BESC 201 10 28 2013 Lecture 24 Outline of Last Lecture I Genetically Modified Food Outline of Current Lecture II Chapter 8 Central Case Study III Our Planet of Life IV Extinction and Biodiversity Loss Current Lecture 10 28 2013 Biodiversity and Conservation Biology Central Case Study Saving the Siberian Tiger Just over 3 000 tigers survive down from 100 000 a century ago The tigers last refuge is in the forests of the remote Sikhote Alin Mountains of the Russian Far East Poachers hunt tigers for sport hides and body parts Logging road building and agriculture degraded and fragmented tiger habitat providing easy access for poachers The Hornocker Wildlife Institute now part of the Wildlife Conservation Society WCS launched the Siberian Tiger Project In November 2010 leaders of the 13 nations where tigers still survive met at a historic summit in St Petersburg Russia marking the first time that multiple heads of state had ever convened to focus on saving a single species of wild animal At this International Tiger Forum the leaders signed a declaration that set in motion a strategic multinational plan called the Global Tiger Recovery Program o Aims to double the tiger population by 2022 the nest Year of the Tiger by the Chinese zodiac Our Planet of Life Biodiversity encompasses multiple levels Biological Diversity describes the variety of life across all levels of biological organization including the diversity of species their genes their populations and their communities These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute The level that is easiest to visualize and most commonly used is species diversity Species Diversity Species a distinct type of organism a set of individuals that uniquely share certain characteristics and can breed with one another and produce fertile offspring Species Diversity the number or variety of species in a particular region Species Richness the number of species Evenness Relative Abundance the extent to which species differ in number of individuals Taxonomists classify species by their similarity into a hierarchy of categories meant to reflect evolutionary relationships Subspecies populations of a species that occur in separate geographic areas and differ in some characteristics Scientists denote subspecies with a third part of the scientific name Genetic Diversity encompasses the differences in DNA composition among individuals Scientists designate subspecies when they recognize substantial genetically based differences among individuals from different populations in a species Genetic diversity provides the raw material for adaptation to local conditions Populations with little genetic diversity are vulnerable to environmental change because they may happen to lack genetic variants that would help them adapt to novel conditions Inbreeding Depression genetically similar parents mate and produce weak or defective offspring Ecosystem Diversity refers to the number and variety of ecosystems Many species await discovery Knowledge of species numbers is incomplete for several reasons 1 Many species are tiny and overlooked 2 Many organisms are so difficult to identify that ones thought to be identical sometimes turn out to be multiple species 3 Some areas of Earth remain little explored Biodiversity is unevenly distributed Insects show a staggering predominance over all other forms of life Species richness generally increases as one nears the equator Relatively stable climates of equatorial regions discourage single species from dominating ecosystems and allows numerous species to coexist Variable environmental conditions favor generalists stable conditions favor specialists Ecotones support high biodiversity Extinction and Biodiversity Loss Extinction the last member of a species dies and the species ceases to exist Extirpation the disappearance of a particular population from a given area but not the entire species globally Extirpation is an erosive process that can lead to extinction Earth has experienced five mass extinction episodes Today s ongoing mass extinction is different in two respects First we are causing it Second we will suffer as a result We are setting the sixth mass extinction in motion Species loss is accelerating as our population growth and resource consumption put increasing strain on habitats and wildlife Red List an updated list of species facing high risks of extinction Biodiversity loss involves more than extinction Many species today are less numerous and occupy less areas that they once did Living Planet Index summarizes trends in the populations of 2 544 vertebrate species that are sufficiently monitored to provide reliable data Several major causes of biodiversity loss stand out Habitat Loss Habitat loss is the single greatest cause of biodiversity loss today Lost most rapidly in tropical rainforests tropical dry forests and savannas Most commonly through gradual piecemeal habitat fragmentation Pollution Overharvesting For most species hunting or harvesting by people will not in itself pose a threat of extinction but for K selected species it can Invasive Species Climate Change As our emissions of greenhouse gases from fossil fuel combustion cause temperatures to warm worldwide we modify weather patterns and increase the frequency of extreme weather events Warming temperatures force organisms to shift their geographic ranges toward the poles and higher in altitude Some species will not be able to adapt