11. Extinction Flashcards
Extirpation
Extinction of one or more sub-populations
- Loss of genetic diversity
Functionally Extinct
A species which has members present in environment but greatly reduced in numbers compared to the ancestral population
- Below minimum viable population
Extinct in the Wild
Only in captivity
- Most species don’t breed well
- Genetic diversity is a fraction
Extinction
Death of the last individual of the species
- Difficult to prove a negative
Demonstrating Extinction
Successive searches throughout native range
- Different agencies disagree what is “Thorough search”
Background rate of extinction
Taxon-specific
Average rate of extinction of a species
Tracking species extinctions
Fossil record
- The history told by the accumulated fossil
Estimating the rate of extinction
Examining extinctions through the fossil record
- Fossil record is biased
Usually measured at family level
Bias of fossil record
- Fossil formation ins not possible in all environments
- Soft bodied organisms do not preserve well
Traits and Extinction
Large body size at maturity
- More time to mature and reproduce - Harder to recover from a die-off
At near or top of food chain
- Harder for predator to find enough food
Rare
- Fewer individuals
Limited Range
- Chance events (hurricanes etc) can drive extinction
Specialized lifestyle
- Specific environment required
Asexual
- Muller’s Ratchet
Muller’s Ratchet
Deleterious mutations build up in asexual population
Coextinction
Extinction of one species cause the extinction of the other
- Often seen in obligate mutualism
Lazarus Taxa
Thought to be extinct but rediscovered
Pseudoextinction
A species thought to be extinct but later found to have evolved into another species or sub-species
De-extinction
Intentionally bringing back extinct species through genetic engineering
- Genetic diversity still very low
