unit 8- natural selection (14&15) Flashcards
evolution
a change in gene frequency over time
change of organisms over time
adaptation
trait shaped by natural selection that increases an organism’s reproductive success in a particular environment
descent with modification
identified hat species on earth today descended from ancestral species
natural selection
“survival of the fittest”
process where individuals that are best fit for their environment survive to reproduce
(the change in groups of organisms through time)
how old is the earth
4.5 billion years old
4 basics of natural selection
- individuals show a variety of genes
- variations pass from parent to offspring
- more offspring are produced than the environment can support
- variations that increase reproductive success will be more likely to be passed on
darwin
collected specimens and observed finches to develop two main points- descent with modification & natural selection
artificial selection
the selective breeding of domesticated plants and animals to produce offspring with genetic traits that human value
(Ex.dogs)
fossil record
chronological collection of life’s remains in the rock layer (old on bottom, new on top)
three parts of comparative anatomy
- homologous structures
- analogous structures
- vestigial structures
homologous structures
similar structures inherited by a common ancestor
Ex. arms/ wings
analogous structures
structures used for the same purpose and have similar features but aren’t inherited from the same ancestor
(Ex. wings- needed to fly but evolved separately)
vestigial structures
structures that are reduced forms of functional structures in organisms
(things that don’t really work anymore)
(Ex. human appendix)
bottleneck
when a population declines to a very low number
founders effect
small amount of organisms from a population become isolated from other populations. those traits are passed along which can lead to a change in frequency
genetic drift
any change in the allele frequencies in a population that is due to chance
types of genetic drift
founders effect and bottleneck
reproductive isolation
prevents gene flow among populations
types of reproductive isolation
prezygotic & postzygotic isolation
geographic isolation
a physical barrier dividing two or more populations
adaptive radiation
(divergent evolution) diversification of a species into a number of different species in a relatively short period of time
(follows mass extinction)
biological fitness
measure of the relative contribution an individual trait makes to the next generation
(measurement of how many can reproduce)
population
a group of individuals of the same species living in the same area at the same time
variation
the differences among members of the same species
