Sexual conflict promotes speciation in insects

Speciation rates among extant lineages of organisms vary extensively, but o ur understanding of the causes of this variation and, therefore, the proces ses of speciation is still remarkably incomplete. Both theoretical and empi rical studies have indicated that sexual selection is important in speciati on, but earlier discussions have focused almost exclusively on the potentia l role of female mate choice. Recent findings of postmating reproductive co nflicts of interest between the sexes suggest a quite different route to sp eciation. such conflicts may lead to perpetual antagonistic coevolution bet ween males and females and may thus generate rapid evolutionary divergence of traits involved in reproduction. Here, we assess this hypothesis by cont rasting pairs of related groups of insect species differing in the opportun ity for postmating sexual conflict. Groups where females mate with many mal es exhibited speciation rates four times as high as in related groups where females mate only once. Our results not only highlight the general importa nce of postmating sexual selection in speciation, but also support the rece nt suggestion that sexual conflict is a key engine of speciation.