Mixing two populations without reproduction causes there to be a deficiency of heterozygotes.
This reduction in the number of heterozygotes is proportional to 2pqFST.
The two-locus Wahlund effect includes linkage disequilibrium.
FIS is the same as the simple inbreeding coefficient of a sub-population.
F-statistics can be defined by ANOVA models (see Weir and Cockerham )
The assumptions of the island model:
All populations are created equal, with N individuals and equal contributions to the migrant pool
There is NO spatial structure: in effect all populations are equally close to all other populations (no isolation by distance)
Everything is at equilibrium, nothing is changing.
Setting F'ST equal to FST:
when m is small.
* Even the island model is not always like the island model: statistical problems
* All populations are created equal, with N individuals and equal contributions to the migrant pool -
=> Population sizes are extremely variable, both in space and time
=> Populations are variable in their contributions to the migrant pool (e.g. sources and sinks)
=> populations vary through time in migration rates
=> populations fission and fuse
* There is NO spatial structure: in effect all populations are equally close to all other populations (no isolation by distance)
=> Dispersal is almost always distance related; there is isolation by distance
=> Dispersal is also often affected by other factors: rivers, roads, mountains, etc.
* Everything is at equilibrium, nothing is changing.
=> Populations often go extinct, and new ones form by colonization
=> History matters -- often the circumstances which determine the current population structure are the conditions of the past, which may have changed
=> There may be migration in from outside the study system, changing allele frequencies over time
* No selection
=> There's ALWAYS selection
* no mutation
=> Mutation can be at very fast rates, for example in microsatellites
* For mitochondrial markers (or others inherited uniparentally) FST = 1/(2Nm+1)
* The statistical properties of FST are not well worked out, but they're ugly - see the figures
* Dispersal rates for genetic purposes are often quite different than what is needed fro ecological studies
=> Genetic dispersal only counts if the migrants reproduce effectively
=> Genetic dispersal only counts if the reproduction of migrant individuals is equal to resident individuals (i.e., migrants have to move before their reproductive life starts)
=> Selection can over-amplify migrant genetic contributions
* Problems of scale : Genetic analysis only tells you about migration at the geographical scale at which the samples are drawn from.