ENVS 1100 Lecture Notes - Lecture 11: Living Planet Index, Invasive Species, Sea Mink
3 May 2018
School
Department
Course
Professor
Species Invasion and Extinction
October 14 &15, 2014
Why do evolutionary rates differ? Why can’t all species adjust to changed in their
environment an avoid extinction?
Extinction can occur quickly if the rate of change exceeds the ability of a
population to adapt.
More than 99% of all species that have ever lived on this planet have gone extinct.
Today, most scientists agree we are witnessing a mass extinction, largely driven by
human actions (habitat destruction/fragmentation, climate change, overharvesting).
Most scientists also agree that extinction rates are accelerating worldwide –
although they disagree about the exact rate.
By changing an environment rapidly, humans apply new selective pressures to an
environment (ex. Introducing tree snakes to Guam).
Our changes can be so great that natural selection cant keep up and a population
collapses.
Biodiversity Loss
• Extinction
o Sea mink – overharvesting for fur trade
• Extirpation
o Eastern Wolf – bounties were offered for animal
• Endangered
• Threatened
Extinction
• Background rate of extinction
• 5 mass extinctions during Earth’s history
• ~99% of all species that ever lived are extinct
Current Extinction Rate:
• 100-1000x background level
• Decrease in genetic diversity, population and species richness
• IUCN Red List of species threatened with extinction
o 23% (1093) mammals
o 12% (1206) bird species
Some Species are More Vulnerable than Others due to:
• Rarity of species (ex. Endemic)
• Narrow habitat range
• Large area requirements
• Low reproduction rates
• Extreme specialization/co-evolution dependence
Biodiversity Loss
• Declines in population size
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Why can"t all species adjust to changed in their. More than 99% of all species that have ever lived on this planet have gone extinct. Today, most scientists agree we are witnessing a mass extinction, largely driven by human actions (habitat destruction/fragmentation, climate change, overharvesting). Most scientists also agree that extinction rates are accelerating worldwide although they disagree about the exact rate. By changing an environment rapidly, humans apply new selective pressures to an environment (ex. Our changes can be so great that natural selection cant keep up and a population collapses. Biodiversity loss: extinction, sea mink overharvesting for fur trade, eastern wolf bounties were offered for animal, extirpation, endangered, threatened. Extinction: background rate of extinction, 5 mass extinctions during earth"s history, ~99% of all species that ever lived are extinct. Current extinction rate: 100-1000x background level, decrease in genetic diversity, population and species richness. Iucn red list of species threatened with extinction: 23% (1093) mammals, 12% (1206) bird species.
