Search

Ndiaye, A., Bâ, K., Aniskin, V., Benazzou, T., Chevret, P., Konecný, A., Sembene, M., Tatard, C., Kergoat, G.J. & Granjon, L. (2011). Evolutionary systematics and biogeography of endemic gerbils (Rodentia, Muridae) from Morocco: an integrative approach. —Zoologica Scripta, 41, 11–28. Gerbils of the genus Gerbillus represent an important part of small mammal diversity in arid regions of North Africa, but their taxonomy and evolutionary systematics and biogeography are still poorly known. Based on the recent collection of a series of gerbils in southern Morocco, including at the type localities of three endemic species, we gathered morphological, chromosomal and molecular data on a number of specimens that we compared with other available results. These data provide new insights into the geographical distribution of the endemic species known to date and suggest that an additional and previously undetected species may exist within this area. Multivariate analyses of morphometrical skull data validated the criteria used in the description of some of these species, while confirming the morphological similarity of a set of medium to large-sized species with hairy feet that can be considered sibling species. Karyotypes were useful for the specific assignation of a number of specimens. Molecular phylogenetics and divergence time estimates allow us to draw the first picture of the evolutionary relationships between endemic Gerbillus species from Morocco and related species of North Africa, and to estimate their respective timing of diversification. Most of the lineage emergence events took place during the Pleistocene, a period characterised by a global aridification of North Africa, but more importantly by important climatic and eustatic variations that may have played a role in species differentiation and subsequent expansion. This integrative approach proved to be essential in such species group including morphologically similar species. It also enables to propose testable hypotheses as to possible scenarios of emergence and evolution of these species along the western margin of the Sahara desert.

The Mediterranean Basin is an acknowledged hotspot for biodiversity, yet historical processes that shaped this biodiversity in North Africa remain poorly understood. This study aimed to elucidate the phylogeographic pattern of an endemic species of Mediterranean areas of North Africa, the Greater Egyptian Jerboa, Jaculus orientalis. The extent of phylogeographic patterns and molecular genetic diversity (mitochondrial cytochrome b gene) were addressed in a survey of 45 jerboas from 24 localities. Our phylogeographical analyses show a strong genetic subdivision into three areas along a west-east axis, corresponding to (1) Morocco and western Algeria; (2) eastern Algeria, Tunisia and western Libya; (3) eastern Libya and Egypt. Demographic analyses revealed different modalities of population expansion since the last glacial age depending on geographic areas. The dating using relaxed molecular clock analyses revealed that most splits occurred during the Quaternary (

E-mail Addresses: brouat@mpl.ird.fr; International audience; Aim : To investigate the phylogeographical structure of the Guinea multimammate mouse, Mastomys erythroleucus (Temminck, 1853), a widespread murid rodent in sub-Saharan (Sahel and Sudan) savannas, for a better understanding of the impacts of geographical and historical factors on the evolutionary history of this species, in the context of the growing database of phylogeographical studies of African savanna mammal species. Location Sahel and Sudan savannas, Africa. Methods : We sequenced the whole cytochrome b gene in 211 individuals from 59 localities distributed from Senegal to Ethiopia. Sequence data were analysed using both phylogenetic (several rooted tree-construction methods, median-joining networks) and population genetic methods (spatial analyses of molecular variance, mismatch distributions). Results : Haplotypes were distributed into four major monophyletic groups corresponding to distinct geographical regions across a west-east axis. Diversification events were estimated to have occurred between 1.16 and 0.18 Ma. Main conclusions : Vicariance events related to the fragmentation of savanna habitats during the Pleistocene era may explain the phylogeographical patterns observed. Genetic structure was consistent with a role of major Sahelian rivers as significant barriers to west-east dispersal. Recent demographic expansions probably occurred during arid phases of the Holocene with the southward expansion of savannas

The multimammate rat Mastomys huberti is a Sahelian species restricted to West Africa. Throughout its distribution area, the species is associated with humid habitats, flood plains and ponds, which make its current distribution highly fragmented. Knowing that humid and dry climatic phases regularly alternated along the Quaternary in West Africa, it can be postulated that the evolutionary history of the species and its genetic variation largely reflect these climatic oscillations. We used mitochondrial cytochrome b sequences to investigate the phylogenetic relationships of M. huberti populations across the totality of the species' geographical range (Mali, Senegal, Guinea and Mauritania). We found that cytochrome b sequence variation is partitioned into four divergent clades (mean Kimura 2-parameter genetic distances varying from 0.57 to 3.08%) corresponding to distinct geographical regions. We dated the separation events of these clades between 0.93 and 0.17 million years ago, suggesting that M. huberti history was strongly influenced by the Quaternary climatic variations and related hydrographic network changes. Relationships between lineages and the partitioning of genetic diversity suggest the occurrence of two refuges along the Atlantic coast during arid periods. Moreover, the species' current range results from a stepwise colonization from west to east. M. huberti colonized recently the Inner Delta of Niger River in Mali, probably during a humid episode some 0.6 million years ago. Demographically stable and highly diversified populations were found in South Senegal and Guinea while populations in North Senegal and in Mali experienced low numbers followed by a demographic expansion during the African Humid Period (c. 14 800-5500 bp). During the last arid period (c. 23 000-18 000 years ago), Malian populations found refuge in the northern parts of the Inner Delta of the Niger River, then expended to the southern parts of the delta and along the course of the Niger River downstream Tombouctou. More recently, M. huberti would have rapidly expanded into irrigated areas along the Senegal River and along the Canal du Sahel, Mali, reflecting the invasive and the pest character of this species.