19.2 causes of the gene pool change

mutation

leads to new alleles which means there are more recessive alleles showing. some can have advantages. back mutations can occur to reverse the effect of the initial mutation

gene flow

movement of alleles from one population to another(immigration/ emigration). can increase diversity in nearby populations. reduces genetic diversity between populations.

non random mating

selected individuals have a better chance of mating than others. some phenotypes will increase. inbreeding increase HR

genetic drift

affects small populations. change in allele frequency due to chance

founder effect

occurs when a new isolated populations develops from a small #. the founding individuals don’t represent the entire gene pool. rare alleles can be more common and some alleles can be lost.

the bottleneck effect

occurs when there’s a fast decrease in population size and only some individuals can pass on the gene. caused by disease, humans, natural disasters, starvation. low genetic diversity. mostly seen in species that are close to extinction

natural selection

organisms that survive pass down their genes, increasing their allele frequencies. environment can give some phenotypes a see time advantage, greater fitness. lots of genetic diversity

sexual selection

results from non random mating. species mate with individuals who have a specific trait.

heterozygous advantage

individuals carrying on copy of each allele (H) have a survival advantage over HD or HR

habitat fragmentation

large continuous habitats are split due to humans. prevents gene flow between populations. habitat destruction can cause the bottleneck effect