CAMPBELL-BIOLOGY-IN-FOCUS CHAPTERS 24 EXAM Q’S AND A’S

CAMPBELL-BIOLOGY-IN-FOCUS CHAPTERS 24 EXAM Q’S AND A’S speciation - answer- the process by which one species splits into two or more species microevolution - answer- changes over time in allele frequencies in a population macroevolution - answer- the broad pattern of evolution above the species level species - answer- a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring - but do not produce viable, fertile offspring with members of other such groups gene flow - answer- the transfer of alleles between populations reproductive isolation - answer- the existence of biological factors that impede members of two species from interbreeding and producing viable, fertile offspring hybrids - answer- offspring that result from an interspecific mating prezygotic barriers - answer- before the zygote; block fertilization from occurring postzygotic barriers - answer- After a sperm cell from one species overcomes prezygotic barriers and fertilizes an ovum of another species, ______ may contribute to reproductive isolation after the hybrid zygote is formed Prezygotic Barrier examples pre mating - answer- Habitat isolation temporal isolation behavior isolation Prezygotic barrier exemples mating attempted - answer- mechanical isolation gametic isolation Postzygotic barrier examples - answer- reduced hybrid viability reduced hybrid fertility hybrid breakdown Habitat isolation - answer- two species that occupy different habitats within the same area may encounter each other rare, if at all, even though they are not isolated by obvious physical barriers such as mountain ranges ex: water snake vs. land snake Temporal isolation - answer- species that breed during different times of the day, different seasons, or different years cannot mix their gametes ex: skunk mating in summer vs skunk mating in winter behavioral isolation - answer- courtship rituals that attract mates and other behaviors unique to a species are effective reproduction barriers, even between closet related species. such behavioral rituals enable MATE RECOGNITION - a way to identify potential mates of the same species ex: blue footed birds only attract other blue footed birds mechanical isolation - answer- mating is attempted, but morphological differences prevent its successful completion ex: snails with genital openings that are not aligned with each other gametic isolation - answer- sperm of one species may not be able to fertilize the eggs of another species. for instance, sperm may not be able to survive in the reproductive tract of females of the other species, or biochemical mechanisms may prevent the sperm from penetrating the membrane surrounding the other species' eggs ex: sea urchins ocean infused sperm not mixing with other urchins n stuff reduced hybrid viability - answer- the genes of different parent species may interact in ways that impair the hybrid's development or survival in its environment ex: salamander not completely developed reduced hybrid fertility - answer- even if hybrids are vigorous, they may be sterile. if the chromosomes of the two parent species differ in number or structure, meiosis in the hybrids may fail to produce normal gametes. since the infertile hybrids cannot produce offspring when they mate with either parent species, genes cannot flow freely between the species ex: male donkey and a female horse mate to make a mule, but the mule is sterile hybrid breakdown - answer- some first generation hybrids are viable and fertile, but when they ate with another or with either parent species, offspring of the next generation are feeble or sterile ex: rice can have one generation of god offspring, but then after they become separated by postzygotic barriers biological species concept - answer- Definition of a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are not able to produce viable, fertile offspring with members of other populations emphasizes the separateness of species from one another due to reproductive barriers morphological species concept - answer- characterizes a species by body shape and other structural features; can be applied to asexual and sexual organisms and it can be useful even without information on the extent of gene flow ecological species concept - answer- views a species in terms of its ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment emphasizes the role of disruptive natural selection as organism adapt to different environmental conditions