105929
Description
Flashcards by Alice Burke, updated more than 1 year ago
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Created by Alice Burke
about 11 years ago
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| Question | Answer |
| Population Differentiation | different phylogenetic types in different geo. regions. Pops. don't always mix so they have the opportunity to diverge. |
| Variation between population | If populations are in diff. geo. regions, pops. aren't always the same due to gene flow and drift. Variation can also exist between indivs. of the same pop. |
| Variation between population | If populations are in diff. geo. regions, pops. aren't always the same due to gene flow and drift. Variation can also exist between indivs. of the same pop. |
| Non-Panmictic Populations | Indivs. of a spp may be subdivided into spatially distinct pops that differ from one another. Mating can occur @ random within each pop. but not between them. |
| Panmictic Populations | If a pop. is panmictic, there are NO mating restrictions (behavioural or genetic) and ALL indivs. are potential partners. There must be potential for mixing and producing fertile viable offspring. |
| Genetic Exchange Between Populations | Genetic exchange is mediated by the movement of indivs. NS & drift determine how much of a contribution the migrating indiv. makes to the gene pool. So it is not the indivs. ability to move by but their success when they get there. REMEMBER this is probably FD - the rarer you are, the more successful you are. |
| F-stats | Used to model the genetic exchange between populations. They are an estimate of GENETIC SUBDIVISION and can be translated in to the number of migrants - but they aren't very good. F-stats estimate how different/subdivided the population is overall. |
| Metapopulations | A series of subdivided pops connected by different migration rates. Individually the pops. are unstable (often due to heavy fragmentation) and extinction risk is high. They rely on neighbouring local pops. to recolonise them after extinctiom - RESCUE EFFECT. As a whole the metapopulation is stable. |
| Metapopulations & Hardy Weinberg | Indiv. pops. may NOT be in the HW equilibrium or they may be... But in the structured metapopulation there may still be fewer heterozygotes than expected. This is the WAHLUND EFFECT |
| Genetic Types & Population Structure | Genetic types can be used to infer pop. structure. But if we are using samples as indicators, they are telling us the level of subdivision so that are TRUE indicators. This makes it difficult to distinguish between the true heterozygote defecit & apparent heterozygote if we don't known the true pop. structure. |
| Heterozygote Defecit | This can show differences in pops. and can be considered a form of inbreeding. If there's no gene flow, then the alleles don't get mixed up as much - lack of recombination. So there is a decline in genetic variation = more prone to extinction. |
| Genetic Exchange & Selection | The amount of genetic information exchanged depends on the strength of selection. If there is no selection then migration is a very strong force for equalising allele frequency (HARDY WEINBERG). If there IS selection, genetic differences can still be maintained despite migration |
| Effective Population Size | Ne: No. of indivs. contributing to the next generation. It is based on reproductive success and is ALWAYS lower than the actual population size (N). It is influenced by population size & structure, unequal sex ratios, variance in repro. success & population subdivision. |
| Genetic Exchange & Endosymbionts | Genetic exchange can be influenced by bacterial endosymbionts. Maternally inherited endo. can alter the biology of their host to favour their own transmission. They can also reduce the success of offspring if parents don't carry the same bacterial strain. Wolbachia in spiders & Rickettsia in butterflies. Sways sex ratio to females. |
| Selective Sweeps | Bacteria manipulate their hosts to become the most successful. Because loci are not always innherited independently, other things can get 'swept' along too with the selection driver - GENETIC HITCH-HIKING. E.g if Wolbachia is increasing repro. success and the trait for red legs is on the same gene locus, this may get swept to high freq. too. |
| Phylogeography | Geo. distribution of genetic variants that reflects past events - primarily this is colonisation history. They often tell us about processes that have affected more than 1 spp. E.g. the 3 likely migration routes taken by Euro spp after the last glacial event. Phylogeo. analysis requires the evolutionary history to be known for the different genetic variants. |
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