Ecological character displacement in competing common green lacewings in Europe: a route to speciation?

Competitive interactions among the three common green lacewing species of the Chrysoperla complex in Europe are presented. Four morphological characters were registered as semi-quantitative traits to assess variation between populations. Data were obtained from 325 adults originating from 14 locations. A statistical approach was performed in conjunction with observations of ecological traits and a survey of genetic relationships assessed by mitochondrial DNA cytochrome b analysis. The results indicate character displacement in Chrysoperla affinis when living in sympatry with Chrysoperla carnea. The morphological traits of Ch. affinis sympatric with Ch. carnea differ from those of allopatric Ch. affinis, although the genetic distance between those strains was weak. This was associated with a large difference in microhabitats and premating behaviour. Variation in courtship songs manifests a process of speciation within related populations. Thus, that ecological switching can also promote character displacement is supported. This suggests that character displacement acts through phenotypic variability and mediates negative interactions among species. These findings suggest that the highest rate of speciation occurs in groups of species in which competition is the strongest. (C) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 292-300.