Title

Species boundaries in European green lacewings of the Chrysoperla carnea group

Date of Completion

January 2010

Keywords

Biology, Ecology|Biology, Entomology|Biology, Evolution and Development

Degree

Ph.D.

Abstract

Among insects that duet, instances of females singing are few, and it is even rarer for females to produce a sound that is species-specific and similar to males. The Chrysoperla carnea group of green lacewings (Neuroptera: Chrysopidae) has recently experienced rapid speciation. Both sexes exchange species-specific mating signals in a duet during courtship and mating. These songs are hypothesized to be important in intraspecific and interspecific mate recognition. ^ I compared patterns of reproductive isolation among five European species within the species complex as well as sex differences in mating strategies. The mating signals clearly contributed to reproductive isolation among the species. In addition, those species that responded more frequently to conspecific signals were less discriminating against heterospecific signals, suggesting differences in mating strategies among species. Sexual dimorphism in mating preference was significant in C. agilis and less so in C. lucasina. Males of C. agilis were more responsive to all signals and less discriminating against heterospecific signals compared to females. ^ Sexual dimorphism may be the result of resolved sexual conflict. I measured and compared sex-specific song characters and preferences of Chrysoperla lucasina from three geographical populations. I found minor but significant sexual dimorphism of preferences and song characters in this species. Females and males had conflicting preferences, and while the songs produced by the sexes were similar in consisting of multiple volleys, they were dimorphic in volley duration and period. Volley durations matched the preferences of the opposite sex but volley periods did not, indicating differential selection or disparate evolutionary histories for these song characters. The overall results indicate sexually antagonistic selection. ^ I hybridized Chrysoperla agilis and C. carnea in order to identify patterns of inheritance of courtship songs and preference for species-specific songs. The preferences and songs of hybrids resembled C. agilis more when it was the maternal parent. Relatedness of a hybrid cross to C. agilis was a better predictor of its preference than its song. It is likely that songs and preferences in the two species share the same underlying genetic architecture. However the genetic loci underlying song and preference are most likely independent. ^