Evolution of Populations - H Bio Werner

genetic drift

random changes to allele frequencies that have larger affects to small populations because there are less available mates and choices are limited

bottleneck effect (GD)

a large decrease in population size over many generations due to an outside factor (hunting, disease, famine, etc)

founder effect (GD)

a small group of individuals in a population emigrate and begin a population in a new location

inbreeding (GD)

a population is so small and isolated that the individuals have no choice but to have offspring within the family/population

artificial selection

breeding animal with good trait with other animal with good trait

directional selection

an extreme phenotype has a higher fitness than any other phenotypes on the curve (peak to left or right instead of middle)

stabilizing selection

phenotypes that fall in the center of the curve are more fit and favored compared to the extremes

disruptive selection

the phenotypes that fall at both extremes are favored/more fit than the phenotypes in the center of the curve

speciation

creation of a new species

species

a group of individuals that are similar both genetically and physically and can reproduce to have fertile offspring

temporal reproductive isolation

2 or more species live in the same habitat but mate at different times of the year

behavioral reproductive isolation

mating ritual

habitat reproductive isolation

2 organisms are adapted to their own specific habitat and need to be there in order to survive

embryological reproductive isolation

the sperm is unable to fertilize the egg or the embryo created does not survive

mechanical reproductive isolation

the 2 species are physically unable to mate and reproduce

geographic isolation definition

a physical geographic barrier separates 2 or more populations from each other and causes the populations to be unable to reproduce

allopatric geographic isolation

an outside factor, like a geographic barrier, prevents 2 or more groups from mating together regularly (like a river) (most common)

parapatric geographic isolation

-a continuously distributed population with no extrinsic barrier to gene flow

-individuals do not mate randomly and are more likely to mate w their neighbors

peripatric geographic isolation

small population isolated at the edge of a larger population (leads to the founder effect)

sympatric speciation

2 or more different species are evolving in the same habitat due to isolation mechanisms that prevent mating and/or fertilization from ever occurring

-does not require large scale geographic distance to reduce gene flow between parts of a population

gradualism

idea that species constantly change and die off, causing the older variations to change into new ones

punctuated equilibrium

idea that species can rapidly mutate and change with long periods of stable life

adaptive radiation

one species evolves into several distinct species that are adapted to their own specific niches

convergent evolution

unrelated organisms evolve to similar niches and develop similar adaptations and characteristics

coevolution

the process by which 2 species evolve “together” in response to change in each other over time

molecular evolution

when genes cross over during meiosis and an unequal swap occurs and gives one of the chromosomes an extra copy of one or more genes

hox genes

master control genes that are not affected by any other genes