Mitochondrial Introgression, Color Pattern Variation, and Severe Demographic Bottlenecks in Three Species of Malagasy Poison Frogs, Genus Mantella

Abstract

Madagascar is a biodiversity hotspot particularly rich in amphibian diversity and only a few charismatic Malagasy amphibians have been investigated for their population-level differentiation. The Mantella madagascariensis group is composed of two rainforest and three swamp forest species of poison frogs. We first confirm the monophyly of this clade using DNA sequences of three nuclear and four mitochondrial genes, and subsequently investigate the population genetic differentiation and demography of the swamp forest species using one mitochondrial, two nuclear and a set of nine microsatellite markers. Our results confirm the occurrence of two main mitochondrial lineages, one dominated by Mantella aurantiaca (a grouping supported also by our microsatellite-based tree) and the other by Mantella crocea + Mantella milotympanum. These two main lineages probably reflect an older divergence in swamp Mantella. Widespread mitochondrial introgression suggests a fairly common occurrence of inter-lineage gene flow. However, nuclear admixture seems to play only a limited role in this group, and the analyses of the RAG-1 marker points to a predominant incomplete lineage sorting scenario between all five species of the group, which probably diverged relatively recently. Our demographic analyses show a common, severe and recent demographic contraction, inferred to be in temporal coincidence with the massive deforestation events that took place in the past 1000 years. Current data do not allow to conclusively delimit independent evolutionary units in these frogs, and we therefore refrain to suggest any taxonomic changes.

Population diversification in the frog Mantidactylus bellyi on an isolated massif in northern Madagascar based on genetic, morphological, bioacoustic and ecological evidence

“…An enormous amount of genetic research has also focused on amphibians in Madagascar. Although the majority of these focused on DNA barcoding, phylogenetics and species delimitation, several in-depth studies have assessed the population-level genetic variation of amphibian species (e.g., [ 35 – 42 ]). Because amphibians–especially small-sized species–have a limited dispersal capacity compared to other groups of terrestrial vertebrates, and due to their usually biphasic lifestyle often having specific requirements of both aquatic and terrestrial habitats, they constitute a suitable model group for studies on the comparative influence of adaptive versus non-adaptive processes of species formation [ 43 ].…”

Evolution in the Genus Rhinella: A Total Evidence Phylogenetic Analysis of Neotropical True Toads (Anura: Bufonidae)

“…This kind of event involving deep mitochondrial divergence that implies past mitochondrial introgression from an unknown and not closely related species is uncommon in anurans. Historical interspecific introgressions events were reported in several groups of Anura: Ameerega (Dendrobatidae; Brown and Twomey, 2009); Anaxyrus, Bufo, and Bufotes (Bufonidae; Malmos et al, 2001;Yamazaki et al, 2008;Colliard et al, 2010;Dufresnes et al, 2019); Bombina (Bombinatoridae; Hofman and Szymura, 2007;De Cahsan et al, 2019); Dyscophus (Microhylidae; Orozco-terWengel et al, 2013); Hyla (Hylidae;Lamb and Avise, 1986;Bryson et al, 2010Bryson et al, , 2014Klymus et al, 2010); Mantella (Mantellidae; Crottini et al, 2019); Pelophylax and Rana (Ranidae; Liu et al, 2010;Zhou et al, 2012;Eto et al, 2013); Quasipaa (Dicroglossidae; Zhang et al, 2018); and Scutiger (Megophryidae; Chen et al, 2009). However, most of these events (except in Bombina, Bufotes, Quasipaa, and Scutiger) occurred among closely related species.…”

Are narrow-ranging species doomed to extinction? Projected dramatic decline in future climate suitability of two highly threatened species

“…In absence of information regarding the dispersal capacity of both species, we used two background corresponding to past dispersal hypotheses. The background covering the whole respective islands seems the most appropriate when assuming that only the sea could represent a dispersal barrier and that species could have dispersed throughout the whole island with regard to past climate and forest cover (Crottini et al 2019), as assumed in Fieldsend et al (2021). This might be the case for both species, especially P. inexpectata since the island is smaller and mostly occupied by a closely related species (P. borbonica; Dubos et al 2021a).…”

“…These were the Manapany day gecko Phelsuma inexpectata, classified as Critically Endangered (IUCN & MNHN, 2010) and the golden mantella frog Mantella aurantiaca formerly classified as Critically Endangered (Vences & Raxworthy, 2008), now classified as Endangered after the inclusion of one locality record which increased its extent of occurrence (IUCN SSC Amphibian Specialist Group 2020). Both species are in continued decline (Probst & Turpin, 1997;Crottini et al, 2019), live in highly fragmented areas (respectively in Reunion Island and central Madagascar) and are in urgent need for conservation actions. Given the important, long-term efforts invested to document their distribution, we assume that the geographic information for these species is nearly comprehensive and unbiased.…”