Unit 7 - Natural Selection

natural selection

natural selection

process where individuals that have inherited certain traits tend to survive and reproduce at a higher rate than others because of those traits

adaptation

characteristic that increases an individual’s ability to survive and reproduce

homologous trait

trait in different species that are similar because of common ancestry

analogous trait

trait with similar function but no common ancestry

convergent evolution

evolution of similar features in independent evolutionary lineages

microevolution

change in allele frequencies in a population

gene pool

set of all genes or genetic info within a population

founder effect

when a few individuals become isolated from a larger population, and whose gene pool is not reflective of the original population

bottleneck effect

when the size of a population is drastically reduced

gene flow

transfer of alleles from one population to another

genetic drift

change in allele frequencies in a population from generation to generation

heterozygote advantage

greater reproductive success of heterozygous individuals compared with homozygous, preserves variation in gene pool

sexual selection

process in which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates

sexual dimorphism

differences in secondary sexual characteristics between biological males and biological females

directional selection

conditions favor individuals exhibiting one extreme of a phenotypic range

disruptive selection

conditions favor individuals at both extremes

stabilizing selection

conditions favor intermediate variant

phylogeny

evolutionary history of a species or group of species

taxonomy

how organisms are named and classified

phylogenetic tree

a branching diagram that represents a hypothesis about the evolutionary history of a group of organisms

taxon

a group forming a unit of classification

branch point

a divergence on a phylogenetic tree of two or more taxa from a common ancestor

basal taxon

a taxon that diverged early in the history of the group

cladistics

a form of classification in which organisms are placed into groups based primarily on common descent

clade

a group of species that includes the ancestral species and all its descendants

shared ancestral character

a character that originated in an ancestor of the taxon

shared derived characteristic

a character unique to a clade

horizontal gene transfer

genetic information transferred in ways other than reproduction

Does King Phillip Come Over For Good Soup?

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

speciation

splitting of one species into two or more species

macroevolution

evolution above species level

reproductive isolation

the existence of biological factors that prevent members of two species from interbreeding and producing viable fertile offspring

prezygotic barriers

prevent fertilization

postzygotic barrier

prevent hybrids from two different species from reproducing

allopatric speciation

new species forms when population is geographically isolated

sympatric speciation

new species forms without geographic isolation

mass extinction

elimination of a large number of species on Earth, resulting from global environmental changes

adaptive radiation

periods of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities