Focusing on extraordinary organisms that are unique, or restricted to a particular area is always exciting, but sometimes even the seemingly ordinary can reveal fascinating insights into the historical biogeographic processes that have shaped the patterns of biodiversity we see today. Fairly common species found across a large area can tell us quite a lot about the effects of climate and evolution over time, especially those that have diversifed from a common ancestor into a complex of several related (but evolutionarily distinct) lineages or even species.
The Mascarene ridged frog Ptychadena mascareniensis is such an example, occuring across mainland and island areas of Africa mainly in savannah and open forest habitats and containing a number of divergent lineages with undescribed species diversity. Take a look at this new paper which investigates the evolutionary diversification of the P. mascareniensis species complex across its range and demonstrates how climatic niche evolution may have shaped current species diversity and distributions.
Fig. 1. Graphical abstract of the paper showing phylogenetic relationships, historical biogeography based on ancestral state reconstructions and bioclimatic niche of the P. mascareniensis complex.
Analyses within the paper show that there are at least ten distinct lineages of this species across Africa (7 in Africa, 3 on Madagascar, see Fig. 1) as a result of several speciation events mainly in the Miocene (over the past ~23 million years). Central Africa is identified as a diversity hotspot for these frogs with ‘out of Africa’ dispersal events to São Tomé in the west and Madagascar in the east. The P. mascareniensis from Tanzania where I focus my research appears to be the origin for the Madagascan radiation. The niches of these lineages are broadly similar in central Africa, with most tolerating similar climatic conditions (niche conservatism) but the lineages in West Africa and Madagascar exhibit very different ecological niches (niche divergence). The article is currently in press in Molecular Phylogenetics and Evolution.