Arame Ndiaye

Evolutionary systematics and biogeography of endemic gerbils (Rodentia, Muridae) from Morocco: an integrative approach

Ndiaye, A., Bâ, K., Aniskin, V., Benazzou, T., Chevret, P., Konečný, A., Sembène, 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.

Phylogeography of the North African dipodil (Rodentia: Muridae) based on cytochrome-b sequences

Abstract The present study aims to depict the overall pattern of the history of the North African dipodil, Gerbillus campestris, in the northern Sahara. More specifically we document whether or not Pleistocene refugia, the Sahara desert, and the Moulouya River structure patterns of diversity in this species. The phylogenetic relationships among populations were determined by analyses of the cytochrome-b gene in 100 specimens collected in 5 countries (Morocco, Algeria, Tunisia, Mali, and Niger) and 27 localities. Our study highlights a complex phylogeographic pattern for G. campestris in North Africa, with 9 phylogenetic lineages differing by up to 2.5% of sequence divergence. Most of these lineages are allopatric, except in Morocco where 2 lineages are overlapping in the south. These genetic lineages probably arose during the successive cycles of cooling and warming climatic conditions that characterized the end of the Pleistocene, caused by the combined effects of habitat changes and marine transgressions. The divergence between Saharan and Moroccan populations occurred during a period of aridification at the end of the Pleistocene. The Moulouya and the Bou Regreg rivers also seem to be major biogeographical barriers to gene flow in this species.

Molecular variation and chromosomal stability within Gerbillus nanus (Rodentia, Gerbillinae): taxonomic and biogeographic implications

Abstract The systematics of the rodent genus Gerbillus still needs clarifications. Within this genus, Gerbillus nanus is a species often considered to have a wide geographic distribution ranging from northwest India to the Mauritanian coast. Some authors, however, have suggested that other species, namely Gerbillus amoenus and/or Gerbillus garamantis, may replace G. nanus over a part of, or over the whole of its African area of occurrence. Here, we bring together new karyological data and molecular analyses of cytochrome b mitochondrial gene sequences of G. nanus specimens from various parts of the alleged extended distribution of the species: Pakistan and Israel in Asia, and Libya, Mali, and Mauritania in Africa. The karyotypes of Asian and African specimens appear similar, while a rather important genetic distance was found between samples of specimens from the two continents. This last finding suggests that at least two distinct species exist, G. nanus being the species of Asian distribution, and G. garamantis and/or G. amoenus being the one(s) with African distribution(s). Similar comparative analyses on larger samples are now needed to determine the precise taxonomic situation in this group, as well as the distribution limits of each species.

Repeated evolution of camouflage in speciose desert rodents

There are two main factors explaining variation among species and the evolution of characters along phylogeny: adaptive change, including phenotypic and genetic responses to selective pressures, and phylogenetic inertia, or the resemblance between species due to shared phylogenetic history. Phenotype-habitat colour match, a classic Darwinian example of the evolution of camouflage (crypsis), offers the opportunity to test the importance of historical versus ecological mechanisms in shaping phenotypes among phylogenetically closely related taxa. To assess it, we investigated fur (phenotypic data) and habitat (remote sensing data) colourations, along with phylogenetic information, in the species-rich Gerbillus genus. Overall, we found a strong phenotype-habitat match, once the phylogenetic signal is taken into account. We found that camouflage has been acquired and lost repeatedly in the course of the evolutionary history of Gerbillus. Our results suggest that fur colouration and its covariation with habitat is a relatively labile character in mammals, potentially responding quickly to selection. Relatively unconstrained and substantial genetic basis, as well as structural and functional independence from other fitness traits of mammalian colouration might be responsible for that observation.

Lipid profile frequency and the prevalence of dyslipidaemia from biochemical tests at Saint Louis University Hospital in Senegal

Introduction The aim of this study was to evaluate the frequency of lipid profile requests and the prevalence of dyslipidemia in patients at the biochemistry laboratory of St. Louis University Hospital, as well as their correlation with sex and age. Methods This was a retrospective study reviewing 14,116 laboratory results of patients of both sexes, over a period of six months (January-June 2013) regardless of the indication for the request. The lipid parameters included were: Total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides with normal values defined as follows: Total cholesterol (<2g/l), HDL- cholesterol (>0,40g/l), LDL- cholesterol (<1,30g/l) and Triglycerides (<1,50g/l). Results The average age of our study population was 55.15 years with a female predorminance (M/F = 0.60). The age group most represented was that between 55-64 years. The frequency of lipid profile request in our sample was 9.41% (or 1,329). The overall prevalence of isolated hypercholesterolemia, hyperLDLaemia, hypoHDLaemia, hypertriglyceridaemia, and mixed hyperlipidemia were respectively 60.91%, 66.27%, 26.58%, 4.57% and 2.75%. Hypercholesterolemia, hyperLDLaemia, hypertriglyceridaemia and mixed hyperlipidaemia were higher in women with respectively 66.22%, 67.98%, 4.58%, 2.89% than in men (52.01%, 62.81%, 4.44% and 2.40% respectively). On the other hand, the prevalence of hypoHDLaemia was higher in males (32.19%) compared to females (23.76%). Hypercholesterolemia correlated significantly with age and sex. Conclusion Our study showed a relatively low request rate for lipid profile and a high prevalence of dyslipidaemia hence the importance of conducting a major study on the prevalence of dyslipidaemia and associated factors in the Senegalese population.

Profil biochimique et hématologique des patients drépanocytaires homozygotes en phase stationnaire au centre National de Transfusion Sanguine de Dakar

La drepanocytose est caracterisee par une grande variabilite d’expression clinique et biologique qui depend de plusieurs facteurs. L’objectif de ce travail etait d’etudier les perturbations biologiques des patients drepanocytaires homozygotes en phase stationnaire. Il s’agit d’une etude prospective transversale ayant inclus 100 drepanocytaires homozygotes en phase stationnaire d’âge superieur a 15 ans. Chaque patient a beneficie de deux tubes de prelevements pour l’etude des parametres hematologiques et pour les dosages biochimiques. Un questionnaire a ete utilise pour recueillir les variables epidemiologiques, cliniques et biologiques. Ces donnees ont ete saisies et analysees par le logiciel Epi-info 7.2. Une valeur p ≤ 0,05 a ete consideree comme significative. L’âge moyen des patients etait de (28 ± 8,94) ans, les extremes (15-57 ans) et le sex-ratio (H/F) de 0,75. Le taux d’hemoglobine de base etait en moyenne de (8,2 ± 1,4g/dl), les globules blancs de (12352 ± 6.906/ mm 3 ), les plaquettes (439.920 ± 139.000/mm 3 ), la TCMH (31,18pg ± 4,12 pg). Le taux d’hemoglobine S etait en moyenne de (87,79 ± 8,19 %) et l’hemoglobine F (HbF) (9,5 ± 8,3%). Le taux HbF etait associee de facon significative avec le syndrome thoracique aigu et la lithiase biliaire (r=0,56 ; p=0,003). Cette etude a montre que les perturbations biologiques sont frequentes chez les dans la drepanocytaires homozygotes. Leur connaissance servira de base de comparaison lors des crises et pour evaluer l’efficacite du traitement.