Use of phylogeny to resolve the taxonomy of the widespread and highly polymorphic African giant shrews (Crocidura olivieri group, Crocidurinae, Mammalia).

The aim of this study is to provide a better understanding of the genetic relationships within the widespread and highly polymorphic group of African giant shrews (Crocidura olivieri group). We sequenced 769 base pairs (bp) of the mitochondrial cytochrome b gene and 472 bp of the mitochondrial control region over the entire geographic range from South Africa to Morocco. The analyses reveal four main clades associated with different biomes. The largest clade occurs over a range covering Northwest and Central Africa and includes samples of C. fulvastra, C. olivieri, and C. viaria. The second clade is composed of C. goliath from Gabon, while South African C. flavescens, and C. hirta form two additional clades. On the basis of these results, the validity of some taxa in the C. olivieri group should be re-evaluated.

Habitat, morphology and karyotype of the Saharan shrew Crocidura tarfayaensis (Mammalia : Soricidae)

The Saharan shrew Crocidura tarfayaensis Vesmanis and Vesmanis, 1980, has a limited disribution along the Atlantic coast of Sahara, south of Agadir (Morocco) through Western Sahara into Mauritania and is only known from few captures and some owl pellets. Here we report field data from the successful trapping of five specimens of C. tarfayaensis in the Guelmim region. The habitat was characterized by sand dunes along a river, with dense shrubberies of Tamarix sp., the huge grass Erianthus ravennae (Poaceae) and flat bushes of Atriplex glauca var. ifniensis (Chenopodiaceae). Morphological discrimination with C. whitakeri were examined. The chromosomes of C. tarfayaensis revealed a karyotype of 2n = 36, similar to that of the Canary shrew C. canariensis and the Sicilian shrew C. sicula. In conclusion, C. tarfayaensis seems to be a descendant of the presumed continental ancestor of the two island species.

Disentangling reasons for low Y chromosome variation in the greater white-toothed shrew (Crocidura russula).

Y chromosome variation is determined by several confounding factors including mutation rate, effective population size, demography, and selection. Disentangling these factors is essential to better understand the evolutionary properties of the Y chromosome. We analyzed genetic variation on the Y chromosome, X chromosome, and mtDNA of the greater white-toothed shrew, a species with low variance in male reproductive success and limited sex-biased dispersal, which enables us to control to some extent for life-history effects. We also compared ancestral (Moroccan) to derived (European) populations to investigate the role of demographic history in determining Y variation. Recent colonization of Europe by a small number of founders (combined with low mutation rates) is largely responsible for low diversity observed on the European Y and X chromosomes compared to mtDNA. After accounting for mutation rate, copy number, and demography, the Y chromosome still displays a deficit in variation relative to the X in both populations. This is possibly influenced by directional selection, but the slightly higher variance in male reproductive success is also likely to play a role, even though the difference is small compared to that in highly polygynous species. This study illustrates that demography and life-history effects should be scrutinized before inferring strong selective pressure as a reason for low diversity on the Y chromosome.

Range expansion of the greater white-toothed shrew Crocidura russula in Switzerland results in local extinction of the bicoloured white-toothed shrew C-leucodon

The distribution limits of Crocidura russula (Hermann, 1780) and C. leucodon (Hermann, 1780) were investigated during an interval of 25 years in the bottom of the Rhone valley above Lake Geneva, Switzerland (total data set: 105 spatio-temporal occurrences, 1137 shrews). In 1975, the contact zone between the two species was situated in the region of Martigny. In 1999/2000, new sampling revealed three results: (1) The contact zone showed an upward shift of about 25 km. (2) In the expanded range of C. russula, the resident species has totally disappeared (confirmed by owl pellets analysis). (3) This demonstrates a dominance of C, russula over C. leucodon. Three hypotheses which may explain the range expansion of C. russula were evaluated: (1) habitat modification favouring linear dispersal due to the construction of a highway; (2) temporal event favoured by climate fluctuations, or (3) ongoing postglacial colonisation of Europe. Hypothesis 1 was rejected, because the progression of the shrews anticipated the construction. Hypothesis 3 received only weak support because range limits of C. russula in the region of Nice have been stable for thousands of years. Therefore hypothesis 2, admitting that ongoing climate change has facilitated range expansion, is the most probable.

