Phylogeography of a widespread sub-Saharan murid rodent Aethomys chrysophilus: the role of geographic barriers and paleoclimate in the Zambezian bioregion

Murid rodents of the genus Aethomys are one of the most common rodents in drier habitats in sub-Saharan Africa. Among them, the red veld rat Aethomys chrysophilus is the most widespread species with the core distribution located in the Zambezian bioregion. In this study, we describe phylogeographic structure of the species and estimate its age from a time-calibrated phylogeny of the genus. Seven parapatric clades were identified in the mitochondrial cytochrome b phylogeny, where some of the distributions of these clades have been separated by previously described biogeographical divides (Zambezi-Kafue river system, Rukwa Rift and the Eastern Arc Mountains). One internal clade corresponded to populations previously described as a distinct species, Aethomys ineptus. The whole A. chrysophilus complex was estimated to be 1.3 (0.5–2.4) Mya old, with A. ineptus originating 0.7 (0.1–1.4) Mya before present. The internal position of A. ineptus was also recovered in phylogenetic reconstruction based on two nuclear genes and thus it is not a consequence of mitochondrial introgression. In addition, we analyzed skull form variation across the species’ distributional range and found no significant difference between A. ineptus and the rest of A. chrysophilus complex

Bite force in the strictly subterranean rodent family of African mole-rats (Bathyergidae) : the role of digging mode, social organization and ecology

DATA AVAILABILITY STATEMENT : The data are deposited in the Dryad Digital Repository https://datadryad.org/stash/dataset/doi:10.5061/dryad.ksn02v772 (Kraus et al., 2022).Bite force is an ecologically relevant performance trait that has been measured to better understand the adaptations to diet and habitat use. Moreover, bite force is relevant in understanding reproductive success, as well as inter- and intraspecific competition. African mole-rats (Bathyergidae, Rodentia) are a unique clade of mammals that use different digging strategies, show different types of social organization and occur in ecologically diverse savanna habitats in sub-Saharan Africa. Whereas previous studies have suggested these animals have exceptionally high bite forces, the ecological and other proximate and ultimate drivers of variation in bite force in the group remain unstudied. In the present study we measured in vivo bite force of 394 adult specimens from 10 African mole-rat species including all genera within the family. Our results show that in African mole-rats digging mode is a major driver of variation in bite force, with chisel-tooth diggers being stronger biters than scratch diggers. Moreover, species living in habitats characterized by low and irregular precipitation patterns and in soils with a high content of coarse particles have a higher bite force than species occupying habitats with a regular rainfall pattern and fine soil types. This suggests that bite force in bathyergids has evolved in concert with rainfall and soil characteristics of different savanna habitats, which have contributed to the successful radiation of these subterranean mammals across sub-Saharan Africa.Czech Science Foundation.http://www.wileyonlinelibrary.com/journal/fec2023-07-02hj2023Mammal Research InstituteZoology and Entomolog

Evolutionary history and species diversity of African pouched mice (Rodentia: Nesomyidae: Saccostomus)

Zoologica Scripta, 2016We explore diversity of African pouched mice, genus Saccostomus (Rodentia, Nesomyidae), by sampling molecular and morphological variation across their continental-scale distribution in southern and eastern African savannahs and woodlands. Both mitochondrial (cytochrome b) and nuclear DNA (IRBP, RAG1) as well as skull morphology confirm the distinction between two recognized species, S. campestris and S. mearnsi, with disjunct distribution in the Zambezian and Somali–Maasai bioregions, respectively. Molecular dating suggests the divergence of these taxa occurred in the Early Pliocene, 3.9 Ma before present, whereas the deepest divergences within each of them are only as old as 2.0 Ma for S. mearnsi and 1.4 Ma for S. campestris. Based on cytochrome b phylogeny, we defined five clades (three within S. campestris, two in S. mearnsi) whose species status was considered in the light of nuclear DNA markers and morphology. We conclude that S. campestris group consists of two subspecies S. campestris campestris (Peters, 1846; comprising two cytochrome b clades) and S. campestris mashonae (de Winton, 1897) that are moderately differentiated, albeit distinct in IRBP and skull form. They likely hybridize to a limited extent along the Kafue–Zambezi Rivers. Saccostomus mearnsi group consists of two species, S. mearnsi (Heller, 1910) and S. umbriventer (Miller, 1910), that are markedly differentiated in both nuclear markers and skull form and may possibly co-occur in south-western Kenya and north-eastern Tanzania. Analysis of historical demography suggests both subspecies of S. campestris experienced population expansion dated to the Last Glacial. In the present range of S. campestris group, the distribution modelling suggests a moderate fragmentation of suitable habitats during the last glacial cycle, whereas in the range of S. mearnsi group it predicts substantial shifts of its occurrence in the same period

Evolutionary history and species diversity of African pouched mice (Rodentia: Nesomyidae: Saccostomus)

Zoologica Scripta, 2016We explore diversity of African pouched mice, genus Saccostomus (Rodentia, Nesomyidae), by sampling molecular and morphological variation across their continental-scale distribution in southern and eastern African savannahs and woodlands. Both mitochondrial (cytochrome b) and nuclear DNA (IRBP, RAG1) as well as skull morphology confirm the distinction between two recognized species, S. campestris and S. mearnsi, with disjunct distribution in the Zambezian and Somali–Maasai bioregions, respectively. Molecular dating suggests the divergence of these taxa occurred in the Early Pliocene, 3.9 Ma before present, whereas the deepest divergences within each of them are only as old as 2.0 Ma for S. mearnsi and 1.4 Ma for S. campestris. Based on cytochrome b phylogeny, we defined five clades (three within S. campestris, two in S. mearnsi) whose species status was considered in the light of nuclear DNA markers and morphology. We conclude that S. campestris group consists of two subspecies S. campestris campestris (Peters, 1846; comprising two cytochrome b clades) and S. campestris mashonae (de Winton, 1897) that are moderately differentiated, albeit distinct in IRBP and skull form. They likely hybridize to a limited extent along the Kafue–Zambezi Rivers. Saccostomus mearnsi group consists of two species, S. mearnsi (Heller, 1910) and S. umbriventer (Miller, 1910), that are markedly differentiated in both nuclear markers and skull form and may possibly co-occur in south-western Kenya and north-eastern Tanzania. Analysis of historical demography suggests both subspecies of S. campestris experienced population expansion dated to the Last Glacial. In the present range of S. campestris group, the distribution modelling suggests a moderate fragmentation of suitable habitats during the last glacial cycle, whereas in the range of S. mearnsi group it predicts substantial shifts of its occurrence in the same period

Nuclear phylogenomics, but not mitogenomics, resolves the most successful Late Miocene radiation of African mammals (Rodentia: Muridae: Arvicanthini)

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