Evolution Questions #3 Speciation

Does natural selection produce new species? No, it changes allele frequencies in populations, does not produce a new species

What is speciation? the process of a single species changing into two or more new species whose members interbreed and produce fertile offspring

What is reproductive isolation? when a population splits into two groups that no longer interbreed and eventually evolve into two separate species

What is the importance of reproductive isolation in evolution? it is the ultimate cause of speciation, the diversity of species

What are 3 ways that reproductive isolation leads to speciation? geographic isolation, behavioral isolation, and temporal isolation

What is geographic isolation? when a population is split into two or more geographically isolated subdivisions; organisms cannot bridge barriers, such as mountains or bodies of water and populations no longer interbreed

What is behavioral isolation? when two populations that are capable of interbreeding develop differences in courtship rituals or other behaviors

What is temporal isolation? when two or more species reproduce at different times

What are the 2 types of extinction What are the 2 types of extinction? Which has a greater impact on evolution? Why? mass extinction and background extinction; mass extinctions shape the overall pattern of evolution because of dramatic changes

Describe background extinction. species becoming extinct because of the slow but steady process of natural selection

Describe mass extinction. the death of one or more species in a relatively short time, usually as a result of environmental change or an environmental disaster -entire ecosystems vanish and food webs collapse -natural selection can’t compensate quickly enough - biodiversity dramatically reduced - empty niches =new opportunities for survivors -recovery typically between 5 and 10 million years

What is gradualism? a slow, steady change in a particular line of descent; the fossil record is proof that many organisms changed gradually over time

What is punctuated equilibrium? equilibrium that is interrupted by brief periods of more rapid change; the fossil record also reveals periods of relatively rapid change in many groups of organisms; most new species seem to be produced during periods of rapid change

What is equilibrium? How does evolution proceed after states of equilibrium? when organisms do not change much over a long stretch of time; rapid evolution occurs after a small population becomes isolated or migrates from the main population, evolving faster than the larger one because genetic changes spread more quickly among fewer individuals

What are 3 patterns of evolution? adaptive radiation, convergent evolution, and coevolution

What is adaptive radiation? an evolutionary process by which a single species or a small group of species evolves over a relatively short time into several different forms that live in different ways; caused by migration, extinctions, or when a species evolves a new feature that enables it to take advantage of a previously unused environment

What is an adaptive zone? a set of ecological niches that may be occupied by a group of species that exploit the same resources in a similar manner; new adaptations allows a group to exploit a new adaptive zone Ex. birds and flight

What is convergent evolution? evolution that occurs as a result of adaptations to living in similar environments; species with different ancestors evolve to look similar due to similar selection pressures; natural selection can mold different body structures to perform similar functions Ex> analogous structures (wings on birds & insects)

What is coevolution? process by which two species evolve in response to changes in each other over time; in time neither organism can survive without the other; an evolutionary change in one organism is usually followed by a change in the other