Lecture 11 Ricklefs Reading

Chapter 6 (115-124) and Chapter 21 (276-279)

-Genotype - all of an individual's genes or the set of genetic instructions. Phenotype - the outward expression of the genotype in the individual's structure and function or the expression of the genotype. This can respond to variation in the environment. Phenotypic plasticity is the capacity of an individual to exhibit different responses to the environment.
-Alleles are different forms of a particular gene.
-Heterozygous-an individual with 2 different alleles of a particular gene, one dominant and one recessive.
-Homozygous - both copies of a gene are the same, both dominant or both recessive.
-Gene pool - constituted by all the alleles of all the genes of every individual in a population.
-Mutations are a source of genetic variation.
-The process of evolution by natural selection has 3 main ingredients: variation among individuals, inheritance of that variation, and differences in survival and reproductive success, or fitness, related to that variation.
-Natural selection - the traits of those individuals that leave the most offspring are said to be selected, and the differential survival and reproduction of individuals having different traits. Can be stabilizing - maintain average or optimal phenotypes in a population. Can be directional - shifts the phenotype toward a new optimum. Can be disruptive - increases the genetic and phenotypic variation within a population and creation of a bimodal distribution of phenotypes with peaks toward both ends of the original distribution.
-Artificial selection - the result of conscious decisions made by humans concerning desirable qualities of domesticated or lab animals and crops.
-Population genetics has produced various math models that allow us to predict changes in gene frequencies.

-Genetic drift in small populations causes loss of genetic variation.
-Coalescence time - in small populations, just by chance, all copies of a gene are descended from a single common ancestor existing at this time.
-Coalescence happens throughout the genome and a certain level of inbreeding is disastrous for natural populations.
-Genetic drift - the process by which allele frequencies change and genetic variation is lost due to random variations in fecundity, mortality, and inheritence of gene copies through male and female gametes.
-Founder events - a a single episode of small population size can reduce genetic variation in the colonizing population.
-Population bottleneck - situation where continued existence of the population at small sizes results in further loss of genetic variation due to genetic drift.
-Effective population size - the size of an ideal population that undergoes genetic drift at teh same rate as an observed population.

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