Drosophila simulans' response to laboratory selection for tolerance to a toxic food source used by its sister species D. sechellia

摘要

Drosophila sechellia is a specialist species which feeds and breeds on a toxic plant. Mo-rinda eitrifolia. All other Drosophila species are killed by ripe fruits of Morinda. D. sinmlans was subjected to laboratory selection for survival in presence of octanoic acid, the toxic compound of M. citrifolia. After 20 generations of selection, selected lines showed an increased tolerance to octanoic acid, although the response was small compared to the interspecific differences. The genetic response to selection was assessed by studying the changes in allele frequencies at 28 mierosatellite loci. Three loci, located in three distinct genomic regions, showed changes in allele frequencies significantly different from what is expected under drift alone in the selected lines. An oligogenic determination for tolerance to octanoic acid is in agreement with published results based on interspecific crosses.