EVOLUTION - SBI3U

evolution

descent with modification

paleontology

the scientific study of fossils

strata

rock layers formed when new layers compress old layers

uniformitarianism

principle: mechanisms of change are constant

catastrophism

principle: past changes were sudden caused by different mechanisms than are operating today

artificial selection

selective breeding of plants and animals by humans to encourage occurrence of desirable traits

natural selection

process: individuals with certain inherited traits tend to survive and reproduce at greater rates than individuals lacking those traits

vestigial

a feature of an organism that is a historical remnant of a structure that served a function in the organism's ancestors

homologous

structures in different species that are similar because of common ancestry

convergent

the evolution of similar features in independent evolutionary lineages

phylogenetic tree

a branching diagram that reflects a hypothesis about evolutionary relationships among groups of organisms

microevolution

evolutionary change below the species level; change in allele frequencies in a population over generations

analogous

having characteristics that are similar because of convergent evolution not homology

population

a group of individuals of the same species that live in that same area and interbreed, producing fertile offspring

cline

a graded change in a character along a geographic axis

Hardy-Weinberg

the principle that frequencies of alleles in a population remain constant from generation to generation, provided that only segregation and recombination of alleles are at work

gene pool

all copies of every type of allele in every individual in a population.

founder effect

genetic drift when a few individuals become isolated from a larger population and form a new population not reflective of that of the original population.

genetic drift

chance events cause unpredictable fluctuations in allele frequencies from one generation to the next. Effects are most pronounced in small populations.

gene flow

the transfer of alleles from one population to another, resulting from the movement of fertile individuals or their gametes

bottleneck effect

genetic drift when the size of a population is reduced, as by a natural disaster or human actions and surviving population is not reflective of that of the original population.

macroevolution

evolutionary change resulting in the formation of new species

speciation

an evolutionary process in which one species splits into two or more species

reproductive isolation

the existence of biological factors that (barriers) that impede members of two species from producing viable, fertile offspring.

species

a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring.

stability factor

random interbreeding, mitosis, lack of selection, genetic drift, migration

punctuated equilibrium

long periods in which a species undergoes little or no morphological change, interrupted by brief periods of sudden change.

change factor

mutation, cross overs, independent assortment, fertilization

fossil

a preserved remnant or impression of an organism that lived in the past