deck 2 Flashcards
What is Genetic drift?
when allele frequencies change at random WITHOUT RESPECT TO FITNESS.
What are genetic drift special cases?
- Founder Effect
- Genetic Bottleneck
What is Founder Effect?
When a small group of individuals immigrate to new geographic area and establish a new population, the allele frequencies in the new population are guaranteed to be different from the source population.
What is Bottleneck Effect ?
A sudden reduction in the diversity of alleles in a population.
Natural catastrophes such as floods or fires or storms, as well as human-caused catastrophes like deforestation can cause bottleneck
What is Gene Flow?
The movement of alleles into (IMMIGRATION) or out of (EMIGRATION) populations.
what is Biological Species Concept?
A species is a reproductively isolated population that can’t produce viable offspring with any other population.
what is morphospecies concept?
Recognizes species based on similarity of traits.
what is phylogenetic species concept?
Defines species based on evolutionary history.
SMALLEST BRANCH ON MONOPHYLETIC TREE.
what are Disadvantages of Biological Species Concept?
- DOESN’T WORK FOR BACTERIA or ANYTHING EXTINCT
- Difficult to assess if populations do not overlap geographically.
what are Disadvantages of morphospecies Concept?
Doesn’t work if behavioral traits prevent reproduction.
Might lead to calling two different species the same if you pick the wrong trait.
what are advantages of phylogenetic species Concept?
Applicable to fossils and asexual things
what are advantages of morphospecies Concept?
Works well for fossils (Widely applicable)
what are advantages of Biological Species Concept?
[Most intuitive] - Works for most anything reproducing sexually
- Evolutionary independence
what is sympatric speciation?
Speciation occurring even if the individuals are not split and theoretically capable of interbreeding.
what are two ways sympatric speciation can occur?
1) Disruptive selective and niche differentiation
2) Polyploidization
what is Disruptive selective and niche differentiation?
If parts of the population start using different niches, and selection acts on them, they can become reproductively isolated in the same place
what is polyploidization?
increases in the number of chromosome sets.
what is allopatric speciation?
Speciation due to geographic isolation.
what are two ways allopatric speciation can occur?
- Dispersal
- Vicariance
what is dispersal and vicariance?
Individuals disperse from their population and colonize a new habitat.
what are two types of reproductive barrier?
pre and postzygotic
what is prezygotic?
presents zygotes from forming
what is temporal (prezygotic barrier)?
Populations are isolated because they breed at different times.
what is habitat (prezygotic barrier)?
Populations are isolated because they breed in different habitats.
what is behavioral (prezygotic barrier)?
Populations do not interbreed because their courtship displays differ.
what are postzygotic barriers?
Zygotes are inviable or hybrids are sterile.
what is hybrid viability (postzygotic barrier)?
Hybrid offspring do not develop normally and die as embryos.
what is hybrid sterility (postzygotic barrier)?
Hybrid offspring mature but are sterile as adults.
