Biodiversity Chapter 7

Percent of US vegetables that are now extinct

• 97%

Extinct/Globally Extinct

• after a thorough search, no member of the species is found alive anywhere in the world

Example of Globally extinct

• Monteverde golden toad from Costa Rica

Extinct in the Wild

• species only remains alive in captivity or in other human-controlled situations

• Zoos or botanical gardens

Extinct in wild example

• Franklin Tree

Locally extinct or extirpated

• a species no longer found in a specific area it once inhabited but is still found elsewhere in the wild

Locally Extinct example

• purple bladderwort

Regionally Extinct

• species extinct in a country or region but still persists in another part of its range

• Species no longer found in part of its former range but still lives elsewhere

Regionally extinct example

• Gray wolf in west North America but not NE US

Ecologically Extinct

• species persists at such reduced numbers that its effects on other species in its community are negligible

Ecologically extinct

• tigers

Species concern catergories

• extinct

• Endangered

• Vulnerable

• Threatened

• Common

5 mass extinctions

• Ordovician

• Devonian

• Permian

• Triassic

• Cretaceous

6th mass extinction

• 30,000 years ago to present

Extinction debt

• presumed eventual loss of a species following habitat destruction and fragmentation or the inevitable extinction of any species in coming years as a results of current human activities

Extant

• a species that is still alive

Giant tortoise

• extant

Yangtze River Dolphin

• functionally extinct

• Reports critically endangered

Reasons for high extinction rates on islands

1. Limited range

2. Small population sizes

3. Small numbers of populations

4. No defenses for new predators

5. Disease threatens

________ species have higher rates of extinction than _______ species

• island;mainland

_______ species are more vulnerable to extinction than _______ species.

• freshwater;marine

Island Biogeography Model

• distribution of biodiversity on islands

• 1967

• MacArthur and Wilson

• Can estimate future rates of extinctions on islands based on the formula for the relationship between island size and the number of species living on the island

Species area relationship

• the number of species found in an area increases with the size of an area

• More species found on large islands than on small islands

S =

• CAZ

S in species area relationship eq.

• number of species on an island

A in species area relationship eq.

• area of the island

C & Z in species area relationship eq.

• constants that depend on the type of island and the types of species involved

If habitat is reduced by 50%

• 10% of species expected to disappear

If habitat is reduced by 90%

• 50% of species expected to disappear

Assumptions that limit predictions

• estimates are based on typical values for the species area curves

• Assumes all endemic species are eliminated from areas that have been largely cleared of forest

• Assumes the habitat areas are eliminated at random

• Degree of habitat fragmentation may affect extinction rates

7.1 Box

• extinctions of island birds

• Rapid evolution of Hawaiian honeyceeper

• Humans activities make on 17 species remain

• Polynesian species extinctions

• No good coeveolution between brown tree snakes and prey to adapt

Low armored sticklebacks

• smaller spikes

• Less spikes

• Poisoned by lake

• Came back and were repopulating due to faster growth than fully-armored stickle backs

Fully armored stickle backs

• bigger spikes

• More spikes on bottom side

• Populated loberg lake after poisoning

• Numbers decrease due to slow growth following dragonfly predation

Examples of adaptive radiation

• Hawaiian honeycreeper

• Mammals following the death of the dinosaurs

• Finch

KT line

• line in rock found to separate rock where dinosaurs can be found from rock where this no dinosaur

• Layer of iridium above it from asteroid