Abstract
<title>Abstract</title> <p>The role of geological and climatic events in driving intraspecific diversification in widely distributed insects in the Neotropic has been understudied. We investigated the genealogic relationships within and among populations of the dung beetle Canthon cyanellus from Mexico and Colombia using nuclear (ITS2) and mitochondrial (16S, COI) genetic markers to determine how past climatic fluctuations and geological events have shaped their demography and diversification. Our results revealed significant genetic variation across the sampled regions. The mtDNA region was the most informative, showing a gradient in genetic diversity. Analyses of all three markers indicated a historical demographic dynamic characterized by population expansions during interglacial and interstadial periods. Mainly, during the Pleistocene the populations of this species have diverged into seven clades in Mexico and two in Colombia. The genetic structure is consistent with a pattern of historical isolation by distance. In Colombia, the recovered clades agree with variation in color, and the genetic distinctiveness suggests that those clades might represent cryptic species. Pleistocene climatic changes, coupled with geological events such as the Andean uplift, were significant drivers of population divergence. The divergence between the Mexican and Colombian populations (ca. 2.81 Myr) coincides with the early formation of the Isthmus of Panama. This temporal correlation concurs with the hypothesis of a dispersal pathway from South America to North America.</p>