land plants deep roots released nutrients into the oceans resulted in mass amounts of algal blooms which depleted the seas of oxygen) 3.End Permian 95%(volcanic eruption -air with carbon dioxide produce bacteria that emitting methane). 4.End Triassic 79-80% (asteroid, climate change, and flood basalt eruptions) 5.K/T (Cretaceous-Tertiary) event 70-76% (volcanic activity, asteroid impact, and climate change) Natural extinctions: type of extinction https://ourworldindata.org/mass-extinctions  Each of the first five mass extinctions represents a significant loss of biodiversity—but species diversity recovered over geologic time scales. Mass extinctions are apparently followed by a sudden burst of evolutionary diversification on the part of the remaining species; some evolutionary biologists suggest this is because the surviving species start using habitats and resources that were previously “occupied” by species that went extinct. However, these bursts of diversification do not mean that the recoveries from mass extinction have been rapid; they have usually required some tens of millions of years. 72 10/11/2024 Add a footer  Many scientists believe we are on the brink of a “sixth mass extinction,” but one that differs from previous events. The five other mass extinction predated humans, and while theories abound about their causes, they were probably due to some physical process (e.g., catastrophic climate change through meteor impacts or volcanic eruptions), rather than the direct consequence of the action of some other species. In contrast, the sixth mass extinction is the product of human activity over the last several hundred, or even thousand years. 73 10/11/2024 Add a footer  The extinction of the passenger pigeon (Ectopistes migratorius) in the United States is a dramatic example of human-caused extinction. At the time of the European settlement of North America, passenger pigeons represented 25 to 40 percent of the total bird population of North America. Populations are estimated to have been as high as 3 to 5 billion birds; recent studies suggest that the high population may have also been due to the loss of their predators. Widespread forest clearing and then large-scale hunting of the birds for urban markets eventually led to the passenger pigeon’s precipitous decline at the end of the nineteenth century. Once governments and citizens recognized the problem and attempted to address it, however, it was too late. The passenger pigeon required large flocks to breed successfully The extinction of the passenger pigeon (Ectopistes migratorius) in and could not adapt to survive within smaller flocks. The last the United States is a dramatic example known passenger pigeon died in captivity in 1914 of human-caused extinction 74 10/11/2024 Add a footer Extinct A taxon is EXTINCT when there is no reasonable doubt that its last individual has died and they are gone forever. There are no more of that kind of animal species anywhere in the world. Extinct in the wild –when it is known only to survive in cultivation, in captivity or as a naturalized population (or populations) well outside the past range Examples of Extinct Species Image from https://storify.com/Opatton09/research-academic-article-summary Critically endangered (CR) A taxon is critically endangered when it is facing extremely high risk of extinction in the wild in the immediate future as defined in any of the criteria. Examples of Critically Endangered Species Ethiopian wolf Canis simensis Diceros bicornis (Black Rhino) Gorilla Gorilla beringei Endangered (EN) A taxon is endangered when it is not critical but facing a very high risk of extinction in the wild in the near future, as defined in any of the criteria BlueFin Tuna  Lynx pardinus gray wolves 82 10/11/2024 Add a footer  Vulnerable (VU) A taxon is vulnerable when it is not critical or endangered but is facing a high risk of extinction in the wild in the medium–term future as defined in any of the criteria. Mountain Zebra March Deer African Elephant Giant Panda Polar Bear  Low Risk – A taxon is low risk when it has been evaluated and does not qualify for any of the categories: Critical, endangered, vulnerable, conservation dependent or data deficient. Conservation dependent –a taxon must be the focus of a continuing taxon specific or habitat specific conservation program which directly affects the taxon in question. Data Dependent – A taxon is data deficient when there is inadequate information to make a direct or indirect assessment of its risk or extinction based on its distribution and / or population status. Not Evaluated – A taxon is not evaluated when it has not yet been assessed `to against the criteria  References Ashram, S., Nasr, I., Rashid, Hu, M., (2017). Next Generation Sequencing And Microbial Community Associated With Eukaryotes Including Parasitic Heliminths: A Review Article. International Journal of Advanced Research, 5(3), 1003–1022. https://doi.org/10.21474/IJAR01/3599 Laverty, Melina F., et al. Biodiversity 101, ABC-CLIO, LLC, 2008. Luque, G. M., Vayssade, C., Facon, B., Guillemaud, T., Courchamp, F., & Fauvergue, X. (2016). The genetic Allee effect: A unified framework for the genetics and demography of small populations. Ecosphere, 7(7), e01413. https://doi.org/10.1002/ecs2.1413 Souna, F. (2021). Contributions to population dynamics models. https://doi.org/10.13140/RG.2.2.13311.53928 86 10/11/2024 Add a footer