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Bio 152 Test 1 Part2
Chapter 23
| Question | Answer |
|---|---|
| A change in allele frequencies in a population over generations | Microevolution |
| Varying forms of a gene | Alleles |
| When the medium ground finch's bird population dropped and the remaining birds had large beaks and this species evolved (directional selection) is an example of _____ | microevolution |
| What processes produce the variation in gene pools that contributes to differences among individuals | Mutation and sexual reproduction |
| Underlying genetic makeup | Genotype |
| What it looks like | Phenotype |
| Characters that contribute to variation within a population and can be classified on an either-or basis | Discrete characters |
| Characters that contribute to variation within a population and vary along a continuum within a population | Quantitative characters (much more common, an example is metabolic rate) |
| The many different forms, shapes and varieties in a population | Polymorphisms |
| Measures the average percent of loci that are heterozygous in a population | Average heterozygosity |
| Differences between gene pools of separate populations or population subgroups | Geographic variation |
| A graded change in a trait along a geographic axis (environmental gradient) | Cline |
| Changes in the nucleotide sequence of DNA, cause new genes and alleles to arise | Mutations |
| Only mutations in cells that produce ____ can be passed to offspring | Gametes, somatic cells are not passed to offspring |
| A change in one base in a gene (a single change in one letter) ex. sickle cell | Point mutation |
| A localized group of individuals capable of interbreeding and producing fertile offspring | Population |
| Consists of all the alleles for all loci in a population | Gene pool |
| Place on a chromosome where the gene is located | Locus |
| Describes a population that is not evolving | Hardy-Weinberg principle |
| States that frequencies of alleles and genotypes in a population remain constant from generation to generation | Hardy-Weinberg principle |
| Describes the constant frequency of alleles in such a gene pool | Hardy-weinberg equilibrium |
| Five conditions for non-evolving populations | No mutations, random mating, no natural selection, extremely large population size, no gene flow |
| Three major factors that alter allele frequencies and bring about most evolutionary change | Natural selection, genetic drift, gene flow |
| Describes how allele frequencies fluctuate unpredictable from one generation to the next; tends to reduce genetic variation through losses of alleles; only important in small populations | Genetic drift |
| Unexplained fluctuations resulting in complete lack of recessive alleles in flower generations is an example of ____ | Genetic drift |
| Occurs when a few individuals become isolated from a larger population; allele frequencies in the small founder population can be different from those in the larger parent population | Founder effect |
| Individuals blown from mainland to an island who then found a new population is an example of ________ | the founder effect |
| Asudden reduction on population size due to a change in the environment. The resulting gene pool may no longer be reflective of the origin and if the population remains small it may be further affected by genetic drift | Bottleneck effect |
| A severe reduction of greater prarie chickens with a low hatch rate and an avg. number of 5.2 alleles for each gene is an example of _____ | the bottleneck effect/genetic drift |
| Effects of genetic drift | Significant in small populations, causes allele frequencies to change at random, can lead to a loss of genetic variation within populations, can cause harmful alleles to become fixed |
| Consists of the movement of alleles among populations, tends to reduce difference between populations over time | Gene flow |
| Can increase the fitness of a population | Gene flow |
| The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals | Relative fitness |
| Three modes of natural selection | Directional, disruptive, and stabilizing |
| Favors individuals at one end of the phenotypic range | Directional selection |
| Favors individuals at both extremes of the phenotypic range | Disruptive selection |
| Favors intermediate variants and acts against extreme phenotypes | Stabilizing selection |
| Example of stabilizing selection | Newborn babies in human population, selection for babies 6-8 pounds |
| Example of directional selection | European black bears became bigger during ice age |
| Example of disruptive selection | Black-bellied seedcracker finches in Cameroon. Small-billed birds eat soft seeds and large-billed birds crack hard seeds |
| Increases frequencies of alleles that enhance survival and reproduction | Natural selection |
| Natural selection for mating success | Sexual selection |
| Marked difference between the sexes in secondary sexual characteristics (males or females looking or behaving differently) | Sexual dimorphism |
| Example of sexual dimorphism and sexual selection | Peacocks |
| Competition among individuals of one sex (often males) for mates of the opposite sex- think within | Intrasexual selection |
| Often called mate choice. Occurs when individuals of one sex (usually females) are choosy in selecting their mates-think between | Intersexual selection |
| Example of intra and intersexual selection | Bower birds building structures and females choosing |
| Example of frequency-dependent selection | Scale-eating fish left-mouthed or right-mouthed |
| Why natural selection cannot fashion perfect organisms | Selection can act only on existing variations, evolution is limited by historical constraints, adaptations are often compromises, chance, natural selection, and the environment interact |
Created by:
AliRutherford
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