Damselflies of Patagonia, a phylogeographic study utilizing EPIC DNA and mitochondrial sequence markers

PESSACQ, PABLO; BYBEE, SETH M.; KING, TAYLOR; ARNOLD, PRESTON; ANJOS DOS SANTOS D.; MORANDO, MARIANA

La Plata

Congreso; International Congress of Odonatology - ICO2015; 2015

Worldwide Dragonfly Association y Societas Internationalis Odonatologica

We conducted the first phylogeographic study of Patagonian insects, for which we selected the two most widely distributed species of Odonata in the region: Rhionaeshna variegata (Aeshnidae) and Cyanallagma interruptum (Coenagrionidae). First, we performed a preliminary analysis of nine populations of both species from most of their distribution range, and we sampled the nuclear genesH3 and 28S, and the mitochondrial genes 16S, COXI and COXII. While R. variegata showed no genetic structure, C. interruptum showed genetic structure for COXI/II and 16S. These results are consistent with a greater dispersal ability among aeshinds as compared with coenagrionids. Thus, we pursued further analyses for C. interrumptum, for which we included eleven additional populations (20 populations and54 specimens total) that cover most of its distributional range in Argentina. We performed network and phylogeographic analyses with the mitochondrial genes COXI/II and with the recently developed EPIC (exon-primed intron-crossing) nuclear genes PRMT, CDC5 and AgT. The mtDNA results show that C.interruptum consists of two major clades with considerable genetic differences, one distributed in the north (Northern Patagonia) and one in the south (central Patagonia). Individuals from a small area in between these two regions (southwestern Río Negro) have haplotypes recovered from both clades.This pattern is concordant with a separation of the ancestral population in the past and the posterior secondary contact in the intermediate localities. It is probable that events during the Pleistocene(glaciation cycles and associated changes in climate and/or other geological events) interrupted geneow among northern and southern populations. The nuclear genes showed a high level of heterozygosity but low levels of genetic structure with no signals of geographic structure. The incongruence between the two types or markers allow us to elaborate two non-exclusive main hypotheses: 1) females may have lower dispersal capacity or high philopatry compared to males, 2)the temporal separation between the two populations was relatively brief providing enough time for mitochondrial markers to differentiate genetically, but not sufficiently long to be reflected by the more constrained evolutionary rates of the nuclear genes.