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UCSD BILD 3 MT1
Review of Midterm 1
| Question | Answer |
|---|---|
| inheritance of acquired characteristics | A belief that evo happened b/c properties of organisms acquired during lifetime & were somehow passed on to generations |
| natural selection | mech. for evo. A process favoring characteristics that inc. likelihood an org. will survive & selects against those that dec that likelihood. |
| Summary of Darwins Theory | species are mutable. nat. sel. can give rise to new adaptations & new species. nat & art sel. are sim. but not identical. variation must be heritable. evo is gradual and evo has no goal |
| Descent with modification | For evo to take place, the best adapted must be able to pass their characteristics onto next generation |
| exaptation | a pre-existing structure or behavior is co-opted to take up a new function (feathers) |
| Geologist James Hutton's suggestion of Earths geological history | deposition, folding, erosion, new deposition |
| sex linkage | a cond. in which a characteristic that apparently manifests more frequently in one sex is associated w/genes located in sex chromo. |
| genetic polymorphism | The existence together of many forms of DNA seq. at a locus w/in a population. |
| 2 parts of the Hardy Weinberg Law | allele freq. do not change in the absence of factors that can disturb them and if mating is random, genotype freq. at a locus can be predicted. |
| phenotypic polymorphism | Phenotypic polymorphism means that there are many different ways of expressing the same phenotype, or that the phenotype takes more than one form. ex. capea snail stripes. |
| Evolution simply consists of changes in allele frequency at polymorphic loci in populations | In order to understand evo. we need to ask how polymorphic alleles arose, how and why frequencies have changed and the consequences on the population. |
| mutation | heritable changes in genetic material |
| gene duplication | a second copy of a pre-existing gene is added to genome. ex. hemoglobin genes where various dupl'd hemogenes are turned off & on from embryo to fetus to adult. |
| retrotransposons | RNA seq. that can carry genes and insert copies into the genome |
| Darwinian fitness | number of viable offspring produced by an individual |
| transient polymorphism | last for a small number of generations before the allele that confers an advantage replaces the disadvantage one. |
| balanced polymorphism | natural selection maintains genetic polymorphism |
| heterozygote advantage | when the heterozygote at the locus has a higher w than either mutant or wildtype homozygote |
| trivial equilibrium | When one allele is lost and the other is fixed. Will not change until lost allele is reintroduced through mutation. |
| unconditional heterozygote adv. | advantage is present under all enviro cond. |
| founder effect | small number of founders by chance carry a mutant allele. they establish a new population whose gene pool is not reflective of the source population |
| gene flow | exchange of genes btwn populations or subpopulations of organisms |
| dispersal | organisms or their gametes are spread from one sub pop to other areas and may mix w/other sub pops. ex. plant pollen and gametes released by coral |
| Red Queen Race | When a species is confronted w/a continually cycling environment or cont. changing competitors, they must evolve to keep up w/changes. ex. snails and parasite in lake |
| sexual selection | selection for mating success |
| intrasexual | competition for among same sex for mates |
| intersexual | choices one sex makes in choosing competing members of the opp. sex |
| runaway selection | strong sexual selection characterized by extreme differences in appearance btwn sexes. |
| hybrid zones | regions of overlap btwn geo ranges of 2 species or genetically distinguishable sub pops in which hybridization btwn species or sub pops is taking place |
| sympatric speciation | species splits into 2 or more even though mbrs of the orig spec. move about freely w/in habitat and are capable of mating randonly w/one another. ex. mimulus, 2 pollinators:bees and hummingbird. enviro heterogeneity req. that has pot. impact on fitness |
| macro evolution | evo change resulting from the divergance of gene pools above the species level. |
| parsimonius tree | a phylogenetic tree in which the sum of the lengths of the branches is short. |
| morpho species | groups of organisms that show clear and consistent phenotypic differences |
| primary hybrid zone | form as a result of parapatric speciation |
| secondary hybrid zone | form when 2 species come together again after a period of allopatric speciation |
| parapatric speciation | speciation that can take place in adjacent sub pops even though there is still some gene flow btwn pools of the sub pops. |
| lumpers | taxonomists who do not think that slight morpho diff. are imp. and tend to lump similar ind. together into a single species |
| splitter taxonomists | put great weight on slight diff. in appearance and tend to split the same set of indiv. into different species or subspecies. |
| biological species/genetic species | a reproductive community of populations that occupies a particular eco niche in nature. |
| reproductive isolation | conditions (physio,beh, or geo) barriers that prevent potentially interbreeding pops from cross breeding |
| cryptic species | animals that appear identical but are genetically distinct |
| phylogenetic tree | tells about the evo history of organisms based on the assumption that present day org. can be traced back to a common ancestor |
| introgress | To infiltrate the genes of 1 species into the gene pool of another through repeated back crossing |
| isolating mechanisms | genetically based diff. btwn species that tend to prevent speciation |
| pre-zygotic mechanisms | physical & beh. diff btwn species or distinct groups w/in a pop that tend to prevent cross breeding. will be selected for if there is a disadv. to hybrids that lowers the fit. of the ind. that hybridize |
| behavioral isolation | a pre zyg. mech that prevents ind. from cross breeding based on behavioral diff such as mating rituals etc |
| ecological isolation | pre-zyg mech. isolation is due to different eco niches. ex.N.Amer. maggot fly has evolved several new species in the last 150yrs. shifted food pref. from fruit to apples, which were introduced by Euro colonists |
| temporal isolation | pre-zyg mech. 2 species become sexually mature at different times of yr. or mate at diff times of day. |
| loss of outbreeding | pre-zyg mech. when plants/animals lose capacity to cross, then hybrid zygotes never form and each of these selfing lineages is in theory capable of evolving into new species |
| hybrid sterility | post zyg. mech. A strong barrier to gene flow btwn species will be raised if hybrids survive and reach adulthood but turn out to be sterile. ex. mules |
| hybrid inviability | post zyg. mech when genetic incompatibilities leading to developmental problems, result in hybrid dying early in development. |
| reinforcement | selection for prezygotic mech. happens when likelihood that ind. will pick the wrong mate is decreased. no selection for post zygotic mech. |
| post zygotic mechanism | not selected for. Accumulate as a result of chance mutations, random drift, selective pressures unrelated to speciation process. slower to develope than pre-zygotic mech. |
| allopatric speciation | will occur when the env. is divided into geo. separate regions and organisms in the different regions diverge from their common ancestor. |
| linkage | tendency for 2 or more non-allelic genes to be inherited together b/c of close proximity on the same chromosome. |
Created by:
jriendea