Local adaptation

[5] However, evidence for rapid local adaptation in mobile animals has been gathered through transplant experiments with Trinidadian guppies.

[6] Several meta-analyses have attempted to quantify how common local adaptation is, and generally reach similar conclusions.

Roughly 75% of transplant experiments (mostly with plants) find that local populations outcompete foreign populations at a common site, but less than 50% find the reciprocal home site advantage that defines classic local adaptation.

[14] However gene flow can also introduce beneficial alleles to a population, which increases the amount of genetic variation, therefore strengthening the likelihood of local adaptations.

[16] It is possible for genetic material such as pollen or spores that can travel via wind, water or being brought by an animal, to reach an isolated population.

[18] A specific local adaptation of the P. biglumis is having a small number of offspring and putting more energy towards defenses against potential intruders, which would help prevent the parasitic wasp from entering the nest.

[14] Looking at different local populations with similar levels of gene flow is particularly important because the presence of local adaptations in some populations but not others could suggest factors other than gene flow and selective pressure from parasites are causing the differences.

The Alps were chosen as the area for the wasp study because the elevation of the mountains separate regional and local populations; resulting in multiple local populations of both host and parasite at different elevations and regions.

[14] For example, wasps on the same mountain but at different elevations do interbred so gene flow is occurring between local populations.

[14] This evidence supports the idea that some level of isolation is needed in order for local adaptations to occur within populations, further supporting the idea that high levels of gene flow do not produce local adaptations.

There was study done on fruit flies (Drosophila melanogaster) to see if adaptive potential was increased in populations that were previously isolated and then experienced different levels of gene flow, or complete hybridization between two populations of previously isolated fruit flies.

Hypothetical results from two reciprocal transplant experiments, in which organisms from site1 and site2 are transplanted to both sites and their performance compared. In both experiments (panels), the local sources outcompete the foreign sources, indicating that populations are locally adapted. In the left panel each source also does best at its home site. In the right panel site1 is higher quality than site2, so both populations do best in site1, even though the population from site2 is locally adapted to its poor quality site.