Extinction

The dodo What makes species vulnerable to extinction?

Passenger pigeon

Passenger pigeon

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

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

Konza Prairie – Kansas

African wild dog

California Condor

Coho salmon

Salmon Life Cycle

Coho Salmon support 137 species

Worldwide Endangered Species

Endangered tree species - worldwide

Rare and Endangered Species in Japan

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

Threatened and Endangered Species

Threatened And Endangered Species in Illinois

Four-toed salamander – found at Green Oaks

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

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

Environmental Fluctuations

Kirtland’s Warbler

Cheetah

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

Domesday Book –

Selection from the Domesday Book

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

Heath Hen – Extinction Vortex

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

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

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

Grizzly Bear and 50/500 Rule

MVP – 50/500 Rule?

English Skylark