Search

Background: During past glacial periods, many species of forest-dwelling animals experienced range contractions. In contrast, species living outside such moist habitats appear to have reacted to Quaternary changes in different ways. The Atlantic Forest represents an excellent opportunity to test phylogeographic hypotheses, because it has a wide range of vegetation types, including unforested habitats covered predominantly by herbaceous and shrubby plants, which are strongly influenced by the harsh environment with strong wind and high insolation. Here, we investigated the distribution of genetic diversity in the endemic sand dune ant Mycetophylax simplex across its known range along the Brazilian coast, with the aim of contributing to the understanding of alternative phylogeographic patterns. We used partial sequences of the mitochondrial gene cytochrome oxidase I and nuclear gene wingless from 108 specimens and 51 specimens, respectively, to assess the phylogeography and demographic history of this species. To achieve this we performed different methods of phylogenetic and standard population genetic analyses., Results: The observed genetic diversity distribution and historical demographic profile suggests that the history of M. simplex does not match the scenario suggested for other Atlantic Forest species. Instead, it underwent demographic changes and range expansions during glacial periods. Our results show that M. simplex presents a shallow phylogeographic structure with isolation by distance among the studied populations, living in an almost panmictic population. Our coalescence approach indicates that the species maintained a stable population size until roughly 75,000 years ago, when it underwent a gradual demographic expansion that were coincident with the low sea-level during the Quaternary. Such demographic events were likely triggered by the expansion of the shorelines during the lowering of the sea level., Conclusions: Our data suggest that over evolutionary time M. simplex did not undergo dramatic range fragmentation, but rather it likely persisted in largely interconnected populations. Furthermore, we add an important framework about how both glacial and interglacial events could positively affect the distribution and diversification of species. The growing number of contrasting phylogeographic patterns within and among species and regions have shown that Quaternary events influenced the distribution of species in more ways than first supposed.

Background: Lutzomyia gomezi (Nitzulescu, 1931) is one of the main Leishmania (Vianna) panamensis vectors in Panama, and despite its medical significance, there are no population genetic studies regarding this species. In this study, we used the sequences of the mitochondrial gene cytochrome b/start of NADH1 and the nuclear elongation gene α-1 in order to analyze genetic variation and phylogeographic structure of the Lu. gomezi populations., Methods: A total of 86 Lu. gomezi individuals were captured in 38 locations where cutaneous leishmaniasis occurred. DNA was extracted with phenol/chloroform methods and amplification of genes was performed using PCR primers for mitochondrial and nuclear markers., Results: We found a total of 37 and 26 haplotypes of mitochondrial and nuclear genes, high haplotype diversity (h) for all three populations were detected with both molecular markers. Nucleotide diversity (π) was estimated to be high for all three populations with the mitochondrial marker, which was opposite to the estimate with the nuclear marker. In the AMOVA Φst recorded moderate (mitochondrial) and small (nuclear) population structure with statistical significance among populations. The analysis of the fixation index (Fst) used to measure the differentiation of populations showed that with the exception of the population located in the region of Bocas del Toro, the other populations presented with minor genetic differentiation. The median-Joining network of the mitochondrial marker reveled three clusters and recorded four haplotypes exclusively of localities sampled from Western Panama, demonstrating strong divergence. We found demographic population expansion with Fu´s Fs neutrality test. In the analysis mismatch distribution was observed as a bimodal curve., Conclusion: Lu. gomezi is a species with higher genetic pool or variability and mild population structure, due to possible capacity migration and local adaptation to environmental changes or colonization potential. Thus, knowledge of the genetic population and evolutionary history is useful to understand the implications of different population genetic structures for cutaneous leishmaniasis epidemiology.