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Extinction. The dodo What makes species vulnerable to extinction?

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Presentation on theme: "Extinction. The dodo What makes species vulnerable to extinction?"— Presentation transcript:

1 Extinction

2 The dodo What makes species vulnerable to extinction?

3

4 Passenger pigeon

5 Passenger pigeon

6 Allee Effect Some species have a minimum requirement for population size in order to successfully breed

7 Characteristics that predispose species to becoming extinct 1. habitat overlap - the species occupy habitat that is desirable to humans and lose out in competition with humans for the habitat - tallgrass prairie species 2. human attention - species suffer because singled out by humans - either desired as food or fur and hunted heavily (passenger pigeon, dodo, northern elephant seal); or disliked by humans and killed as varmints (wolves, African wild dogs) 3. large home range requirements - animals needing large areas can’t find large enough areas in human dominated landscape - California condor 4. limited adaptability and resilience - salmon return to natal stream to reproduce; won’t go elsewhere

8 Konza Prairie – Kansas

9 African wild dog

10 California Condor

11 Coho salmon

12 Salmon Life Cycle

13 Coho Salmon support 137 species

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16 Worldwide Endangered Species

17 Endangered tree species - worldwide

18 Rare and Endangered Species in Japan

19 Endangered species in Canada and the US – as of 1990’s

20 Threatened and Endangered Species

21 Threatened And Endangered Species in Illinois

22 Four-toed salamander – found at Green Oaks

23 Minimum Viable Population The smallest population for a species which can be expected to survive for a long time Many factors effect MVP – the study of those factors is often called Population Viability Analysis – or Population Vulnerability Analysis – or PVA

24 Factors that make populations vulnerable to extinction Environmental fluctuations Catastrophes Demographic uncertainties Genetic problems Habitat fragmentation

25 Environmental Fluctuations

26 Kirtland’s Warbler

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29 Cheetah

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31 Habitat Fragmentation Fragmentation is the transformation of large expanse of habitat into a number of smaller patches of smaller total area isolated from each other by a matrix of habitat unlike the original

32 Domesday Book – 1085-86

33 Selection from the Domesday Book

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35 Factors that make populations vulnerable to extinction Environmental fluctuations Catastrophes Demographic uncertainties Genetic problems Habitat fragmentation

36 Heath Hen – Extinction Vortex

37 Minimum Viable Population Size Another definition - often defined as 95% probability of 100 year survival, but can also plan for longer survival (500 or 1000 years) MVP is usually determined by modeling

38 Forces which may cause extinction 1) deterministic - something essential is removed (habitat loss) or something lethal is added (pollutant, disease, introduced species) - presumably we can act to minimize these risks

39 Forces which may cause extinction 2) stochastic (random) - environmental, catastrophic, demographic and genetic - this is what we need to worry about and what is hardest to prevent environmental randomness effects resources and conditions and we can't do much about it catastrophic randomness - floods, fires, hurricanes, volcanoes - can't really prevent but can spread individuals around to minimize the impact demographic - just natural random variation in birth and death rates can lead to extinction genetic - lack of genetic variability can lead to problems of inbreeding and poor response to diseases and environmental change

40 Grizzly Bear and 50/500 Rule

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42 MVP – 50/500 Rule?

43 English Skylark

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