extinction processes extinction processes v rare species are at risk

EXTINCTION EXTINCTION PROCESSES PROCESSES

Rare species are at riskRare species are at risk

EXTINCTION EXTINCTION PROCESSES PROCESSES

Rare species are at riskRare species are at risk

Time (years)

10 20 30 40 50 60Po

pu

lati

on

s P

ersi

stin

g (

%)

0

20

40

60

80

100

N < 16

N = 16-30

N = 31-50

N = 51-100

N > 100

Bighorn Sheep on Mountain Ranges

Source: Berger (1990, Cons. Biol. 4:91-98)

EXTINCTION EXTINCTION PROCESSES PROCESSES

Rare species are at risk due toRare species are at risk due to::– environmental stochasticityenvironmental stochasticity

Random variation in habitat qualityRandom variation in habitat quality Extreme cases = catastrophesExtreme cases = catastrophes

Environmental Environmental StochasiticityStochasiticity

Examples – variable Examples – variable rate of rate of increaseincrease

Muskox population on

Nunivak Island, 1947-1964

(Akcakaya et al. 1999)

Environmental Environmental StochasiticityStochasiticity- - Example of random KExample of random K

Serengeti wildebeest data set – recovering from Serengeti wildebeest data set – recovering from Rinderpest outbreakRinderpest outbreak– Fluctuations around K possibly related to rainfallFluctuations around K possibly related to rainfall

EXTINCTION EXTINCTION PROCESSES PROCESSES

Rare species are at risk due toRare species are at risk due to::– demographic stochasticitydemographic stochasticity

Random variation birth/death ratesRandom variation birth/death rates– ““good” years and “bad” yearsgood” years and “bad” years

EXTINCTION EXTINCTION PROCESSES PROCESSES

Rare species are at risk due toRare species are at risk due to::– genetic stochasticitygenetic stochasticity

Random variation in gene freq. due Random variation in gene freq. due to:to:

– Genetic driftGenetic drift– BottlenecksBottlenecks– inbreedinginbreeding

EXTINCTION EXTINCTION PROCESSES PROCESSES

A. SpecializationA. Specialization– habitat restrictionhabitat restriction

proboscis monkeys and mangrove proboscis monkeys and mangrove swampsswamps

EXTINCTION EXTINCTION PROCESSES PROCESSES

A. SpecializationA. Specialization– habitat habitat

restrictionrestriction– range range

restrictionrestriction golden-lion golden-lion

tamarinstamarins

EXTINCTION EXTINCTION PROCESSES PROCESSES

A. SpecializationA. Specialization– habitat habitat

restrictionrestriction– range range

restrictionrestriction– body size and body size and

home-range home-range sizesize

maned wolfmaned wolf

Photo by Pete Oxford

EXTINCTION EXTINCTION PROCESSES PROCESSES

A. SpecializationA. Specialization

B. CatastrophesB. Catastrophes– earthquakes, asteroidsearthquakes, asteroids– 5 mass extinctions5 mass extinctions– Cretaceous-Tertiary Cretaceous-Tertiary

extinctionsextinctions

EXTINCTION EXTINCTION PROCESSES PROCESSES

A. SpecializationA. Specialization

B. CatastrophesB. Catastrophes– the human catastrophethe human catastrophe– humans have caused 75% of humans have caused 75% of

extinctions since 1600extinctions since 1600

HUMANS AND HUMANS AND EXTINCTION EXTINCTION

A. Role of OverexploitationA. Role of Overexploitation– Lessons from North AmericaLessons from North America

HUMANS AND EXTINCTION

HUMANS AND EXTINCTION

A. Role of Overexploitation– Bison

A. Role of Overexploitation– Bison

• presettlement: ca. 60 millionpresettlement: ca. 60 million• used food, hidesused food, hides• weapon against Native weapon against Native AmericansAmericans• by 1889: only 600by 1889: only 600

HUMANS AND HUMANS AND EXTINCTION EXTINCTION

A. Role of OverexploitationA. Role of Overexploitation

B. Role of ExoticsB. Role of Exotics– introduced organismsintroduced organisms– cause of 20% of extinctions cause of 20% of extinctions

since 1600since 1600

HUMANS AND HUMANS AND EXTINCTION EXTINCTION

B. Role of ExoticsB. Role of Exotics– Feral PigsFeral Pigs

game speciesgame species destroy destroy

understory and understory and groundcovergroundcover

effect on brown effect on brown honeycreeperhoneycreeper

expensive to expensive to exterminateexterminate

Po’ouli, n = 3 on 2/03

HUMANS AND HUMANS AND EXTINCTION EXTINCTION

B. Role of ExoticsB. Role of Exotics– Domestic CatsDomestic Cats

domesticated to domesticated to kill pestskill pests

in 1/3 of U.S. in 1/3 of U.S. householdshouseholds

humans support humans support high densitieshigh densities

HUMANS AND HUMANS AND EXTINCTION EXTINCTION

Cats: Cats: Effects on Native WildlifeEffects on Native Wildlife– WisconsinWisconsin: 19 million songbirds, : 19 million songbirds,

140,000 game birds per year140,000 game birds per year– Great BritainGreat Britain: 50 million small : 50 million small

mammals per yearmammals per year– AustraliaAustralia: endangerment of eastern : endangerment of eastern

barred bandicootbarred bandicoot

Photo: Ian McCann

HUMANS AND HUMANS AND EXTINCTION EXTINCTION

C. Role of Human Population C. Role of Human Population SizeSize– most abundant mammal most abundant mammal

(Suzuki)(Suzuki)– currently about 6.7 billioncurrently about 6.7 billion– stabilize at ~9 billion by 2042stabilize at ~9 billion by 2042

HUMANS AND HUMANS AND EXTINCTIONEXTINCTION

C. Role of Human Population SizeC. Role of Human Population Size– Habitat DestructionHabitat Destruction– Habitat DisturbanceHabitat Disturbance– The “human footprint” on habitats The “human footprint” on habitats

is today’s biggest threat to is today’s biggest threat to mammalsmammals1.1. Human densityHuman density2.2. Land transformationLand transformation3.3. Access to areasAccess to areas4.4. Electrical power infrastructureElectrical power infrastructure

CONSERVATION AND CONSERVATION AND HUMAN RESOURCE USEHUMAN RESOURCE USE

Humans use ca. 40% of total terrestrial Humans use ca. 40% of total terrestrial NPPNPP

www.usda.gov

CONSERVATION AND CONSERVATION AND HUMAN RESOURCE USEHUMAN RESOURCE USE Humans use ca. 40% of total terrestrial Humans use ca. 40% of total terrestrial

productivityproductivity Land pre-empted for agriculture and cities: Land pre-empted for agriculture and cities:

extinction of 5% of land mammalsextinction of 5% of land mammals

Richmond, VA – USDA photo

CONSERVATION AND CONSERVATION AND HUMAN RESOURCE USEHUMAN RESOURCE USE Humans use 20-30% of total terrestrial Humans use 20-30% of total terrestrial

productivityproductivity Agriculture pre-emption: extinction of 5%Agriculture pre-emption: extinction of 5% Energy pre-emption: extinction of 10% more of Energy pre-emption: extinction of 10% more of

land mammalsland mammals

Texas oil wells Russian coal power plant

CONCLUSIONCONCLUSION

Conservation will fail unless:Conservation will fail unless:– human population is controlledhuman population is controlled– human resource use is moderatedhuman resource use is moderated