User:ZEDiphe

Definition of local adaptation
Local Adaptation results from the interactions between multiple evolutionary forces (selection, genetic drift, mutation,  migration) and is observable on human timescale. Evolution of species in spatially and temporally heterogeneous environnement generates different selective pressures. Unlike adaptation to physical environment, local adaptation is based on the evolution of one species in response to recent evolutionary changes in an other species. That is why, there is a constant co-adaptation between competitors (parasitism, predation) and mutualists, selecting or maintaining the frequency of traits acting in survival and/or reproduction. This dynamic process favors local coevolution and specialization of the two partners of the interaction. Local adaptation can be effected both on a large geographic scale (between populations of one species separated by hundreds kilometers), microgeographically (less than 1 kilometer) and even throught times (seasonnal change).

Modification in selection pressures can facilitate adaptation by increasing local genetic variation. Those modifications are often found in the context of antagonistic interactions, where coevolution is fast and results in ‘arms race’ in which organisms must constantly adapt, evolve, and survive against ever-evolving opposing organisms in an ever-changing environment. In such interactions, the one evolving the most rapidly, having a shorter generation time or higher mutation or migration rate, is locally adapted while the other is not. Local adaptation can be evaluated by comparing fitness of the interacting agents in sympatry than in allopatry.

Examples of local adaptation

 * In lakes in New Zealand, Microphallus sp. trematodes are more adapted to Potamopyrgus antipodarum snails with sexual reproduction from shallow-water area than to deeper-water snails with an asexual reproduction.


 * Local adaptation can be made by 'Daphnia magna'' under environnement stress by changing their phototactic behavior and their life-history traits (body and eggs size, number of eggs).


 * The soil fertility is key driver of local adaptation in arbuscular mycorrhizal (AM) symbioses. Locally adapted mycorrhizal associations are more mutualistic in phosphorus limited sites and less parasitic at nitrogen limited sites depending on plants-soils-fungi combination.