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CH 16 Evolution

CP biology evolution test 2

QuestionAnswer
What causes genes to vary? mutation, environmental factors, recombination of alleles during sexual reproduction, and the random pairing of a sperm and an egg
what is a gene pool? the total amount of genetic information available in a population
what is gene flow? the process of genes moving from one population to another
what is immigration? individuals moving into a population
what is emigration? individuals moving out of a population
what is genetic drift? when allele frequencies in a population change due to a chance event.
What kind of populations are most affected by genetic drift? small populations
what is an example of genetic drift? The buffalo almost went extinct due to humans hunting them. The population had to grow back from a very small gene pool thus there is not much diversity left in the buffalo populations
what is bad for a population to have little genetic diversity? they are at risk for extinction because a disease could affect the entire population the same way and wipe the whole population out.
what is non random mating? when organisms choose their mates based on desired characteristics
what is sexual selection? the same thing as non random mating- when organisms choose their mates based on desired characteristics
Why are brightly colored males attractive female birds? brightly colored feathers indicates the male is healthy and has good "fitness"
what is another phrase for natural selection? survival of the fittest
what is stabilizing selection? when the center of the bell curve is favored
give an example of stabilizing selection... intermediate lizard size is favored because when lizards are too small they are slow and get eaten easily and when they are too big they are spotted and eaten easily.
what is disruptive selection? when the extremes of a bell curve are favored
give an example of disruptive selection... Say the environment is both black and white. Organisms with white (one end of the bell curve) blend in and so do black (other end of the bell curve). The intermediate gray colored individuals are spotted easily and become prey.
what is directional selection? when one extreme of a bell curve is favored
give an example of directional selection? ant eaters have long tongues to reach into ant nests. If ants keep building their nests deeper then ant eaters will evolve over time to have longer tongues (one side of the bell curve is favored)
what is speciation? the process of how species form
what is morphology? studying internal and external features of an individual to determine which species it is in.
what is morphology evidence sometimes misleading? sometimes two organisms in the same species look very different... but they can still interbreed so they are still the same species.
what is geographic isolation? when members of a species are physically separated because their habitat becomes divided
what is an example of geographic isolation? Death Valley used to be covered by water. After thousands of years the land dried up and only a few pools of water remained. Fish populations living in lake were separated into smaller groups which eventually became different species.
what is allopatric speciation? when a new species forms due to geographic isolation
give an example of allopatric speciation Before the grand canyon was divided by the colorado river there was one species of squirrel. After the river cut through the canyon the squirrels were separated and after many years the two groups became two different species
what is reproductive isolation when barriers present successful breeding
what is pre reproductive isolation when barriers prevent successful breeding before fertilization
what is an example of pre reproductive isolation? a mating call is not recognized, organisms mate during different seasons, genitals are not compatible.
what is post reproductive isolation? when barriers prevent successful breeding after fertilization
what is an example of post reproductiveisolation? offspring don't develop fully, die early, or the offspring produced are not fertile and thus can't make more of themselves
what is sympatric speciation? when a group within the same geographic area become different species
what is an example of sympatric speciation? a population of insects live on a single type of plant. If by chance some begin to live on another plant they might no longer interbreed with the others and eventually become a different population.
what is punctuated equilibrium? a model that shows that evolution happens in bursts followed by long periods of slow/no evolution
what is gradualism? a model that shows that evolution occurs gradually all the time.
which model is better punctuated equilibrium or gradualism? there is evidence that supports both models
Created by: ruth.baker