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Evolution exam
| Term | Definition |
|---|---|
| phenotypic plasticity | An organism that develops different phenotypes for the same genotype in different environments. This is Non-inherited, Non-genetic variation |
| How do new alleles arise? | (single nucleotide changes) and indels (insertions/deletions) Can be spontaneous (replication errors) or induced (UV radiation, mutagens) . |
| How do new genes arise? | unequal crossing over and retrotransposition |
| Unequal crossing over | during meiosis, homologous chromosomes misalign, producing a duplication in one chromatid and a deletion in the other. |
| Retroposition | mRNA is reverse-transcribed and inserted into DNA; new copy lacks introns and promoters . |
| polygenic trait | trait controlled by two or more genes |
| How do new polygenic traits arise? | Chromosomal inversions supress recombination, creates linked "supergenes" |
| How Do New Anatomical Structures Arise? | Through Changes in Developmental Regulatory Genes, usually Homeobox (HOX) genes |
| Homeotic Mutants | individuals where mutations in Hox genes (or their regulation) cause one body part to develop in the place of another. |
| Polyploidy | condition in which an organism has extra sets of chromosomes |
| Aneuploidy | A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number. |
| Euploidy | the correct number of chromosomes in a species |
| What is the Adaptive Value of Sex? | Sex allows organisms to vary and adapt to gradual environmental change that occurs over time. |
| Cost of sex | Finding a mate (exposure) • Competing for a mate • Copulation complications • Diseases |
| Red queen theory | evolutionary hypothesis that states organisms must constantly adapt, evolve, and proliferate not just for reproductive advantage but also to survive while competing with ever-evolving opposing organisms. |
| Linkage Equilibrium | Two genes are said to be in linkage equilibrium when the combination of their alleles in individuals is random — i.e., the allele at one locus does not predict the allele at another locus |
| Linkage Disequilibrium | occurs when alleles at different loci are not associated randomly — that is, certain allele combinations occur together more (or less) often than expected by chance. |
| impact of sex on Linkage Disequilibrium | Sex reduces disequilibrium, however, in a random-mating population, linkage disequilibrium can be created by selection genotypes, genetic drift, and population admixture. |
| The only known long-term asexual Eukaryote group | Rotifera: Class Bdelloidea |
| parental investment: | energy spent constructing/caring for offspring. higher for females. |
| Female selective behavior. | Females have expensive gametes. Their reproduction is limited by resources. This leads them to be more selective over the mates they choose. |
| Male competitive behavior. | males have cheap gametes. Reproduction limited by access to mates. this leads them to be competitive for mates. |
| intersexual selection: | Selection whereby individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex; also called mate choice. |
| intrasexual selection | A direct competition among individuals of one sex (usually the males in vertebrates) for mates of the opposite sex. |
| Sexual Selection and Genetic Correlations | If their is variation in male traits and variation in female preference, and these are heritable, there will be a genetic correlation between trait and preference alleles. this is non-random mating and it causes (= linkage disequilibrium) |
| Models of Mate Choice: Good Genes | Trait preferred by females is an honest indicator of overall male genetic quality. Females chose based on frog call length. evidence shows frogs with longer call length has better genes. |
| Models of Mate Choice: Sensory Bias | Female preferences are based on their own inherent eco-physiological bias; may or may not indicate overall male genetic quality. |
| Models of Mate Choice: Resource-Based | Females prefer males based on an extended phenotype; may or may not indicate overall male genetic quality. this incudes, nests, gifts, stuff like that |
| extended phenotype | structures or behaviors constructed by organisms that can influence their fitness |
| Combat Intrasexual Selection | elephant seals; larger males monopolize harems. fight for the acsess to mate |
| Infanticide | an evolutionary adaptation resulting from strong intrasexual competition. baby killing. |
| intrasexual selection: sperm competition. | One male may produce fast 'sprinter'sperm as well as slow 'blocker' sperm that inhibit passage of sperm from other males. |
| hermaphrodites | often fight to be the male. |
| what is social behavior | The simplest possible social interaction involves two individuals: an actor and a recipient. A good outcome increasesA bad outcome decreases an individual's direct fitness. |
