Trends in the Changes of Postgonite Forms during the Evolution of Grass Flies of the Genus Meromyza (Diptera, Chloropidae)

Grass flies of the genus Meromyza have been grouped by the COI mtDNA locus into several clusters, which corresponds to the morphological characteristics of the anterior processes of postgonites (APs) in the male genital apparatus. In the present study, the strategies of changes in the form of APs that have developed during the evolution of the group have been investigated. To study the ways of transformation of the AP form in 24 species from seven clusters, the AP contours of evolutionarily younger species were compared with species close to the ancestral haplotypes of the group. Three groups of species have been revealed. The approach of applying the phylogenetic tree (MrBayes program) to the results of geometric morphometry (MorphoJ program) has been used. Three areas corresponding to the previously found species groups and the area of the species close to the ancestral haplotypes have been identified. The comparison of the results of the applied methods show common microevolutionary directions in the transformation of the AP form associated with transformation of its projecting part (PAP).