Multilocus tests of Pleistocene refugia and ancient divergence in a pair of Atlantic Forest antbirds (Myrmeciza)

• Published in: Molecular ecology 2013-08, Vol.22 (15), p.3996-4013
• Main Authors: Raposo do Amaral, Fábio, Albers, Patrick K., Edwards, Scott V., Miyaki, Cristina Y.
• Format: Article
• Language: English
• Subjects: Animals; anonymous loci; Atlantic Forest; Biodiversity; Biological and medical sciences; Biological evolution; Birds; DNA, Mitochondrial - genetics; Ecosystem; Evolution, Molecular; Forestry; Fundamental and applied biological sciences. Psychology; Gene loci; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Genetic Markers - genetics; Genetic Variation; Genetics of eukaryotes. Biological and molecular evolution; Haplotypes - genetics; multilocus phylogeography; Passeriformes - genetics; Phylogeography; Population genetics, reproduction patterns; refugia theory; Reproductive Isolation; Sequence Analysis, DNA
• ISSN: 0962-1083; 1365-294X
• DOI: 10.1111/mec.12361

The Atlantic Forest (AF) harbours one of the most diverse vertebrate faunas of the world, including 199 endemic species of birds. Understanding the evolutionary processes behind such diversity has become the focus of many recent, primarily single locus, phylogeographic studies. These studies suggest that isolation in forest refugia may have been a major mechanism promoting diversification, although there is also support for a role of riverine and geotectonic barriers, two sets of hypotheses that can best be tested with multilocus data. Here we combined multilocus data (one mtDNA marker and eight anonymous nuclear loci) from two species of parapatric antbirds, Myrmeciza loricata and M. squamosa, and Approximate Bayesian Computation to determine whether isolation in refugia explains current patterns of genetic variation and their status as independent evolutionary units. Patterns of population structure, differences in intraspecific levels of divergence and coalescent estimates of historical demography fit the predictions of a recently proposed model of refuge isolation in which climatic stability in the northern AF sustains higher diversity and demographic stability than in the southern AF. However, a pre‐Pleistocene divergence associated with their abutting range limits in a region of past tectonic activity also suggests a role for rivers or geotectonic barriers. Little or no gene flow between these species suggests the development of reproductive barriers or competitive exclusion. Our results suggests that limited marker sampling in recent AF studies may compromise estimates of divergence times and historical demography, and we discuss the effects of such sampling on this and other studies.