Cytogenetic and molecular relationships between Zarudny's rock shrew (Crocidura zarudnyi; Mammalia : Soricomorpha) and Eurasian taxa

We karyotyped and sequenced 1,140 base pairs of the mitochondrial DNA cytochrome b of a specimen of Zarudny's rock shrew (Crocidura zarudnyi) from Baluchestan, southeastern Iran, to clarify its cytogenetic and molecular relationships with other Eurasian species of Crocidura. According to the karyotype (2N = 40, FN = 50), Zarudny's rock shrew belongs to the group of the lesser white-toothed shrew (C. suaveolens), which is different from other known crocidurine karyotypes, considering the combination of the diploid and fundamental number of chromosomes. Molecular results revealed that C. zarudnyi is included in a monophyletic clade with the C. suaveolens group, where it is a sister taxon to the others (mean Kimura 2-parameter distance = 9.7%).

Assessment of terrestrial small mammals and a record of the critically endangered shrew Crocidura wimmeri in Banco National Park (Cote d'Ivoire)

This study investigated the small mammal community of the periurban Banco National Park (34 km(2)), Abidjan, Cote d'Ivoire, using identical numbers of Sherman and Longworth traps. We aimed to determine the diversity and distribution of rodents and shrews in three different habitats: primary forest, secondary forest and swamp. Using 5014 trap-nights, 91 individuals were captured that comprised seven rodent and four shrew species. The trapping success was significantly different for each species, i.e., the Longworth traps captured more soricids (31/36 shrews), whereas the Sherman traps captured more murids (37/55 mice). The most frequent species was Praomys cf. rostratus, followed by Crocidura buettikoferi, Hybomys trivirgatus and Crocidura jouvenetae. Indices of species richness (S) and diversity (H') were greatest in primary forest, followed by secondary forest and swamp. - Several expected species, such as Crocidura obscurior, were not found, whereas we captured four specimens of the critically endangered (IUCN 2012) Wimmer's shrew Crocidura wimmeri, a species that has vanished from its type locality, Adiopodoume. Therefore, Banco National Park represents an important sanctuary, not only for plants, birds and primates, but also for other small forest vertebrates.

Individual reproductive success and effective population size in the greater white-toothed shrew Crocidura russula.

In order to investigate the determinants of effective population size in the socially monogamous Crocidura russula, the reproductive output of 44 individuals was estimated through genetic assignment methods. The individual variance in breeding success turned out to be surprisingly high, mostly because the males were markedly less monogamous than expected from previous behavioural data. Males paired simultaneously with up to four females and polygynous males had significantly more offspring than monogamous ones. The variance in female reproductive success also exceeded that of a Poisson distribution (though to a lesser extent), partly because females paired with multiply mated males weaned significantly more offspring. Polyandry also occurred occasionally, but only sequentially (i.e. without multiple paternity of litters). Estimates of the effective to census size ratio were ca. 0.60, which excluded the mating system as a potential explanation for the high genetic variance found in this shrew's populations. Our data suggest that gene flow from the neighbourhood (up to one-third of the total recruitment) is the most likely cause of the high levels of genetic diversity observed in this shrew's subpopulations.

Nonshivering thermogenesis capacity associated to mitochondrial DNA haplotypes and gender in the greater white-toothed shrew, Crocidura russula.

A selection gradient was recently suggested as one possible cause for a clinal distribution of mitochondrial DNA (mtDNA) haplotypes along an altitudinal transect in the greater white-toothed shrew, Crocidura russula (Ehinger et al. 2002). One mtDNA haplotype (H1) rare in lowland, became widespread when approaching the altitudinal margin of the distribution. As H1 differs from the main lowland haplotype by several nonsynonymous mutations (including on ATP6), and as mitochondria play a crucial role in metabolism and thermogenesis, distribution patterns might stem from differences in the thermogenic capacity of different mtDNA haplotypes. In order to test this hypothesis, we measured the nonshivering thermogenesis (NST) associated with different mtDNA haplotypes. Sixty-two shrews, half of which had the H1 haplotype, were acclimated in November at semioutdoor conditions and measured for NST throughout winter. Our results showed the crucial role of NST for winter survival in C. russula. The individuals that survived winter displayed a higher significant increase in NST during acclimation, associated with a significant gain in body mass, presumably from brown fat accumulation. The NST capacity (ratio of NST to basal metabolic rate) was exceptionally high for such a small species. NST was significantly affected by a gender x haplotype interaction after winter-acclimation: females bearing the H1 haplotype displayed a better thermogenesis at the onset of the breeding season, while the reverse was true for males. Altogether, our results suggest a sexually antagonistic cyto-nuclear selection on thermogenesis.

Vocalization of the shrew Suncus etruscus and Crocidura during normothermia and torpor

The vocalization of the shrews Suncus etruscus and Crocidura russula during normothermia and torpor is investigated. While frequency and call duration are independent of body temperature, the tremolo structure shows a spreading correlated with falling body temperature. The particular calls emitted during torpor are defence calls, modified by merely physiological factors. Their main function might be of intraspecific nature

Pliocene and Pleistocene diversification and multiple refugia in a Eurasian shrew (Crocidura suaveolens group).

