chapter 22 themes of natural selection and evolution

lamarck: evolution of individuals

use and disuse theory (inheritance of acquired traits)

galápagos islands

islands species are similar to main land species (common ancestor)

descent with modification

all organisms share a common ancestor but species diverged over time

malthus’s essay

described limits on human population

artificial selection

human selection of desired traits in a species

observation 1 (natural selection)

organisms over reproduce

observation 2 (natural selection)

resources are limited

observation 3 (natural selection)

populations and resources remain stable

observation 4 (natural selection)

individuals in a population vary snowflakes

observation 5 (natural selection)

some of the variation is heritable

inference 1 (natural selection)

most individuals compete for limited resources

inference 2 (natural selection)

individuals with favorable inherited traits will likely reproduce

inference 3 (natural selection)

natural selection changes population characteristics over many generations

adaptation

traits possessed by an individual in a population that increases surviving, acquiring resources, and reproducing

the more generations the more individuals with adaptation?

differential reproductive success

fitness

organisms reproductive contribution to the next generation, inherited characteristics contribute to an organisms fitness

what is “best” is ever changing

populations biotic and abiotic are always changing, traits are eventually unused or favorable

for natural selection to happen…

there must be variation in the population, the variation results in differential reproductive success, the variation must be heritable

convergent evolution

the evolution of similar analogous features in distantly related groups

homologous

features with common ancestry but not similar function

analogous

features with similar function but not common ancestry