evolution

what is artificial selection?

• selection by humans for breeding of useful traits from the natural variation among different organisms

• the process by which organisms with beneficial adaptations survive and leave more offspring because they are better suited for the environment

• struggle for survival

• changes across generations

what is natural selection?

• physical differences in biological structures

• differences in patterns of activity in response to the environment

• changes in an organism’s metabolic process

• by which organisms with beneficial adaptations survive and leave more offspring because they are better suited for their environment

what is evolution?

• smallest unit of time on the scale

• largest division of geological time

• changes described over time

• changes that occur within a population between one generation and the next

what are structural adaptations?

• physical differences in biological structure

• a species that blends in with the environment

• a species that copies another species

• changes in an organism’s metabolic processes

what are homologous structures?

• scientists who study fossils

• features that are similar in structure but appear in different organisms and have different functions

• structures that perform similar functions but are not similar in origin

• shows the evolutionary history for a group of species

what is genetic variation?

• increases the population’s chance of survival for some individuals

• combined alleles of all individuals in a population

• random change in the DNA of a gene

• new allele combinations

what is directional selection?

• when both extreme phenotypes are favored

• the movement of alleles between populations

• when phenotypes at one extreme of a trait’s range are favored

• when an intermediate phenotype is favored and becomes more common in a population

what is the bottleneck effect?

• genetic drift that occurs after an event greatly reduces the size of a population as well as genetic variation

• genetic drift that occurs when a small group breaks away from a larger population to colonize new territory

• physical barriers dividing a population into two or more groups

• barriers that involve timing

what is the founder effect

• evolution towards similar characteristics in distantly related species

• occurs when certain traits increase mating success

• closely related species evolving in different directions to become increasingly different

• genetic drift that occurs when a small group breaks away from a larger population to colonize new territory

what is gradualism?

• when two or more species evolve in response to changes in each other

• evolutionary changes that occur over long periods of time

• bursts of evolutionary activity that are followed by long periods of stability

• organisms that rapidly move into the area to fill empty niches