In 1985, Williams wrote, "If some populations of species are doing better than others at persistence and reproduction, and if such differences are caused in part by genetic differences, this selection at the population level must play a role in the evolution of the species," while concluding that group selection "is unimportant for the origin an maintenance of adaptation" (Williams 1985, pp. 7 8).
Taken together, these studies have noted maintenance of adaptation and control.
A central theme in evolutionary ecology is understanding the origin and maintenance of adaptations shaped by natural selection.
Such trait decay, especially when occurring in parallel in independent lineages, highlights the importance of natural selection for the maintenance of adaptations (Fong et al., 1995; Wiens, 2001; Lahti et al., 2009).
Additionally, V. inaequalis is described as a good model for host adaptation in plant pathogens [ 7] because mating only occurs between strains that are able to infect identical hosts, thus facilitating the maintenance of adaptations to a host when host ranges do not overlap [ 18, 19].
Populations of the most important malaria vector in tropical Africa, i.e. Anopheles gambiae sensu stricto, offer instances of recent niche expansion [ 17, 18] that can provide us with insights about the ecological and molecular mechanisms underlying the emergence and maintenance of adaptations.
At the population level, this process requires an organismal architecture in which the maintenance of local adaptation does not preclude the ability to innovate in the same traits and their continuous evolution.
Carbohydrate metabolism and lipid degradation may also be involved in supplying energy that is required for maintenance of drought adaptation and osmoprotectant synthesis through breakdown of energy reserves.
In this clade, selfing lineages occur in the most extreme habitats, likely linked with reproductive assurance and the maintenance of local adaptation.
The maintenance of viral adaptations may therefore reflect ongoing T-cell pressure in chronic HCV-infected subjects.
Although host fidelity has proved to encourage the host adaptation through continual use of the same host species (Forbes et al. 2009), by itself it is not sufficient for the formation and maintenance of host adaptations in parasitoid populations, even under reduced gene flow between populations.
