WFC 154 Flashcards
Biological species concept
A species is a group of organisms that can interbreed and produce fertile offspring
Morphological species concept
organisms are grouped by appearance or physiology
Phylogenetic species concept
organisms with a shared evolutionary lineage that can be differentiated from others based on a common trait or gene
Cons of Biological species concept
does not account for asexual organisms
Cons for morphological species concept
Arbitrary distinctions:
1)Similar species can look identical but have different behaviors
2)One species can have a variety of sizes and morphs that make it hard to classify them as the same species
Cons of phylogenetic species concept
WHEN is it a species?
How many species are there?
~2 million discovered but it’s possibly between 2-100 million on earth overall
Where are most species concentrated?
Tropical rainforest and coral reefs
Species richness
number of species at a site
Simpson diversity
accounts for abundance
y-diversity
total regional diversity
b-diversity
the proportion of unshared species between communities
Species-area approach
more habitat=more species
Larger areas have more species because :
> more types of habitats and local environments
>greater separation of populations means more speciation occurs
>larger populations have fewer extinction
Extinction Debt
predicted eventual loss of unviable populations; extinction takes a while
Problems with the species-area approach
1) extinction may be slower than habitat restoration (extinction debt can work for us)
2) species can often persist once habitats are converted
What percent of species that have ever lived are extinct?
99%
What geologic epoch had the most species alive during it?
todays
Mass extinction
a period with severe species loss
how many mass extinctions were there?
5
All five of the historic mass extinctions were followed by_______
Mass speciation
It takes ______ years to recover the lost diversity after mass extinction events
50-100 million years
What do we need to know in order to determine if we are in a mass extinction?
- “background” rate of extinction
- current rate of extinction
Background rate of extinction
the average rate at which species fo extinct
The Overkill Hypothesis + evidence
humans could be responsible for Pleistocene extinctions across the world.
Evidence: human arrival often correlates with dramatic wildlife declines
What are the 4 notable modern extinctions?
- Thylacine; caused by poaching and competition with dogs
- Passenger Pigeon; caused by habitat loss and hunting
- Lyall’s wren; cat predation
- Golden Toad; Chytridiomycosis
What traits do vulnerable species share?
- large body size
- small range size
- small population sizr
4.habitat or diet specialist
