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
Phenetic species concept?
Species are defined using morphological traits.
Disadvantages to the phenetic species concept?
*Members of the same species can be morphologically distinct
*Cryptic species: morphologically similar but genetically distinct
*Concept relies on human interpretation to define species.
Phylogenetic species concept?
Species are the smallest possible groups whose members are descended from a common ancestor and all possess characteristics that distinguish them from other groups.
Biological species concept?
Species are a group of actually or potentially interbreeding populations that are reproductively isolated from other groups.
Advantages with the biological species concept?
*No trouble with different morphs within a species or cryptic species
*Does not require human interpretation of morphology or detailed phylogenetic information.
Disadvantages to the biological species concept?
*What is meant by potentially interbreeding?
*Not useful for ancient species
*Not possible for asexual species
What if populations don’t overlap in the wild but will breed in captivity?
What if they produce offspring but those offspring are infertile or unhealthy?
General lineage species concept?
Species are metapopulations that exchange allele frequently enough that they comprise the same gene pool and the same evolutionary lineage. If individuals are in the same gene pool, they are considered the same species.
Fused populations?
If divergence in allopatry results in no pre zygotic or post zygotic isolation, and the geographic barrier is removed, ten fusion will result.
