unit 7 part 1 (7.1-7.5) Flashcards
evolution
change in the genetic makeup of a population over time
natural selection
process that organisms, having adaptions suited for a particular environment, have a greater chance of survival and reproduction, passing the adaptations to subsequent generations
competition
organisms struggle with other organisms to get limited resources like space, food, mates, nutrients, light
variation
genetic differences among organisms (mutations and sexual reproduction increase variation)
adaptations
traits that provide an advantage in a particular environment, increase chances of survival and reproduction
fitness
ability of an organism to survive and produce offspring
reproductive success
production of offspring
heritability
ability to pass on adaptations to successive generations
what contributes to fitness?
heritability and reproductive success
biotic vs abiotic
biotic is living things and abiotic is nonliving components
populations are less likely to evolve in a __ environment
stable
use and disuse
parts of the body that are used frequently become larger and stronger while others deteriorate
descent with modification
unity of life is attributed to decent of all organisms from one ancestor that had modifications along the way
artificial selection
humans modify other species by selectively breeding individuals for desired traits (dog breeding)
key thing rizz wanted us to know
individuals do not evolve, populations evolve over time
homology
similar characteristics that function differently
vestigal structures
remains of features that served a function in the organism’s ancestors.
convergent evolution
similar environmental conditions can select for similar traits in different populations or different species over time
genetic variation
describes genotypic and phenotypic differences between individuals in a population
selective pressure
any biotic or abiotic factors influencing survivability
analougous structure
similar traits observedin distantly related or unrelated species
darwins two observations
1) variations (same pop, diff traits)
2) more offspring than environment can support (everyone is fighting for survival because stuff is limited)
darwins two inferences
1) survived have offspring, differential reproductive success
2) individual organisms do not evolve, adaptations are passe down
order of natural selection
mutations -> variations -> selective pressure -> change in population
mutations
contributes to changes in genetic makeup, creates genetic variation, provides new phenotypes to contribute to evolution
genetic drift
chance events that cause allele frequencies to fluctuate unpredictibally from one generation to the next (especially in small populations)
founder effect
few individuals become isolated from a larger population, the smaller group may establish a new population with a gene pool that differs from the source (ex: blown away by storm)
bottleneck effect
sudden change in environment (fire, flood, etc) that dramatically reduces size of a population (by chance certain allels can over represent themselves)
gene flow
transfer of alleles into or out of a population due to movement of fertile individuals or their gametes (ex: insects carrying pollen)
relative fitness
contribution an individual makes to the gene pool of the next generation RELATIVE to the contributions of other individuals
directional selection
occurs when conditions favor individuals at one extreme of the phenotypic range (shifts in pop frq curve in one direction, common when environment changes or migtation)
disruptive selection
occurs when conditions favor individuals at both extremes of phenotypic range over intermediate phenotypes
stabilizing selection
acts against both extremes an favors intermediate varients, reduces variation and maintains status quo of particular phenotypic character
rapid repro =
increased mistakes!
population
group of individuals of the same species that live in the same area and produce offspring (breed with eachother)
gene pool
all copies of every type of allele in all members of the population, the deck of genes that is being continiously reshuffled
hardy weinberg principal
helps us conclude whether population is evolving
hardy weinberg equalibrium
frq of alleles and genotypes in a population will remain constant from gen to gen, if ONLY mendelian segregation and recominant alleles are at work
5 conditions necessary for hardy equilibrium
1) large population (no genetic drift)
2) absence of migration (no gene flow)
3) no net mutation
4) random mating (no sexual selection)
5) absence of natural selection
5 causes of allele frequency changes
1) population shrink
2) mating (nonrandom)
3) mutation
4) movement (migration)
5) natural selection
