Exam Two Flashcards
What is a gene pool?
All the genes in a population
What are the conditions for the Hardy-Weinberg Equillibrium?
No natural selection Random mating Large population No mutaion No migration
What is soft selection?
An individual will not have as many offspring
What is hard selection?
An individual will not have any offspring
What is gene flow?
Flow of genes in and out of gene pool
What is the island continent model?
Individuals can move from the island to the continent and not affect the gene pool, however, if an individual moves from the continent to the island the gene pool will be changed
What reduces the difference between two populations?
Migration
What must be interrupted in order for speciation to occur?
Gene flow
What is the founder effect?
A small population will have a distinctly different gene pool from the original genepool
What is genetic drift?
Random fluctuation in allele frequencies due to sampling effects in finite populations
Allele frequencies fluctuate over time
What is observed heterozygosity?
The fraction of individuals that are heterozygous at a particular locus
What is expected heterozygosity?
Fraction of heterozygotes expected under the Hardy-weinberg model
How can you tell if heterozygotes are at an advantage in a population?
If observed is greater than expected
What is runaway sexual selection?
One trait is desired so females choose that so their sons will reproduce, trait then becomes excessive
What is the handicap principle hypothesis?
Elaborate displays would result in the death of the organism if they were not in good condition, therefore those with the best displays are in the best condition
What is the parasite load hypothesis?
High parasite loads decrease a males ability and it is represented in a trait
What is intersexual selection?
Female chooses the males to mate with
What is intrasexual selection?
Males compete for the chance to mate with a female
Leads to size dimorphism
What are quantitative traits?
Continuously variable traits
Polygenic
Multifactorial: Enviornmental influences
What does it mean to be polygenic?
Trait is influenced by several to many genes
What is directional selection?
Organisms at one end of the bell curve are most likely to reproduce
What is stabilizing selection?
Organisms in the center of the bell curve are most likely to reproduce
What is disruptive selection?
Organisms at both ends of the bell curve are most likely to reproduce
What is the neutral theory of molecular evolution?
Most variation present within a population is selectively neutral
Who created the idea of neutral theory of molecular evolution?
M Kimura
What are pseudogenes?
Nonfunction, untranslated regions of the genome
What is genetic equidistance?
If molecular evolution proceeds at the same rate over time, then all members of a clade should be equidistant from an outgroup
What is the molecular clock?
If we know the substitution rate then we can determine the distance between two species
What is the problem with the molecular clock theory?
Not all loci evolve at the same rate
Not all lineages evolve at the same rate\
Saturation
What are the four ways that genetic variation can enter a population?
Recombination
Mutation
Migration
Lateral gene transfer
What is population genetics?
Studies how the genotype frequencies in an offspring population are related to the parental population
What are the three conclusions that the Hardy-Weinberg equilibrium provides?
- The frequencies of A1 and A2 do not change over time
- Given allele frequencies, we can predict the equilibrium genotype frequencies
- If no evolutionary processes are operating, a locus that is not at equilibrium will reach equillibriim
What is underdominance
The A1A2 heterozygote has a lower fitness than either A1A2 genotype
What is overdominance?
Heterozygote is at an advantage,
Also called heterozygote advantage
What is selective neutrality?
There is no fitness difference between the two alleles
