evolution 2 Flashcards
Gene pool
A gene pool is all the sets of genes and their different alleles present in an interbreeding population.
When/how do new allele combinations in individuals occur?
New allele combinations in individuals occur through crossing over and random orientation of homologous chromosomes during meiosis and the fusing of genes from the 2 parents
Stabilising selection
Stabilising selection occurs when existing, beneficial variations are already common and they continue to dominate the gene pool.
Directional selection
Directional selection occurs when one extreme trait offers a survival or reproductive advantage. It usually is a result of a change in the environment.
Disruptive selection
Disruptive selection occurs when the most frequent phenotype becomes a disadvantage. The population may break into two groups if this happens.
Reproductive isolation
Reproductive isolation is the failure of individuals from two populations to produce fertile offspring, reducing gene flow between the populations.
Geographic isolation
Geographic isolation is the separation of populations by a physical barrier that reduces gene flow.
Allopatric speciation
Allopatric speciation is when a new species develops from a population becoming geographically isolated from other populations.
Behavioral isolation
Behavioral isolation is a behaviour that reduces gene flow between part of a population.
Sympatric speciation
Sympatric speciation is when part of a population develops into a new species while living in the same geographic area as its ancestral population.
Temporal isolation
Temporal isolation is a shift in the timing of a behavior (mating) that reduces gene flow between part of a population.
Gradualism versus punctuated equilibrium
Gradualism is evolution occuring from slowly from minor changes whereas punctuated equilibrium evolution occurring rapidly.
Polyploidy
Polyploidy is the presence of more than 2 complete sets of chromosomes in a cell.
