Phylogeography of a Morphologically Cryptic Golden Mole Assemblage from South-Eastern Africa

Abstract

The Greater Maputaland-Pondoland-Albany (GMPA) region of southern Africa was recently designated as a centre of vertebrate endemism. The phylogeography of the vertebrate taxa occupying this region may provide insights into the evolution of faunal endemism in south-eastern Africa. Here we investigate the phylogeographic patterns of an understudied small mammal species assemblage (Amblysomus) endemic to the GMPA, to test for cryptic diversity within the genus, and to better understand diversification across the region. We sampled specimens from 50 sites across the distributional range of Amblysomus, with emphasis on the widespread A. hottentotus, to analyse geographic patterns of genetic diversity using mitochondrial DNA (mtDNA) and nuclear intron data. Molecular dating was used to elucidate the evolutionary and phylogeographic history of Amblysomus. Our phylogenetic reconstructions show that A. hottentotus comprises several distinct lineages, or evolutionarily significant units (ESUs), some with restricted geographic ranges and thus worthy of conservation attention. Divergence of the major lineages dated to the early Pliocene, with later radiations in the GMPA during the late-Pliocene to early-Pleistocene. Evolutionary diversification within Amblysomus may have been driven by uplift of the Great Escarpment c. 5–3 million years ago (Ma), habitat changes associated with intensification of the east-west rainfall gradient across South Africa and the influence of subsequent global climatic cycles. These drivers possibly facilitated geographic spread of ancestral lineages, local adaptation and vicariant isolation. Our study adds to growing empirical evidence identifying East and southern Africa as cradles of vertebrate diversity.

Environmental correlates of phylogenetic endemism in amphibians and the conservation of refugia in the Coastal Forests of Eastern Africa

“…Broad biogeographic breaks are common in many other vertebrate taxa across other parts of sub‐Saharan Africa including ungulates (Arctander, Johansen, & Coutellec‐Vreto, ; Lorenzen et al., ), small mammals (Mynhardt et al. ), birds (Habel et al., ) and reptiles (Tolley et al., ). This points towards the importance of refugia in the persistence of biodiversity during long‐term climate change (Fjeldså & Lovett, ).…”

“…We took the average of 25 model replicates for each SDM, evaluating model performance using the area under the curve (AUC) statistic. Models were corrected for overprediction using the minimum convex polygon method in SD Mtoolbox 1.1 c (Brown, Cameron, Yoder, & Vences, ) supplemented by our own knowledge of coastal forest amphibians and species range maps (IUCN, ). Each SDM was subsequently partitioned into its constituent LDMs using cost distances, jointly informed by the species ecological niche and known locations of each lineage based on geo‐referenced genetic data (Rosauer et al., ).…”

“…These measures are a useful proxy for historical climatic stability through deeper time (see Sandel et al, 2011) and can help to explain biogeographic breaks and endemism at the species level not only in many amphibians (e.g., Barratt et al, 2017;Loader et al, 2014;Zimkus et al, 2017) but also across other taxonomic groups. Broad biogeographic breaks are common in many other vertebrate taxa across other parts of sub-Saharan Africa including ungulates (Arctander, Johansen, & Coutellec-Vreto, 1999;Lorenzen et al, 2012), small mammals (Mynhardt et al 2015), birds (Habel et al, 2015) and reptiles (Tolley et al, 2011). This points towards the importance of refugia in the persistence of biodiversity during long-term climate change (Fjeldså & Lovett, 1997).…”

Pleistocene golden mole and sand-swimming trace fossils from the Cape coast of South Africa

“…Thus, as a family, golden moles display high rates of endemism. The relatively widespread ‘species’ Amblysomus hottentotus may in fact represent a species complex, containing distinct cryptic species that may be vulnerable (Mynhardt et al, 2015).…”

Mountains of the Mist: A first plant checklist for the Bvumba Mountains, Manica Highlands (Zimbabwe-Mozambique)

“…Southern African mountains continue to fascinate biologists, ecologists and conservationists with their high endemism, high species diversity, and as a haven for taxonomically complex and cryptic evolutionary lineages (White 1978;Taylor et al 2013;Uys and Cron 2013;Conradie 2014;Mynhardt et al 2015;Padayachee and Procheş 2016;Phiri and Daniels 2016;Conradie et al 2018;Branch et al 2019). From a floristic perspective, there has been a steady output of comprehensive data from the region over the past 25 years, for example the Nyika Plateau (Burrows and Willis 2005) and Mount Mulanje (Strugnell 2006) in Malawi; Mounts Gorongosa, Mabu and Namuli (Müller et al 2008;Timberlake et al 2009;Bayliss et al 2014;Timberlake, in prep.…”