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Bio2Ch24
| Question | Answer |
|---|---|
| Study of genes and genotypes in a population | Population genetics |
| Population genetics helps us understand how genetic variation is related to _____ variation | Phenotypic |
| All of the alleles for every gene in a given population | Gene pool |
| In a gene pool, emphasis is often on _____ in alleles between members of a population | Variation |
| Group of individuals of the same species that occupy the same environment and can interbreed with one another | Population |
| Many traits display variation within a population | Polymorphism |
| Due to two or more alleles that influence phenotype | Polymorphism |
| Two or more alleles | Polymorphic gene |
| Predominantly single allele | Monomorphic gene |
| Smallest type of genetic change in a gene; most common - 90% of variation in human gene sequences | Single nucleotide polymorphism (SNPs) |
| Large, healthy populations exhibit a high level of _____ diversity | Genetic |
| What are the conditions for Hardy-Weinberg equilibrium? | No new mutations, no natural selection, large population, no migration, random mating |
| Changes in a population's gene pool from generation to generation | Microevolution |
| Microevolution occurs because... | New genetic variation (mutations), evolutionary mechanisms that alter the prevalence of allele or genotype (natural selection) |
| Process in which beneficial traits that are heritable become more common in successive generations | Natural selection |
| Over time, natural selection results in _____ | Adaptations |
| Likelihood of an individual contributing fertile offspring to the next generation | Reproductive success |
| Reproductive success is attributed to what two categories of traits? | Traits that make organisms better adapted to environment (more likely to survive to reproductive age), traits directly associated with reproduction (produce viable offspring) |
| Relative likelihood that a genotype will contribute to the gene pool of the next generation as compared with other genotypes | Fitness |
| Fitness is a measure of _____ success | Reproductive |
| Average reproductive success of members of a population | Mean fitness of population |
| As individuals with higher fitness values become more prevalent, natural selection _____ the mean fitness of the population | Increases |
| Individuals at one extreme of a phenotypic range have greater reproductive success in a particular environment | Directional selection |
| What are the initiators of directional selection? | New allele with higher fitness introduced (by mutation), prolonged environmental change |
| Directional selection may eventually lead to a _____ gene | Monomorphic |
| Favors the survival of individuals with intermediate phenotypes | Stabilizing selection |
| Stabilizing selection tends to _____ genetic diversity | Decrease |
| Extreme values of a trait are selected against (such as clutch size in birds; too many eggs and offspring die due to lack of care/food, too few eggs doesn't contribute enough to next generation) | Stabilizing selection |
| Favors the survival of two or more different genotypes that produce different phenotypes | Disruptive/diversifying selection |
| Disruptive/diversifying selection is likely to occur in populations that occupy _____ environments | Heterogeneous |
| In disruptive/diversifying selection, members of the populations can freely _____ | Interbreed |
| Balancing selection maintains _____ diversity | Genetic |
| Two or more alleles are kept in balance, and therefore are maintained in a population over the course of many generation | Balanced polymorphism |
| What are the two common ways in which balancing selection occurs? | Heterozygote favored, negative frequency-dependent selection (rare individuals have a higher fitness) |
| Prey that exhibits a rare polymorphism that affects its appearance is less likely to be recognized by the predator (different color, etc.) | Negative frequency-dependent selection |
| Sexual selection is a form of _____ selection | Natural |
| Directed at certain traits of sexually reproducing species that make it more likely for individuals to find or choose a mate and/or engage in successful mating | Sexual selection |
| In many species, affects male characteristics more intensely than it does female | Sexual selection |
| Between members of the same sex (horns in male sheep, antlers in male moose, male fiddler crabs with enlarged claws) | Intrasexual selection |
| Males directly compete for mating opportunities or territories | Intrasexual selection |
| Between members of the opposite sex; often results in showy characteristics for males (peacock) | Intersexual selection |
| Intersexual selection is also known as _____ choice | Mate |
| In intersexual selection: genital tract or egg selects against genetically related sperm (inhibits interbreeding) | Cryptic female choice |
| Changes allelic frequency due to random chance | Genetic drift |
| Genetic drift is due to random events unrelated to _____ | Fitness |
| Favors either the loss or fixation of an allele (frequency reaches 0% or 100%); common in small populations | Genetic drift |
| Population reduced dramatically and then rebuilds | Bottleneck |
| Disaster eliminated members without regard to genotype | Bottleneck |
| Surviving members may have allele frequencies different from original population; allele frequencies can drift substantially when the population is small | Bottleneck |
| After a bottleneck, the population in question will likely have _____ genetic variation | Less |
| Small group of individuals separates from a larger population and establishes a new colony | Founder effect |
| Relatively small founding population is expected to have _____ genetic variation than original population | Less |
| Much of the variation seen in natural populations is cased by genetic drift; does not preferentially select for any particular allele | Neutral variation |
| Most genetic variation is due to the accumulation of _____ mutations that have attained high frequencies due to genetic drift | Neutral |
| Neutral mutations don't affect the _____ so they are not acted upon by natural selection | Phenotype |
| Much of the modern variation in gene sequences is explained by _____ variation rather than adaptive variation | Neutral |
| Nucleotide substitutions are much more likely in the _____ base of a codon (usually doesn't change the amino acid) | Third |
| Changing the _____ _____ is usually harmful to the coded protein | Amino acid |
| Gene flow occurs when individuals migrate between populations having different allele frequencies | Migration |
| Tends to reduce differences in allele frequencies between two populations | Migration |
| Migration tends to _____ genetic diversity within a population | Increase |
| Individuals choose their mates regardless of their genotype and phenotype | Random mating |
| Individuals with similar phenotypes are more likely to mate | Assortative mating |
| Increases the proportion of homozygotes | Assortative mating |
| Dissimilar phenotypes mate preferentially | Disassortative mating |
| Favors heterozygosity | Disassortative mating |
| Choice of mate based on genetic history; does not favor any particular allele but it does increase the likelihood that the individual will be homozygous | Inbreeding |
| May have negative consequences with regard to recessive alleles | Inbreeding |
| Lower mean fitness of a population if homozygous offspring have a lower fitness value | Inbreeding |
Created by:
stephanielynhannigan