Spacing behavior and morphology predict promiscuous mating strategies in the rock-dwelling snow vole, Chionomys nivalis

Abstract

Adaptive models predict that variation in the spacing of microtines during reproductive periods may reflect mating strategies linked to differences in habitat characteristics. Using spatial and morphological analyses, we aimed to assess the mating system adopted by a population of rock-dwelling snow voles, Chionomys nivalis (Martins, 1842), and its functional significance within high-mountain environments. Spacing data coincided with a pattern generally associated with promiscuous mating: males had largely overlapping home ranges, whereas female home ranges showed a very reduced or absent degree of overlap. In addition, ranges overlapped considerably between sexes. Males had significantly greater body mass than females, and the magnitude of this difference resembled more a promiscuous than a polygamous or monogamous species. Also, relative testis size of males was in the range reported for promiscuous voles. Our results fit the predictions made by food abundance and distribution optimality models, suggesting that mating strategies might be related to the habitat occupied by C. nivalis. In alpine rocky formations, vegetation is sparse and patchily distributed, and competing females could benefit from defending an exclusive territory. In turn, males might be unable to monopolize widely spaced females by defending exclusive territories, which may result in extensive overlap between their spatial ranges. Résumé :Les modèles d'adaptation prédisent que la variation de l'espacement des microtinés durant la période de reproduction peut être reliée à des stratégies de reproduction associées aux différences de caractéristiques des habitats. Des analyses spatiales et morphologiques nous ont servi à évaluer le système d'accouplement adopté par une population de campagnols des neiges, Chionomys nivalis (Martins, 1842), et à faire des hypothèses sur son importance fonctionnelle dans les milieux de haute altitude. Les données sur l'espacement correspondent à un pattern généralement associé à un accouplement de promiscuité: les aires vitales des mâles se recoupent considérablement, alors que celles des femelles ont peu ou pas de recoupement. De plus, les aires vitales des deux sexes se chevauchent beaucoup. Les mâles ont une masse corporelle significativement plus grande que celle des femelles et l'importance de cette différence correspond plus à ce que l'on retrouve chez une espèce qui pratique la promiscuité plutôt que la polygamie. De plus, la taille relative des testicules des mâles se situe dans l'étendue des mesures signalées chez les espèces qui pratiquent la promiscuité. Nos résultats concordent avec les prédictions des modèles d'optimalité de l'abondance et de la réparti-tion de la nourriture, ce qui indique que les stratégies d'accouplement sont peut-être reliées à l'habitat occupé par C. nivalis. Comme la végétation dans les formations rocheuses alpines est éparse et répartie de façon contagieuse, les femelles tirent sans doute un bénéfice de la défense d'un territoire exclusif. D'autre part, si les mâles défendaient ...

Consequences of natal philopatry for reproductive success and mate choice in an Alpine rodent

“…During this period, females normally produce 1 or 2 litters of 1-5 pups (Janeau and Aulagnier 1997). Because of its low fertility, this species is typically considered a k-strategist (Nieder and Bocchini 1993;Luque-Larena et al 2004), which appears to be a common trait among petrophilic mammals (Mares and Lacher 1987). The average snow vole lifespan is 12-13 months, which means that most individuals do not survive the first winter (Janeau and Aulagnier 1997).…”

“…Mean relatedness among neighboring females was computed by averaging relatedness estimates for each focal female in relation to all adult females present within a 30-m radius. We chose 30 m as a cut-off because this distance has been reported to be the mean radius of the home range area in adult females (Luque-Larena et al 2004;Pérez-Aranda et al 2009). It is thought that males do not maintain territories but rather roam between several female territories (Luque-Larena et al 2004; Bonnet T, personal observation; see also Gauffre et al 2009).…”

Gene flow counteracts the effect of drift in a Swiss population of snow voles fluctuating in size

“…This habitat preference leads to highly isolated populations and a naturally fragmented distribution (Castiglia et al, 2009). The snow vole has a promiscuous mating system in which both males and females mate with multiple partners (Luque-Larena et al, 2004). Females show territorial behaviour but tolerate the presence of relatives; daughters usually remain in their natal area, resulting in matrilineal female clusters.…”

“…Females show territorial behaviour but tolerate the presence of relatives; daughters usually remain in their natal area, resulting in matrilineal female clusters. Males have overlapping home ranges, which can encompass the territories of several females (Luque-Larena et al, 2004). The reproductive period is from May to August, during which they produce one or two litters of one to five pups each (Janeau and Aulagnier, 1997).…”

Determinantes da sobreposição da área de vida no roedor Akodon montensis: implicações para os sistemas territoriais e de acasalamento

“…Nonetheless, previous studies on mammals focused mostly on a single population (e.g. Luque-Larena et al 2004, Asher et al 2008, Innes et al 2009, Hilgartner et al 2012, limiting the ability to encompass environmental and ecological variation and different individual strategies, and thus to detect transitions between territorial/mating systems (but see Eberle & Kappeler 2004). In this group, the transition from a polygynous mating system with territorial females to one with territorial males is expected to occur when resource availability increases and females, previously defending a territory, begin to tolerate home range overlap due to increasing defense costs.…”