13 Flashcards
Mechanisms of speciation?
*Barrier to gene flor between diverging populations.
Extrinsic barriers?
Geographical barriers
Reproductive barriers (intrinsic)?
Cannot physically mate
Allopatric speciation?
When populations are separated by an extrinsic geographic barrier.
Peripatric speciation?
Small number of individuals are separated from the main population.
Vicariance?
The formation of geographic barriers that separate a population.
Parapatric speciation?
When species are spread out over a large geographic area, but mate only with those that live close to them.
Sympatric speciation?
If some individuals begin to exploit a new niche, and mate only with others that do the same.
Prezygotic barriers?
Occur prior to the fertilization of the egg and the production of the zygote.
Prezygotic isolation?
Habitat isolation
Pollinator isolation?
Species pollinated by different organisms.
Behavioural isolation?
Species utilize a different “mate recognition system”
Copulatory behavioural isolation?
During copulation, makes may need to perform behaviours that entice the female into allowing mating to occur.
Mechanical isolation.
Species genitalia not compatible.
Gametic isolation?
Species gametes not compatible
Postzygotic isolation avoids selection for?
hybrids
Ecological hybrid inviability?
Hybrids have lower survival in parent habitat
Behavioural sterility?
Hybrids can’t obtain mates
Primary hybrid zone?
Two separate populations that continue to mate and produce hybrids.
Secondary hybrid zone?
Two populations that have been physically separated via allopatric come back together.
Reinforcement?
The increase of reproductive isolation between hybridizing populations through selection against hybrid offspring.
Selection prefer?
Prezygotic barriers.
About how many eukaryote species are known today?
1.9 million
How many eukaryotic species do we predict?
5-10 million