Jerboas belonging to the genus Jaculus are widely distributed rodents inhabiting Palearctic desert and semi-desert areas. Previous studies on the lesser Egyptian jerboa Jaculus jaculus showed the existence of various morphological forms of controversial taxonomic status. They were sometimes related to two different species, J. jaculus and Jaculus deserti, although this has not been recognized in recent taxonomic updates. To clarify the systematic status of J. jaculus in Tunisia, we performed molecular (phylogenetic analyses of cytochrome b sequences), morphological (multivariate analyses of 13 skull measurements) and karyotypic (standard preparations from bone marrow cells) analyses on a number of specimens collected from ten localities. Our analyses revealed two monophyletic, well differentiated clades, with a mean genetic divergence value (K2P = 10.9 ± 0.01%), which is within the range of distances generally observed between rodent species. Morphometric analyses clearly separated populations of the two genetic clades from each other. However, karyotypes of individuals from both clades appeared similar. Individuals from both molecular clades/morphometric groups were found in sympatry in most of the localities sampled. These results, as obtained from a restricted area of the total distribution, suggest that there are two separate species within the currently accepted J. jaculus in Tunisia. Alternative hypotheses such as the occurrence of a strong, ancient phylogeographic structure, or the presence of pseudogenes, are also considered to account for the results obtained.

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 (<1 million of years ago). Finally, we discussed the relative roles of geological and climatic change in generating this pattern of genetic structure observed for the Greater Egyptian Jerboa and other vegetal and animal species in North Africa.

GRANJON L. 2010. Karyotypic variation in two species of jerboas Jaculus jaculus and Jaculus orientalis (Rodentia, Dipodidae) from Tunisia. Folia biol. (Kraków) #&: 229-236. The karyotypes of the lesser Egyptian jerboa Jaculus jaculus and the greater Egyptian jerboa Jaculus orientalis from Tunisia are described and compared with available data particularly from Egypt. The species examined have a similar karyotype consisting of 2n = 48 chromosomes and a fundamental number of autosomes (NFa) varying from 88 to 90 in J. jaculus and from 84 to 88 in J. orientalis. The X chromosome is submetacentric in both species, while the Y is submetacentric in J. orientalis and acrocentric in J. jaculus. Most of the autosomes are meta/submetacentric but the small pairs 22 -23 in J. jaculus and 20-23 in J.orientalis are frequently acrocentric, yielding considerable differences in the NFa within and among species. Morphological variation in these small pairs of autosomes and/or in the Y chromosome in J. orientalis may distinguish populations of the two species from Egypt and Tunisia. The differences observed either between Egypt and Tunisia or between the Tunisian Jaculus species are probably associated with chromosomal rearrangements such as pericentric inversions or heterochromatin variation. They appear of lesser magnitude than other changes (especially molecular) that have occurred during the evolution of this genus.

The lesser Egyptian jerboa Jaculus jaculus, is a member of the subfamily Dipodinae, known to have a number of subspecies. Previous studies of J. jaculus from North Africa found various morphological forms of unknown taxonomic status, which are frequently grouped into two taxa: J. jaculus and J. deserti. We assessed the taxonomic status of this taxon in Tunisia using allozymic (phylogenetic analysis of 23 genetic loci encoding 16 enzymatic proteins) and morphological (multivariate analysis of 13 craniodental characters) analyses of 136 J. jaculus specimens collected from seven localities within its distribution range. Allozymic analysis clearly indicated the existence of two distinct groups of J. jaculus, with a mean genetic distance (D) value of 0.99 and FST=0.52. Individuals within the two groups did not show any obvious geographical structuration, even within the Matmata locality which represents the meeting point for the two groups where they were found in sympatry. Additionally, morphometric analysis of 13 craniodental characters was clearly separated the two groups. These results were obtained over a very restricted area of the total distribution of J. jaculus and strongly suggest the occurrence of two separate and often sympatric species within the currently accepted J. jaculus in Tunisia: J. jaculus and J. deserti .

No abstract