Evolutionary Biology 1 Flashcards
Adaptation
A characteristic that increases survival rate / fitness
Hardy Weinburg Equilibrium
When allele and genotype frequencies stay constant in a population between generations
What disrupts HW equilibrium
Mutation
Genetic drift
Gene flow (migration)
Natural selection
Natural selection + an example
Differential survival in a group of entities that differ in one or more characteristic
Endlers (1980) Guppys with red spot, beneficial for attracting females introduction of a new predator caused split reaction in population.
Fitness
Probability of survival x average number of offspring
Problems with detecting Natural Selection
Genetic drift can spread traits
Ancestral state (exaptation)
Selection can not cause change
Gene linkage
what will Natural selection NOT do
- lead to adaption
- produce perfection
- result in progress
- produce a balanced world
Linkage disequilibrium (LD)
alleles appearing together more often than you would expect
Cause of linkage disequilibrium
beneficial alleles grouping together
structural changes (e.g. inversions)
Hitchhiking alleles
Exaptation
When the function of an ancestral trait changes from initial purpose
Genetic Drift
Change in gene frequency in a population s due to the random sampling of organisms and chance involved in the passing on of genes
Selective sweep
the reduction of variation among the nucleotides near a mutation in DNA. It results from a beneficial allele’s having recently reached fixation due to strong positive natural selection.
fixation
The change in a gene pool from two gene variants (alleles) to only one variant (allele)
Hitchhiking genes
when an allele changes frequency because it is near another gene undergoing a selective sweep. - note hitchiking genes can be deleterious.