We sequenced 998 base pairs (bp) of mitochondrial DNA cytochrome b and 799 bp of nuclear gene BRCA1 in the Lesser white-toothed shrew (Crocidura suaveolens group) over its geographic range from Portugal to Japan. The aims of the study were to identify the main clades within the group and respective refugia resulting from Pleistocene glaciations. Analyses revealed the Asian lesser white-toothed shrew (C. shantungensis) as the basal clade, followed by a major branch of C. suaveolens, subdivided sensu stricto into six clades, which split-up in the Upper Pliocene and Lower Pleistocene (1.9-0.9 Myr). The largest clade, occurring over a huge range from east Europe to Mongolia, shows evidence of population expansion after a bottleneck. West European clades originated from Iberian and Italo-Balkanic refugia. In the Near East, three clades evolved in an apparent hotspot of refugia (west Turkey, south-west and south-east of the Caucasus). Most clades include specimens of different morphotypes and the validity of many taxa in the C. suaveolens group has to be re-evaluated.

Social organization and mating system of free-ranging, greater white-toothed shrews, Crocidura russula

Indirect evidence from trapping suggests that Crocidura russula is less solitary and territorial than other shrews. To study the social organization and mating system, free-ranging adult and juvenile C. russula were tracked simultaneously throughout the year using a radioactive tracking technique. Coincident rest, coincident activity and home range overlap were measured. During winter, all individuals used the same communal nest and spent on average 84% of their total rest in coincident rest. This led to a large home range overlap (52% on average). Coincident activity was low (2% on average). At the onset of the reproductive season the females became, territorial and shared their nest with only one male. During pair formation, coincident activity and home range overlap were significantly greater between than within sexes. The social organization of C. russula appeared to be strongly influenced by season and differed in this respect from the other species in the genus Sorex which are territorial throughout the year.

Réponses de la musaraigne musette Crocidura russula, aux marquages odorants d'individus de son espèce (Insectivota, Soricidae)

In order to evaluate the reaction to conspecifics scent tracks of Crocidura russula, a shrew with poorly developped territorial behaviour, simple choice tests in a Y-shaped systems were used. C. russula prefers a marked path to an unmarked one, the tracks of an unknown individual to its own, the tracks of an individual of the opposite sex to those of an individual of the same sex, and the tracks of its sexual partner to those of another individual of the same sex. The choices between two tracks gave a less obvious result than the choices between a marked path and an unmarked one. Ecological and social implications of these results are discussed.

Inbreeding in the greater white-toothed shrew, Crocidura russula.

We combined mark-and-recapture studies with genetic techniques of parentage assignment to evaluate the interactions between mating, dispersal, and inbreeding, in a free-ranging population of Crocidura russula. We found a pattern of limited and female-biased dispersal, followed by random mating within individual neighborhoods. This results in significant inbreeding at the population level: mating among relatives occurs more often than random, and F(IT) analyses reveal significant deficits in heterozygotes. However, related mating partners were not less fecund, and inbred offspring had no lower lifetime reproductive output. Power analyses show these negative results to be quite robust. Absence of phenotypic evidence of inbreeding depression might result from a history of purging: local populations are small and undergo disequilibrium gene dynamics. Dispersal is likely caused by local saturation and (re)colonization of empty breeding sites, rather than inbreeding avoidance.

Breeding system and genetic variance in the monogamous, semi-social shrew, Crocidura russula

The population-genetic consequences of monogamy and male philopatry (a rare breeding system in mammals) were investigated using microsatellite markers in the semisocial and anthropophilic shrew Crocidura russula. A hierarchical sampling design over a 16-km geographical transect revealed a large genetic diversity (h = 0.813) with significant differentiation among subpopulations (F-ST = 5-6%), which suggests an exchange of 4.4 migrants per generation. Demic effective-size estimates were very high, due both to this limited gene inflow and to the inner structure of subpopulations. These were made of 13-20 smaller units (breeding groups), comprising an estimate of four breeding pairs each. Members of the same breeding groups displayed significant coancestries (F-LS = 9-10%), which was essentially due to strong male kinship: syntopic males were on average related at the half-sib level. Female dispersal among breeding groups was not complete (similar to 39%), and insufficient to prevent inbreeding. From our results, the breeding strategy of C. russula seems less efficient than classical mammalian systems (polygyny and male dispersal) in disentangling coancestry from inbreeding, but more so in retaining genetic variance.

The karyotype of Crocidura flavescens (Mammalia, Insectivora) in South Africa

Karyological results give evidence that the South African Crocidura flavescens (Geoffroy, 1827) is not conspecific with the West and East African giant shrews of the taxa spurrelli, manni, kivu and olivieri