Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Biological Journal of the Linnean Society 29-46 Africa biogeography cytogenetics desert morphology pleistocene rodent 2009 fdi:010046333 ENG Biological Journal of the Linnean Society 0024-4066 ISI:000269315600003 1 https://www.documentation.ird.fr/hor/fdi:010046333 https://www.documentation.ird.fr/intranet/publi/2009/09/010046333.pdf 98 Horizon (IRD) The present study aims to depict the overall pattern of Acomys history in south-western Sahara. We tested the specific predictions that: (1) several mitochondrial clades can be identified and that they coincide with the described species; (2) successive phases of desert expansion and contraction during the last 3 Myr have resulted in several phases of demographic expansion and population fragmentation in Acomys; and (3) isolation-by-distance occurs. The extent of phylogeographic patterns and molecular genetic diversity (cytochrome b gene and D-loop) were addressed in a survey of 90 individuals of Acomys from 38 localities. Our phylogeographical analyses show a strong genetic structure within western Saharan Acomys, with several phylogroups displaying non-overlapping geographic distributions. Restricted gene flow with isolation-by-distance was recorded and a signal of population expansion was detected within several clades. We suggest that during arid or semi-arid paleoclimatic periods, when large sandy areas were present, Acomys was restricted to rocky massifs, whereas, in more humid periods, when savannah and/or steppe habitat prevailed, this species was able to disperse and to survive outside rocky areas because food resources were abundant. Based on a comprehensive sampling and the use of an integrative approach (i.e. combining cytogenetic, molecular and morphological data), we firmly propose that Acomys airensis should be considered as a junior synonym of Acomys chudeaui. 040 UR022 Sénégal