Ice-Age Climate Adaptations Trap the Alpine Marmot in a State of Low Genetic Diversity.

Some species responded successfully to prehistoric changes in climate [1, 2], while others failed to adapt and became extinct [3]. The factors that determine successful climate adaptation remain poorly understood. We constructed a reference genome and studied physiological adaptations in the Alpine marmot (Marmota marmota), a large ground-dwelling squirrel exquisitely adapted to the "ice-age" climate of the Pleistocene steppe [4, 5]. Since the disappearance of this habitat, the rodent persists in large numbers in the high-altitude Alpine meadow [6, 7]. Genome and metabolome showed evidence of adaptation consistent with cold climate, affecting white adipose tissue. Conversely, however, we found that the Alpine marmot has levels of genetic variation that are among the lowest for mammals, such that deleterious mutations are less effectively purged. Our data rule out typical explanations for low diversity, such as high levels of consanguineous mating, or a very recent bottleneck. Instead, ancient demographic reconstruction revealed that genetic diversity was lost during the climate shifts of the Pleistocene and has not recovered, despite the current high population size. We attribute this slow recovery to the marmot's adaptive life history. The case of the Alpine marmot reveals a complicated relationship between climatic changes, genetic diversity, and conservation status. It shows that species of extremely low genetic diversity can be very successful and persist over thousands of years, but also that climate-adapted life history can trap a species in a persistent state of low genetic diversity.This work was supported by the Francis Crick Institute which receives its core funding from Cancer Research UK (FC001134), the UK Medical Research Council (FC001134), and the Wellcome Trust (FC001134). CB and AC are supported by the Agence Nationale de la Recherche (project ANR-13-JSV7-0005) and the Centre National de la Recherche Scientifique (CNRS), CB is supported by the Rhône-Alpes region (Grant 15.005146.01). LD is supported by Agence Nationale de la Recherche (project ANR-12-ADAP-0009). TIG is supported by a Leverhulme Early Career Fellowship (Grant ECF-2015-453) and a NERC grant (NE/N013832/1). JMG is supported by a Hertha Finberg Fellowship (FWF T703). LDR is supported by the Diabetes UK RD Lawrence Fellowship (16/0005382)

Sociality, mating system and reproductive skew in marmots: evidence and hypotheses

International audienceMarmot species exhibit a great diversity of social structure, mating systems and reproductive skew. In particular, among the social species (i.e. all except Marmota monax), the yellow-bellied marmot appears quite different from the others. The yellow-bellied marmot is primarily polygynous with an intermediate level of sociality and low reproductive skew among females. In contrast, all other social marmot species are mainly monogamous, highly social and with marked reproductive skew among females. To understand the evolution of this difference in reproductive skew, I examined four possible explanations identified From reproductive skew theory. From the literature, I then reviewed evidence to investigate if marmot species differ in: (1) the ability of dominants to control the reproduction of subordinates; (2) the degree of relatedness between group members; (3) the benefit for subordinates of remaining in the social group; and (4) the benefit for dominants of retaining subordinates. I found that the optimal skew hypothesis may apply for both sets of species. I suggest that yellow-bellied marmot females may benefit from retaining subordinate females and in return have to concede them reproduction. On the contrary, monogamous marmot species may gain by suppressing the reproduction of subordinate females to maximise the efficiency of social thermoregulation, even at the risk of departure of subordinate females from the family group. Finally, I discuss scenarios for the simultaneous evolution of sociality, monogamy and reproductive skew in marmots. (C) 2000 Elsevier Science B.V. All rights reserved

Copulatory behaviour of alpine marmots (Marmota marmota)

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Postweaning mass gain in juvenile alpine marmots Marmota marmota

International audienceThe effects of several environmental factors on the postweaning growth of wild Alpine marmots were investigated. Factors considered were year of birth, sun exposure in the home range, litter size, and sex of young, Components of growth were juvenile mass at emergence from the natal burrow (as a result of preweaning growth) and postweaning growth rate. We also considered the length of the active season during which growth occurs. Mass at emergence and postweaning growth rate varied according to year of birth, were higher in south-facing than in north-facing home ranges, and were higher in small litters. Mass at emergence was higher for males than for females. We suggest that environmental factors affected the juvenile growth pattern through influences on maternal body condition. Our results support Trombulak's hypothesis that mothers maintain as many young as physiologically possible. We suggest that mothers in poor condition sacrificed the mass of their offspring rather than their number. A body mass sexual dimorphism of juveniles occurred at emergence, suggesting that mothers may provide more care for their male than their female offspring

Variation in survival rates for the alpine marmot (Marmota marmota): effects of sex, age, year, and climatic factors

International audienceWe examined variation in annual survival rates in a population of alpine marmots (Marmota marmota) according to intrinsic (sex and age) and extrinsic (year and climate) factors. We tested predictions concerning (i) a sex effect in a monogamous non-dimorphic species, (ii) age structure of survival rates in a mesomammal, and (iii) the annual variability effect and the contribution of stochastic climatic factors, especially snow cover, frost, and rainfall. We used a 8-year dataset of 367 marmots that were livetrapped and marked in La Sassiere Nature Reserve in the French Alps between 1990 and 1997. Survival and recapture rates were modelled using recent developments in capture-recapture models. Sex had no effect on survival rates, which agrees with the predictions of sexual selection. Survival rates for young of the year (YOY, from weaning to first birthday) were, on average, lower than in the older age class. In the older age class, annual variation occurred that was strongly related to the intensity of autumn frost. By determining the soil temperature at the beginning of hibernation, this factor, though short-lived, could have determined the energetic cost of hibernation. Neither annual variation nor an environmental effect was detected in YOY despite a large sample size. Social thermoregulation could contribute to the stability of YOY survival rates. As infanticide was common after the immigration of a new dominant male, survival of YOY seemed to depend more on social events than on stochastic climatic ones

Efficient spatial multi-state capture-recapture model to study natal dispersal. An application to the Alpine marmot.

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