Foundations of Biology Final Exam: Ch 23.4

genetic drift

change in allele frequencies in population due to chance; can lead to decrease in genetic varitation causes allele frequencies to change ("drift") up and down randomly; occurs in every population

fitness; small

genetic drift is random with respect to _______ and most pronounced in _______ populations

bottleneck

general definition; a temporary reduction in population size; most genetic variation is lost; usually population is cut by the environment changing

founder effect

occurs when a group of individuals establish a new population in a new area which results in a change of allele frequencies and evolution through genetic drift; common is colonizing isolated habitats i.e. islands

population bottleneck

sudden decrease in population size in a large population; commonly caused by disease outbreaks and natural catastrophes

genetic bottleneck

often caused by a population bottleneck; a sudden reduction in the number of alleles in a population; genetic drift occurs during this

gene flow

movement of alleles between populations; occurs when individuals leave one population, join another, and breed; equalizes allele frequencies between source and recipient populations; homogenizes allele frequencies among populations

mutation

generates genetic diversity; creates new alleles, not only new combinations of alleles; the ultimate source of variation in biology

point mutation

change in a single base pair in DNA; may result in the same, similar or different amino acid in a polypeptide; may change the regulation of the expression of other genes

chromosome-level mutation

change in the number or composition of chromosomes, such as gene and genome duplication

lateral gene transfer

movement of genes between different "species"; might be important source of genetic variation, especially in prokaryotes, but sometimes eukaryotes

random

mutation is ________ with respect to fitness of individual

purifying

a type of selection that removes deleterious alleles that lower fitness from a population

prokaryotes

mutations can be a significant evolutionary force in ________ because they have very short generation times