EXTINCTION PROCESSES EXTINCTION PROCESSES

v Rare species are at risk due to: – environmental stochasticity

Environmental Stochasiticity Examples – variable rate of increase Muskox population on Nunivak Island, (Akcakaya et al. 1999)

Environmental Stochasiticity - Example of random K v Serengeti wildebeest data set – recovering from Rinderpest outbreak –Fluctuations around K possibly related to rainfall

EXTINCTION PROCESSES EXTINCTION PROCESSES v Rare species are at risk due to: – demographic stochasticity

EXTINCTION PROCESSES EXTINCTION PROCESSES v Rare species are at risk due to: – genetic stochasticity

EXTINCTION PROCESSES EXTINCTION PROCESSES A. Specialization – habitat restriction u proboscis monkeys and mangrove swamps

EXTINCTION PROCESSES EXTINCTION PROCESSES A. Specialization – habitat restriction – range restriction u golden-lion tamarins

EXTINCTION PROCESSES EXTINCTION PROCESSES A. Specialization – habitat restriction – range restriction – body size and home-range size u maned wolf Photo by Pete Oxford

EXTINCTION PROCESSES EXTINCTION PROCESSES A. Specialization B. Catastrophes – earthquakes, asteroids – 5 mass extinctions – Cretaceous-Tertiary extinctions

EXTINCTION PROCESSES EXTINCTION PROCESSES A. Specialization B. Catastrophes – the human catastrophe – humans have caused 75% of extinctions since 1600

HUMANS AND EXTINCTION HUMANS AND EXTINCTION A. Role of Overexploitation – Lessons from North America

HUMANS AND EXTINCTION A. Role of Overexploitation – Bison A. Role of Overexploitation – Bison presettlement: ca. 60 million presettlement: ca. 60 million used food, hides used food, hides weapon against Native Americans weapon against Native Americans by 1889: only 600 by 1889: only 600

HUMANS AND EXTINCTION HUMANS AND EXTINCTION A. Role of Overexploitation B. Role of Exotics – introduced organisms – cause of 20% of extinctions since 1600

HUMANS AND EXTINCTION HUMANS AND EXTINCTION B. Role of Exotics – Feral Pigs u game species u destroy understory and groundcover u effect on brown honeycreeper u expensive to exterminate Po’ouli, n = 3 on 2/03

HUMANS AND EXTINCTION HUMANS AND EXTINCTION B. Role of Exotics – Domestic Cats u domesticated to kill pests u in 1/3 of U.S. households u humans support high densities

HUMANS AND EXTINCTION HUMANS AND EXTINCTION v Cats: Effects on Native Wildlife – Wisconsin: 19 million songbirds, 140,000 game birds per year – Great Britain: 50 million small mammals per year – Australia: endangerment of eastern barred bandicoot Photo: Ian McCann

HUMANS AND EXTINCTION HUMANS AND EXTINCTION C. Role of Human Population Size – most abundant mammal (Suzuki) – currently about 6.7 billion – stabilize at ~9 billion by 2042?

HUMANS AND EXTINCTION C. Role of Human Population Size – Habitat Destruction – Habitat Disturbance

CONSERVATION AND HUMAN RESOURCE USE

CONSERVATION AND HUMAN RESOURCE USE Richmond, VA – USDA photo

CONSERVATION AND HUMAN RESOURCE USE Texas oil wellsRussian coal power plant

CONCLUSION  Conservation will fail unless: – human population is controlled – human resource use is moderated

Reintroductions & Translocations

Wildlife Reintroductions v Does habitat remain?

Wildlife Reintroductions v Viable Population? –PVA u VORTEX u RAMAS

Wildlife Reintroductions v Viable Population? –PVA u VORTEX u RAMAS u Incorporate GIS

Wildlife Reintroductions v Genetic Considerations –

Genetic Considerations: Why Should You Care? v Genetic variation is the underlying basis for adaptation to future environmental change v Loss of genetic variation is often a direct consequence of species reintroduction v Understanding how genetic loss occurs can help to prevent management actions that decrease the genetic diversity of reintroduced wildlife species

Wildlife Reintroductions v Genetic Considerations –Inbreeding

Wildlife Reintroductions v Genetic Considerations –Founder Effect

Founder Effect v The reduction in overall genetic diversity experienced as a consequence of population establishment from a limited sample of individuals –Most reintroductions and natural colonization events exhibit Founder Effects –The magnitude of the effect depends upon the number of animals translocated or colonizing an area

Wildlife Reintroductions v Genetic Considerations –Genetic Bottleneck

Bottleneck v An event in which a population drops significantly in size and then recovers v Events such as habitat loss, over harvest, or reintroduction can create bottlenecks and the magnitude of the effect on genetic diversity depends upon: –Number of individuals at lowest point –Length of time population remains depressed

Genetic Drift v Random fluctuations in gene frequencies due to temporal variance in survival and reproduction –Small populations drift more rapidly than large ones –Higher reproductive and survival rates can slow the rate of genetic drift –Genetic drift can result in loss of genetic diversity as well as increases in the frequency of rare alleles

Inbreeding v Mating of closely related individuals v Anytime genes that are alike by descent (i.e., from a shared ancestor) come together within individuals –Enhanced by slow population growth rates –Affected by mating system –Influenced by the relatedness of the initial population founders (e.g. reintroductions)

Hypothetical Source Population Different Colors Represent Copies of Different Genes

Trap and Transplant Reintroduced Population

Founder Effects

Genetic Drift Inbreeding Generation Bottleneck

Genetic Drift Inbreeding Loss of Allelic Diversity Apparent 20 Generation Bottleneck 20

Genetic Drift Inbreeding 30 Generation Bottleneck 30

Wildlife Reintroductions v Genetic Considerations –Marten reintroductions