Evolution in metapopulations
Most organisms live in metapopulations, small groups or clusters of breeding individuals distributed across patchy environments. The populational processes of local extinction, recolonization, and interdemic migration have important affects on the evolutionary trajectory of any species with this kind of population genetic structure.
Although coordinated gene interactions (epistasis) are ubiquitous in development of all complex adaptations, epistasis has not yet been incorporated into evolutionary genetic theory. Epistatic gene interactions play a more important role in evolution in metapopulations than they do in evolution in very large, randomly mating populations. Metapopulations facilitate the origin of evolutionary novelties and complex adaptations in two ways: (1) they limit the ability of recombination to break apart gene complexes; and (2) they have unique processes, like interdemic selection, for promoting the spread of epistatic gene complexes.
Evolutionary genetics of maternal effects
Genes with maternal effects play a central role in early development in most metazoans and in reproductive isolation in interspecific hybrids. The evolutionary genetics of maternal effects not only shares the kin-structure of behavioral evolution but also offers unique opportunities for the evolution of epistatic gene interactions between maternal and offspring genotypes.
Sexual selection and alternative male mating strategies
Sexual selection is one of the strongest and fastest evolutionary processes even though it operates generally in only one sex and in only one life history stage. Owing to strong frequency-dependent selection during reproductive competition, male reproductive polymorphisms, called alternative mating strategies, are common in many organisms. Often they involve switching during male development from one morphology to another.
For endosymbiotic and pathogenic microorganisms, each host individual can be viewed as a component of the symbionts metapopulation. The co-evolution of hosts and their pathogens and symbionts can only be understood from the perspective of evolution in genetically subdivided populations.