Biodiversity Flashcards
How are the Biases corrected?
Count Families not Species, Throw out Single occurrences since we don’t know if it was really a species or not, Scale by rock volume as the thicker rock mass is more accurate, Exclude recently derived taxa
What are the 4 Biases of Biodiversity?
Missing species, single occurrence, better fossil record for more recent taxa, older species are more likely to go extinct
Is Biodiversity increasing over time?
Yes
Possible explanations for increase in Biodiversity?
- Accumulation of species through speciation. 2. Increasing species overtime because of decline in extinction rate
Explanation for extinction rates declining?
Species have more members, it takes longer for all member to go extinct. Early taxa are wiped out early before they become established.
Taxa with high speciation events have _______ extinction rates. Why?
High.
Species become so specialized that it takes a very small environmental change to knock them out.
Degree of Specialization in relation to extinction rates
Highly specialized populations more likely to spectate. Because they are specialized they are distributed in patchy regions, isolated from gene flow and avoid competition. More vulnerable to environmental change.
Population size in relation to extinction rates
Small size or fluctuating size are more vulnerable to extinction
Geographic Range in relation to extinction rates.
Broad range have lower risk to extinction, not wiped out by local environmental change.
Causes of extinction?
failure to adapt to changes in environment, loss of environment reduces population size, lack of genetic diversity, loss of diversity due to drift, negative feedback “extinction vortex”
Why don’t organisms become less prone to extinction?
Environment is always changing. “Each species has to run as fast as possible just to stay in the same place”
What caused the Permian extinction?
Massive volcanic eruptions, release of methane
What is the impact of mass extinction on biodiversity?
Clears the slate, allows new community structures to emerge. More taxa that are able to homeostatically control their environment. Increase diversity of predators
What factors contribute to speciation?
Opportunity. Ecological space. Vacant niches. Escape from competition.
What are the two models of speciation?
- Competitive Displacement. 2. Replacement after Extinction.
