The niche conservatism hypothesis states that related species diverge in niche characteristics at lower rates than expected, given their lineage divergence. Here we analyze whether niche conservatism is a common pattern among vector species (Hemiptera: Reduviidae: Triatominae) of Trypanosoma cruzi that inhabit North and Central America, a highly heterogeneous landmass in terms of environmental gradients. Mitochondrial and nuclear loci were used in a multi-locus phylogenetic framework to reconstruct phylogenetic relationships among species and estimate time of divergence of selected clades to draw biogeographic inferences. Then, we estimated similarity between the ecological niche of sister species and tested the niche conservatism hypothesis using our best estimate of phylogeny. Triatoma is not monophyletic. A primary clade with all North and Central American (NCA) triatomine species from the genera Triatoma, Dipetalogaster, and Panstrongylus, was consistently recovered. Nearctic species within the NCA clade ( T. p. protracta, T. r. rubida) diverged during the Pliocene, whereas the Neotropical species ( T. phyllosoma, T. longipennis, T. dimidiata complex) are estimated to have diverged more recently, during the Pleistocene. The hypothesis of niche conservatism could not be rejected for any of six sister species pairs. Niche similarity between sister species best fits a retention model. While this framework is used here to infer niche evolution, it has a direct impact on spatial vector dynamics driven by human population movements, expansion of transportation networks and climate change scenarios.
Knowledge regarding the evolutionary history of insect vectors of pathogens is essential to design precise and appropriately integrated control strategies, since species' dispersal and invasive capacity are key components to prevent human-vector interaction. Given several well-known invasive or dispersal events of Triatominae, and their adaptive capacity to colonize modified habitats, the question arises whether niche conservatism (i.e. the limited capacity for niche differentiation within clades) across sister species could influence distribution patterns. Niche conservatism is herein analyzed across the highly heterogeneous landmass of North and Central America where most species complexes of the Triatominae are vectors of Trypanosoma cruzi. Since phylogenetic relationships among and within triatomine species complexes are still ill-defined, we first used a multi-locus phylogenetic analysis using mitochondrial and nuclear loci to validate relationships between species. Similarity of the ecological niche between six sister species' pairs was used to test the niche conservatism hypothesis. The results provide robust evidence of monophyly for North and Central America triatomine species. The hypothesis of niche conservatism was not rejected for any sister species pair, independently of niche width, distribution range, biogeographic affinity, or environmental heterogeneity; niche similarity correlated inversely with taxa divergence and according to a retention model.