Research Fellow @cobig2 | Staff @eseb2013 Faculty of Sciences of the University of Lisbon Department of Animal Biology Computational Biology & Population Genomics Group Campo Grande, Building C2, Floor 3, Room 22 Lisbon, 1749-016 Portugal Website
Author(s): Seabra, SG, Rodrigues AS, Silva SE, Silva J, Marabuto E, Pina-Martins F, Gharbi K, Blaxter M, Borges PAV, Jiggins C, Quartau JA, Paulo OS
Philaenus spumarius (Insecta, Hemiptera, Aphrophoridae) has for long been a subject of interest of evolutionary biologists due to its heritable colour polymorphism that shows evidence of balancing selection and of clinal variation in the colour mophs frequencies. We are studying the adaptive significance of this polymorphism, particularly to understand if the melanic morphs (e.g. “marginellus” morph) have any advantage/disadvantage in terms of survival and reproductive success, efficiency of egg maturation and resistance to desiccation compared to non-melanic morphs (“typicus” and “trilineatus”). Results so far indicate a higher survival, higher number of eggs clutches and higher number of eggs laid by the “trilineatus” females than “typicus” or “marginellus” females. We are also taking a genomic approach for a) the identification of genetic basis of the colour polymorphism and b) for detecting signatures of balancing and directional selection in the genome of P. spumarius. For this purpose we are applying RAD sequencing in a) a set of samples from the three different morphs referred above, using a high frequency cutter enzyme (PstI) and in b) another set of samples from 8 populations across the distribution range of the species representing the main mitochondrial haplogroups, using a lower frequency cutter enzyme (SbfI). We are also assembling a draft of the genome that will aid in the identification of homologous regions to available references, although the very large genome size of this insect constitutes an extra challenge.
Author(s): Rodrigues, AS, Silva SE, Marabuto E, Silva DN, Silva J, Wilson MR, Thompson V, Yurtsever S, Halkka A, Gharbi K, Blaxter M, Borges PAV, Quartau JA, Jiggins C, Paulo OS, Seabra SG
We investigated the evolutionary history of the meadow spittlebug Philaenus spumarius, a widespread and polyphagous insect species of the Holarctic region, limited in its range by the presence of enough humidity in the earlier life stages, and that has a remarkable dorsal colour/pattern polymorphism of the adults. The mitochondrial gene cytochrome c oxidase subunit I (COI) revealed three main haplogroups in Europe: the “western”, the “eastern-Mediterranean” and the “north-eastern” haplogroups, which overlapped in some regions. Evidence of recent divergence events at less than one million years ago in southern Mediterranean peninsulas followed by northward population expansions were found. Recent gene-flow events between the main southern peninsulas and between the Iberian Peninsula and North Africa were also detected. A probable British origin for the insular populations of the Azores and New Zealand was revealed, as well as multiple geographic origins for North American populations from western and northern Europe.
Restriction site associated DNA (RAD) sequencing was also applied in a set of 8 populations from the different mitochondrial haplogroups and the differentiation patterns obtained from a set of over 15,000 SNPs were concordant with COI results and with a better resolved tree.