Ecology- Ch. 9: HIPPCO

3 levels of extinction

Local, ecological, biological

Local Extinction

species dies out in one area but is still found elsewhere

Ecological/ functional extinction

when so few members of a species are left that they cannot fulfill their role in the biological communities where they are found

Biological extinction

a species no longer found on earth

this extinction is forever (or is it?)

Background extinction

natural rate of species extinction averaging ~1 species per million/ year

extinction rate

the continues, low-level extinction of species

one species per million species every year would be 1/ 1000000 per year (0.0001%)- this was the estimation for earth before humans show up

Mass extinction

when many species die off (75% or more) in a geological short period of time

by the end of the century it is predicted that there will be an extinction in the wild of about ¼ of known species

in what ways are humans causing a sixth mass extinction

destroy habitats, outcompete other species, overharvest other species, introduce invasive species

how many mass extinctions have there been, and why did they happen

five; natural causes with global changes to the environment conditions

Why is preventing extinction important?

1. Their biodiversity including the Genetic codes are important pharmacologically as treatments and medicine ( use value)

2. Play important biological roles in food webs ( eat many insects and are eaten by many predators, especially reptiles, birds, and mammals) (use value

3. as biological indicators, they serve as harbingers of environmental deterioration

Use Value

a species usefulness to us in directly providing ecological and environmental services for us

what economic and ecological service do birds perform

control populations of rodents and insects

pollinate and spread plant’s seeds

remove dead animal carcasses

vulture population and drop

1990s~40 million individuals of three specific vulture species in India and South Asia

population dropped 97% in a few years

what caused the vulture numbers to drop?

they were poisoned by diclofenac (boost milk production in cows) which causes kidney failure in vultures

what did the decrease in vultures affect?

cow carcasses increase, wild dog and rat populations exploded, dogs with rabies increase

1997~ 30,000 people died in India from rabies ( over half the world’s rabies deaths that year)

Indicator Species

provide warnings of damage to the ecosystem

trout- require clean water with high O2

birds- enormous geographical range and response to habitat fragmentation and chemical disturbances

butterflies- association with plants species

amphibians- porous skin responds to pollutants, especially aquatic ones

threatened species

still has an abundant population, though it is declining and thus at risk to become endangered

endangered species

so few individuals that the species could become extinct over all or most of its natural range

vanishing amphibians

eggs have no protective shell to UV radiation or chemical pollution

as tadpoles they are subject to fertilizers

as adults they are subject to pesticides and chemical pollution

since 1980 roughly 6,000 species have declined

2004~ global amphibian assessment suggests 33% of amphibian species are endangered with extinction and another 33% are declining in number, mainly in the Caribbean

reasons for decline in amphibians

habitat loss/ fragmentation by draining/filling wetlands and deforestation for urbanization

prolonged droughts because of changing weather patterns

pollution, especially pesticides, make them vulnerable to infections

UV radiation caused by ozone depletion in the stratosphere- CFCs

parasitic infection at the egg/larval stages

viral/fungal infections

• chytrid fungi attacks the skin of frogs and salamanders decreasing their ability to take in water so they dehydrate

• spread when they congregate for breeding

climate change- Harlequin frogs in Panama and the Golden Toad of Costa Rica

overhunting- Asia and France for food/ exotic pet trade

Introduction, human or natural, or non-native species that either “eat or out-compete” and spread disease

characteristics linked to higher extinction rates

low reproduction rate

specialized niche

narrow distribution

feeds at high trophic levels

fixed migratory patterns

rare

commercially valuable

large territories

what does HIPPCO stand for?

habitat destruction/degradation/fragmentation

invasive species

population and resource use growth

pollution

climate change

overexploitation

what are the 3 main reasons for accelerated species extinction

1. Habitat destruction

2. over-harvesting of species (particularly aquatic species)

   1. introduced/invasive species

Habitat loss

deforestation of the rainforest is the biggest eliminator of species

destruction and degradation of coral reefs and wetlands, plowing of grasslands and destruction of aquatic ecosystems

in the temperate zones more in the last 200 years but lately is shifting to the tropical zones

island species are especially vulnerable- 63% of Hawaii’s species are at risk

Habitat islands

habitats surrounded by a different type of habitat

national parks/ nature preserves surrounded by urban and suburban development

freshwater lakes and mountain biomes are as well

Habitat fragmentation

separating of a large continuous habitat into smaller, distantly isolated ones

roads, logging, agriculture, and urban development cause

how does habitat fragmentation affect species

blocked migration routes, divided populations/ gene pools, smaller isolated populations which are susceptible to predators, competitors, and disease

fragmentation is dangerous for rare species, require large areas for hunting, species with lose reproductive capacity, or specialized niches

Species introduction

some are deliberately introduced

85% of the world’s tree plantations grow non-native trees for timber/beauty/ gardens- many introduced species have no predators, competitors, parasites to keep their population in check

Giant African land snail

introduced in Brazil for escargot, eats everything and carries meningitis and the other ruptures your intestines

Argentinian fire ant

show up in Alabama, no natural predators and wipe out 90% of native ant species

killed 80 people because of allergic reaction to venom

6.7 billion in economic damage per year

widespread pesticides killed native ant species which competed with them, the fire ants became resistant to the pesticides through natural selection

Kudzu vine

introduced in the 1930s to help with erosion- but it’s hard to kill and takes over everything, trees, abandoned cars, and houses, hillsides

with climate change, it could reach the great lakes by 2050