| four types of social behavior | Mutual benefit:both the actors benifit Selfishness:the actor benefits at the expense of the recipient. Altruism:the actor makes a sacrifice on behalf of the recipient Spite:the actor suffers a loss in order to impose a penalty on the recipient |
| Hamilton's rule | The principle that for natural selection to favor an altruistic act, the benefit to the recipient, devalued by the coefficient of relatedness, must exceed the cost to the altruist. |
| direct fitness | reproduction an individual achieves on its own |
| indirect fitness | additional reproduction by relatives that is made possible by the individual's actions |
| Kin Selection | natural selection leading to the spread of alleles that increase the indirect component of fitness |
| inclusive fitness | the sum of direct and indirect fitness |
| in order for altuism to evolve: | 1. individuals must be able to recognize each other 2. interactions among individuals are long term 3. retaliation in cases that individuals violate a 'pact' 1 |
| eusociality | highest degree of organization of socially living organisms, defined by: 1. reproductive division of labor 2. cooperative care of offspring 3. overlapping generations |
| haplodiploidy hypothesis | The relatively higher relatedness of full sisters in haplodiploid populations promotes altruism among siblings and consequently the evolution of eusociality. has been debunked |
| The Ecology and Life-History Hypothesis | evolution of eusociality due to other traits of a group and ecological context. eusiciality is a series of adaptations. Form groups Build defensible fortress Offspring do not disperse (inbreeding) Division of labor by inhibition Provisioning of larvae |
| fixed allele | all individuals are homozygotes for one allele |
| heterozygosity | the proportion of genotypes in a population that are heterozygous at a particular locus |
| migration | movement of alleles (individuals) from one population to another. Migration prevents populations from diverging / speciating. |
| outcrossing | mating among less related individuals. increases heterozygosity |
| inbreeding | mating among relatives. decreases heterozygosity |
| genetic drift | A change in the allele frequency of a population as a result of chance events rather than natural selection. |
| Four fates of Gene Duplicates: Overproduction | After duplication, both copies remain functional and produce the same protein. The organism benefits from higher expression levels or greater product quantity. |
| Four fates of Gene Duplicates: Dysfunction | The new gene becomes nonfunctional due to mutations. One duplicate loses function through accumulation of deleterious mutations, creating a pseudogene. |
| Four fates of Gene Duplicates: Diversification | The two copies partition the ancestral gene's functions or expression patterns; together they perform all ancestral roles. |
| Four fates of Gene Duplicates: Divergence | One copy acquires novel functions while the other preserves the ancestral one |
| fixed allele | all members of a population are homozygous for that allele |
| heterozygosity (H) | the proportion of genotypes in a population that are heterozygotes a measure of genetic variation in a population |
| Migration | movement of alleles (individuals) from one population to another. |
| impact of Migration | prevents populations from diverging / speciating because it prevents reproductive isolation and introduces new alleles, increasing heterozygosity |
| outcrossing | Involves crossing individuals of the same breed with less closely related individuals. increases heterozygosity |
| Inbreeding | mating among genetic relatives. increase the frequency of homozygotes. Inbreeding by itself does not change allele frequencies. Inbreeding changes genotype frequencies. |
| inbreeding depression | The negative reproductive consequences for a population associated with having a high frequency of homozygous individuals possessing harmful recessive alleles. |
| Inbreeding Coefficient (F) | = probability [paired alleles in a genotype are identical by descent] (a measure of tendency towards homozygosity) AND = proportion of H lost per generation due to mating among relatives |
| Loss of Heterozygosity due to Inbreeding | Hg+1 = Hg [1 - F] |
| Inbreeding avoidance adaptations: pre-copulatory | offspring dispersal mate choice and kin recognitios |
| Inbreeding avoidance adaptations: | post-copulatory • gamete recognition (like S-alleles) |
| sampling error | when the sample isn't representative of the whole |
| genetic drift | A change in the allele frequency of a population as a result of chance events rather than natural selection. |
| Neutral Theory | a mutant allele can arise within a population and reach fixation by chance, rather than by selective advantage. |
| Neutral alleles | Alleles that do not differ measurably in their effect on fitness. |
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