Speciation and evolutionary dynamics of asymmetric mating preference.

摘要

A scenario of speciation history and asymmetric mating preference was developed, incorporating invasion dynamics via frequency-dependent interspecific sexual competition. A newly isolated (derived) species may form at the periphery of the ancestralspecies' distribution by invading a new range. Only a few closely related species would be expected in the new area, while many related species are expected to coexist with the ancestral species. In a peripherally derived species, female mating preferences should be relaxed through sexual character release, owing to a lack of sympatric species and a scarcity of intraspecific mating opportunities. Secondary contacts may then happen as repeated invasions or backward invasions. Repeated invasions could lead to the coexistence of both the derived species and the newly invading ancestor. Backward invasions by the derived species can succeed only when the derived females develop a strict mating discrimination against the ancestral males. Strong character displacement was expected in the derived species. Thus, peripheral isolation and repeated invasions lead to the relaxed female mating preferences in the derived species and backward invasions lead to stronger female mating preferences in the derived species. This model was shown to agree with data on Drosophila from Hawaii and the continents. Experimental data on the Drosophila arizonae-mojavensis species cluster also supported the hypothesis.