Abstract
Previous research revealed complex diversification patterns in the parthenogenetic weevil Naupactus cervinus. To understand the origin of clonal diversity and successful spreading of this weevil, we investigated its geographic origin and possible dispersal routes and whether parthenogens can persist in habitats under unsuitable environmental conditions. This study is based on samples taken throughout a broad area of the species’ range. We used both mitochondrial and nuclear markers and applied phylogenetic and network analyses to infer possible relationships between haplotypes. Bayesian phylogeographic analyses and ecological niche modeling were used to investigate the processes that shaped genetic diversity and enabled the colonization of new geographic areas. Southeastern Brazil emerges as the original distribution area of N. cervinus. We detected two range expansions, one along natural corridors during the Pleistocene and the other in countries outside South America during recent times. Isolation due to climate shifts during the early Pleistocene led to diversification in two divergent clades, which probably survived in different refugia of the Paranaense Forest and the Paraná River delta. The origin of the clonal diversity was probably a complex process including mutational diversification, hybridization, and secondary colonization. The establishment of N. cervinus in areas outside its native range may indicate adaptation to drier and cooler conditions. Parthenogenesis would be advantageous for the colonization of new environments by preventing the breakup of successful gene combinations. As in other insect pests, the present distribution of N. cervinus results from both its evolutionary history and its recent history related to human activities.
Highlights
Asexual reproduction has long been claimed to be an evolutionary dead end due to the accumulation of deleterious mutations
In previous contributions we demonstrated that Naupactus cervinus is a species complex with some divergent parthenogenetic lineages that are still undergoing speciation (Rodriguero et al 2013)
We provided information concerning the nuclear and mitochondrial genetic diversity of the species across a large portion of its geographic range (Rodriguero et al 2010a, 2013). We concluded that both parthenogenesis and Wolbachia infection have left an imprint on its genomes, such as coevolution between nucleus and mitochondria, indicating the ancient origin of asexual reproduction (Rodriguero et al 2010b)
Summary
Asexual reproduction has long been claimed to be an evolutionary dead end due to the accumulation of deleterious mutations. We provided information concerning the nuclear and mitochondrial genetic diversity of the species across a large portion of its geographic range (Rodriguero et al 2010a, 2013) We concluded that both parthenogenesis and Wolbachia infection have left an imprint on its genomes, such as coevolution between nucleus and mitochondria, indicating the ancient origin of asexual reproduction (Rodriguero et al 2010b). Asexual reproduction generally limits adaptive potential for colonizing new habitats, but preexisting adaptations and habitat tolerance of parthenogens are key factors contributing to a successful outcome In this context, colonization most likely relies on genetically diverse founding populations or multiple introductions (Dlugosch and Parker 2008). To unravel the origin of genetic variation in N. cervinus, the factors that shaped its spatial distribution, and the possible causes underlying its successful spread, we carried out a phylogeographic study coupled to an ecological niche modeling analysis to accurately recover the evolutionary history of this weevil
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