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Unveiling the demographic history of three Malagasy amphibian species using ddRAD sequencing
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Resumo(s)
Madagascar is one of the largest islands in the world, hosting almost unparalleled levels of species
richness and endemism. Its unique biodiversity is threatened by multiple factors (e.g.
deforestation, overexploitation and invasive species), making it a critical priority region for
international conservation efforts.
In this study, we applied a double digest Rad sequencing (ddRADseq) approach to infer the
demographic history and evolution of the effective population size (Ne) of three amphibian
species - Ptychadena mascareniensis, Boophis obscurus and Mantidactylus bourgati - which cooccur in the region of the Andringitra Massif, in southeastern Madagascar. These species differ
strongly in their distributional range sizes (from widespread throughout the country, to endemic
to a portion of Madagascar, or microendemic to the Andringitra region, respectively).
Since RAD-seq methods allow to produce cost-effective and informative representations of a
species genome and do not necessarily require a reference genome to perform efficiently, they
are suitable for studying non-model organisms. Therefore, we applied a ddRADseq approach to
obtain genomic data for these target species and inferred past demographic trends, such as
possible populations contractions, expansions and/or bottlenecks, and related them to the history
of events that characterized the area surrounding our sampling sites.
Our findings suggest that the Ne of Boophis obscurus and Mantidactylus bourgati have sharply
decreased during a time period compatible with human expansion in Madagascar, possibly due to
the reduction, fragmentation, or degradation of their suitable habitats. In contrast, Ptychadena
mascareniensis experienced an increase in Ne during a similar timeframe, likely due to the
expansion of open areas conducive to its habitat preferences.
This study aimed to contribute to the conservation of these species by understanding their recent
past demographic responses to past pressures, providing an idea of their potential reactions to
future changes, and suggesting conservation strategies specifically tailored to their ecological
needs.
Descrição
Tese de mestrado, Biologia da Conservação, 2025, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Anfíbios Expansão humana ddRAD História demográfica Conservação Teses de mestrado - 2025