Evidence for an intrinsic factor promoting landscape genetic divergence in Madagascan leaf-litter frogs

Abstract

The endemic Malagasy frog radiations are an ideal model system to study patterns and processes of speciation in amphibians. Large-scale diversity patterns of these frogs, together with other endemic animal radiations, led to the postulation of new and the application of known hypotheses of species diversification causing diversity patterns in this biodiversity hotspot. Both extrinsic and intrinsic factors have been studied in a comparative framework, with extrinsic factors usually being related to the physical environment (landscape, climate, river catchments, mountain chains), and intrinsic factors being clade-specific traits or constraints (reproduction, ecology, morphology, physiology). Despite some general patterns emerging from such large-scale comparative analyses, it became clear that the mechanism of diversification in Madagascar may vary among clades, and may be a multifactorial process. In this contribution, I test for intrinsic factors promoting population-level divergence within a clade of terrestrial, diurnal leaf-litter frogs (genus Gephyromantis) that has previously been shown to diversify according to extrinsic factors. Landscape genetic analyses of the microendemic species Gephyromantis enki and its widely distributed, larger sister species Gephyromantis boulengeri over a rugged landscape in the Ranomafana area shows that genetic variance of the smaller species cannot be explained by landscape resistance alone. Both topographic and riverine barriers are found to be important in generating this divergence. This case study yields additional evidence for the probable importance of body size in lineage diversification.

Diversification of the rainfrog Pristimantis ornatissimus in the lowlands and Andean foothills of Ecuador

“…We show, for example, how color patterns can be delimited by geographic barriers (i.e. rivers, elevational gradients), which have also been suggested in other amphibians [52,53,54,55]. Additionally, we show that genetic differentiation between sister species ( P .…”

Testing the role of ecology and life history in structuring genetic variation across a landscape: a trait‐based phylogeographic approach

“…Our data set also covered a larger phylogenetic diversity, including species from several taxonomic families, which may explain why we recovered a greater number of significant explanatory variables in addition to body size (Pabijan et al . ; Wollenberg Valero ).…”

“…Larger animals showed less genetic divergence among populations, implying they have higher dispersal capacity than smaller species (Pabijan et al . ; Wollenberg Valero ). Larger frogs may be better dispersers simply because of scale (they can move faster than smaller frogs) or may be better survivors, for example better able to resist desiccation.…”

“…), here, we study a diversity of species across a single landscape in a comparative phylogeographic approach. Finally, we ask whether life‐history traits themselves, such as developmental mode and body size, limit dispersal ability and thereby predict variation among species in pairwise genetic divergence between populations (Wollenberg Valero ). This latter approach is rarely attempted, but could become more common as phylogeographic studies are eventually applied to whole communities, for example, through DNA barcoding campaigns (e.g.…”

Gene-flow in the clouds: landscape genetics of a viviparous, montane grassland toad in the tropics

“…In general, it is assumed that amphibians are highly philopatric and poor dispersers (Smith and Green 2005), and that life-history traits, as for example body size and reproductive mode, are important for population structure (Measey et al 2007;Wollenberg-Valero 2015). We found the global Nimba toad populations to be structured in three distinct subpopulations.…”