Ex. 10 Population Genetics and Evolution Flashcards
what is population genetics?
branch of biology concerned with genetic changes in populations (in particular, changes in the gene pool over time)
define gene pool
the collection of all genes carried by individuals in a population
in what two terms is the gene pool described by?
- allele frequencies
2. genotype frequencies
what are 4 evolutionary agents that influence population genetics?
- mutations
- gene flow
- genetic drift
- natural selection
what are mutations?
- biochemical changes in the genetic material of an organism
- happen at very slow rates
- most important source of genetic variation in the gene pool!
what is gene flow?
emigration or immigration of genes out of/into the population
what is genetic drift?
- variation in the relative frequency of different genotypes in a small population ( caused by chance disappearance of particular genes as individuals die or do not reproduce)
- genetic drift decreases as population size increases
when does natural selection occur?
occurs when a particular phenotype has a greater (or less) reproductive success than an alternate phenotype
(determined by 1. survive to reproductive age AND 2. ability to produce viable offspring)
what are the 5 assumptions of the hardy-weinberg principle?
- equal chances of survival/reproduction
- no immigration or emigration
- no mutations
- must have large population (no genetic drift occurring)
- must mate at random
what can we assume about gene frequencies if a population is in Hardy-Weinberg equilibrium?
- we can calculate expected genotype frequencies for the next generation by looking at allele frequencies AND we know that these frequencies will remain constant
- recombination (from meiosis and mitosis) does not change the overall composition of the gene pool all by itself
