Molecular and acoustic signal evolution in Mediterranean species of Cicada L. (Insecta: Cicadoidea)

Tese de doutoramento em Biologia (Biologia Evolutiva), apresentada à Universidade de Lisboa através da Faculdade de Ciências, 2008Cicadas are widely distributed in the Mediterranean area and are mainly identified by male acoustic signals, which act as specific mate recognition systems (SMRSs), attracting only conspecific females. Within the genus Cicada Linnaeus several species have diverged in their calling songs without showing external morphological differences. Yet, the degree of genetic differentiation among these species was still mostly undetermined and their phylogenetic relationships were practically unknown. The present study assesses mtDNA sequence variation in a complex of six closely related species of Cicada from the Mediterranean area in order to test the applicability of the SMRS species concept and to determine the phylogenetic relationships and the evolutionary history of this group. The population structure of the two most common species, C. orni and C. barbara was analysed in some detail at the molecular and acoustic levels in order to help explain the present patterns of distribution and to test the congruence between mtDNA and acoustic behaviour divergence. The detection of nuclear copies of mtDNA (Numts) of the cytochrome b gene was crucial for subsequent data analyses. The number of Numts found here is to our knowledge unprecedented in the literature for such a small DNA fragment analysed. The subsequent sequence analysis proved to be of exclusively mitochondrial origin. These analyses confirmed a general congruence between mtDNA and acoustic behaviour divergence at the species and the population levels in the genus Cicada. Each nominal species here analysed constitutes a distinct evolutionary group. Acoustic and mtDNA sequence data also supported the separation of the C. orni Greek populations from the rest of Europe and the separation of Moroccan and Iberian populations of C. barbara. Pleistocene climatic changes and several dispersal barriers, such as mountain ranges and sea barriers, were identified as important factors influencing the life history of these cicadas.Universidade de Lisboa (UL), Centro de Biologia Ambiental; Fundação para a Ciência e Tecnologia (FCT), (BD/18229/98