17-12-19, cross country à Antony (interclubs des White Harriers) Redinger, gagnant club Société Générale : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 57170

Les amants de la frontière : roman / Jules Mary

Collection : Le livre national ; n° 55-56

Les amants de la frontière : roman / Jules Mary

Collection : Le livre national ; n° 55-56

La goutte de sang.... La détresse d'une mère / Jules Mary

Collection : Le livre national ; n° 71-72

La goutte de sang.... Perdues dans Paris / Jules Mary

Collection : Le livre national ; n° 71-72

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.

La charmeuse d'enfants / Jules Mary

Collection : Le livre national ; n° 25

Le démon de l'amour / Jules Mary

Collection : Le livre national ; n° 26

Soldats de demain. Les filles du général / Jules Mary

Collection : Le livre national ; n° 217-218

Soldats de demain. La bataille d'avant la guerre / Jules Mary

Collection : Le livre national ; n° 217-218

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.

Carte statistique de la France électorale : (Chambre de 1839) / par A. Frère de Montizon ; Dédiée à M.Mrs les électeurs

Échelle(s) : [ca 1:2 145 000]