Abstract
BackgroundThe common vampire bat Desmodus rotundus is an excellent model organism for studying ecological vicariance in the Neotropics due to its broad geographic range and its preference for forested areas as roosting sites. With the objective of testing for Pleistocene ecological vicariance, we sequenced a mitocondrial DNA (mtDNA) marker and two nuclear markers (RAG2 and DRB) to try to understand how Pleistocene glaciations affected the distribution of intraspecific lineages in this bat.ResultsFive reciprocally monophyletic clades were evident in the mitochondrial gene tree, and in most cases with high bootstrap support: Central America (CA), Amazon and Cerrado (AMC), Pantanal (PAN), Northern Atlantic Forest (NAF) and Southern Atlantic Forest (SAF). The Atlantic forest clades formed a monophyletic clade with high bootstrap support, creating an east/west division for this species in South America. On the one hand, all coalescent and non-coalescent estimates point to a Pleistocene time of divergence between the clades. On the other hand, the nuclear markers showed extensive sharing of haplotypes between distant localities, a result compatible with male-biased gene flow. In order to test if the disparity between the mitochondrial and nuclear markers was due to the difference in mutation rate and effective size, we performed a coalescent simulation to examine the feasibility that, given the time of separation between the observed lineages, even with a gene flow rate close to zero, there would not be reciprocal monophyly for a neutral nuclear marker. We used the observed values of theta and an estimated mutation rate for the nuclear marker gene to perform 1000 iterations of the simulation. The results of this simulation were inconclusive: the number of iterations with and without reciprocal monophyly of one or more clades are similar.ConclusionsWe therefore conclude that the pattern exhibited by the common vampire bat, with marked geographical structure for a mitochondrial marker and no phylogeographic structure for nuclear markers is compatible with a historical scenario of complete isolation of refuge-like populations during the Pleistocene. The results on demographic history on this species is compatible with the Carnaval-Moritz model of Pleistocene vicariance, with demographic expansions in the southern Atlantic forest.
Highlights
The common vampire bat Desmodus rotundus is an excellent model organism for studying ecological vicariance in the Neotropics due to its broad geographic range and its preference for forested areas as roosting sites
Paleopalinogical studies demonstrate that the Neotropical forested areas have been very dynamic: the Atlantic forest and the Amazon were connected in the past [3,4], becoming separated as increasing aridity in the Tertiary triggered the formation of the belt of xeromorphic formations between them [5]
The TNT program generated as outfile a matrix showing presence/absence of reciprocal monophyly for each of the Molecular variation For the mitochondrial marker, 118 individuals were sampled from 54 localities
Summary
The common vampire bat Desmodus rotundus is an excellent model organism for studying ecological vicariance in the Neotropics due to its broad geographic range and its preference for forested areas as roosting sites. With the objective of testing for Pleistocene ecological vicariance, we sequenced a mitocondrial DNA (mtDNA) marker and two nuclear markers (RAG2 and DRB) to try to understand how Pleistocene glaciations affected the distribution of intraspecific lineages in this bat. Paleopalinogical studies demonstrate that the Neotropical forested areas have been very dynamic: the Atlantic forest and the Amazon were connected in the past [3,4], becoming separated as increasing aridity in the Tertiary triggered the formation of the belt of xeromorphic formations between them [5]. There seemed to be a predominance of arboreal vegetation during most of the Pleistocene with Amazonic and Atlantic forest tree species in areas that today lie in the dry diagonal that separates these two biomes [see [6,7]]. The extent to which these climatic fluctuations and associated vegetation changes affected the patterns of distribution and diversification of the fauna remains a central question in understanding the evolution of forest-associated taxa
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