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  • 1.
    Brochet, Anne-Laure
    et al.
    CNERA Avifaune migratrice, Office National de la Chasse et de la Faune Sauvage, Arles.
    Dessborn, Lisa
    Kristianstad University, School of Education and Environment.
    Legagneux, P.
    Département de Biologie, Université Laval, Pavillon Vachon.
    Elmberg, Johan
    Kristianstad University, School of Education and Environment.
    Gauthier-Clerc, M.
    Centre de Recherche de la Tour du Valat, Arles.
    Fritz, H.
    Université Claude Bernard Lyon 1, CNRS UMR 5558 Biométrie et Biologie Evolutive, Université de Lyon, Villeurbanne.
    Guillemain, M.
    CNERA Avifaune migratrice, Office National de la Chasse et de la Faune Sauvage, Arles.
    Is diet segregation between dabbling ducks due to food partitioning?: a review of seasonal patterns in the Western Palearctic2012In: Journal of Zoology, ISSN 0952-8369, E-ISSN 1469-7998, Vol. 286, no 3, p. 171-178Article in journal (Refereed)
    Abstract [en]

    Within the paradigm of resource-limited competition-structured communities, dabbling ducks (Anas spp.) have been used as a textbook example of how morphological differences, notably bill lamellar density and body length, may allow sympatric species to partition food and hence coexist. We reviewed all accessible diet studies from the Western Palearctic for three closely related dabbling duck species, mallard (Anas platyrhynchos), pintail (A.?acuta) and teal (A.?crecca), and present a comprehensive list of the food items (invertebrates, seeds, vegetative parts of plants) ingested. To assess the circumannual perspective of niche separation, we evaluated size distribution of ingested seeds among seasons and duck species. There was a significant difference among duck species in mean size and mass of ingested seeds, as well as in diet composition, with the largest seeds consumed by the largest species (mallard) with the coarsest bill filter apparatus (lamellae), and the smallest seeds by the smallest species (teal) with the finest bill lamellae. However, no effect of season was found, suggesting consistent diet segregation among species throughout the annual cycle of ducks and over large geographical areas. We argue that the patterns of food size separation between the three species are compatible with the idea of coexistence under interspecific competition.

  • 2.
    Faurby, Sören
    et al.
    Danmark.
    Jönsson, K. Ingemar
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man & Biosphere Health (MABH).
    Rebecchi, L.
    Italien.
    Funch, P.
    Danmark.
    Variation in anhydrobiotic survival of two eutardigrade morphospecies: a story of cryptic species and their dispersal2008In: Journal of Zoology, ISSN 0952-8369, E-ISSN 1469-7998, Vol. 275, no 2, p. 139-145Article in journal (Refereed)
    Abstract [en]

    Studies of geographic variation in anhydrobiotic tolerance may increase our understanding of the population dynamics of terrestrial meiofauna and the relative importance of local adaptation and microhabitat niche separation. Although anhydrobiosis in tardigrades has been studied extensively, few studies have dealt with intraspecific variation in survival and none of these included genetic data to validate the intraspecific nature of the comparisons. Such data are necessary when working with meiofauna as cryptic species are common. We analysed the anhydrobiotic survival and genetic variation in cytochrome oxidase subunit I of two eutardigrades (Richtersius coronifer and Ramazzottius oberhaeuseri) from Italy and Sweden to detect possible local adaptation. Survival was analysed as a multidimensional contingency table and showed that anhydrobiotic survival was higher in Sweden for Ra. oberhaeuseri whereas no significant geographic variation was found for Ri. coronifer. Our genetic analysis indicated the coexistence of two cryptic species of Ra. oberhaeuseri in Italy, only one of which was found in Sweden. It could not be determined whether the variation in Ramazzottius is intra- or interspecific due to the presence of these cryptic species. We suggest that geographic variation in anhydrobiotic survival may be a general phenomenon in tardigrades but further research is necessary to determine the degree of intraspecific variation. The genetic analysis showed indications of long-term isolation of the individual populations of Ri. coronifer but recent dispersal in one of the cryptic species of Ramazzottius. We found higher survival in Ra. oberhaeuseri than in Ri. coronifer. These results indicate a possible coupling between anhydrobiotic survival and dispersal rate.

  • 3.
    Miaud, Claude
    et al.
    University of Savoie, Mountain Interdisciplinary Scientific Center, Laboratory Aquatic Ecosystems and Interfaces, Le Bourget du Lac.
    Guyétant, Robert
    University of Savoie, Mountain Interdisciplinary Scientific Center, Laboratory Aquatic Ecosystems and Interfaces, Le Bourget du Lac.
    Elmberg, Johan
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Variations in life-history traits in the common frog Rana temporaria (Amphibia: Anura): a literature review and new data from the French Alps1999In: Journal of Zoology, ISSN 0952-8369, E-ISSN 1469-7998, Vol. 249, no 1, p. 61-73Article in journal (Refereed)
    Abstract [en]

    Life-history traits of Rana temporaria were studied in an alpine French population and in the literature. In the living frogs, mean adult body length was greater in females than in males. Sexual dimorphism in body length was 0.109 using Lovich & Gibbons (1992) formula, but tended to decrease with age. Age of adult frogs was assessed by skeletochronology, and age distribution was not significantly different between the sexes (range 4-15 years in males, 5-12 in females). Adult survival rate was about 0.80 in both sexes. Once maturity was reached, the total expected longevity was 6.1 years in males and 5.5 years in females. Age and body length were positively correlated in both sexes. The growth coefficient (K) was 0.47 in males, and 0.55 in females, mainly reflected as faster female growth between metamorphosis and maturation. Growth rate generally decreased before sexual maturity was reached. On average, females matured 1 year later than males. Newly metamorphosed froglets averaged 16.1 mm. When combined with published data from 12 European populations of R. temporaria, the following general patterns emerge. Mean adult body length is significantly greater in females than in males, and mean body length at maturity shows the same trend. Variation in mean age at maturity and in longevity are considerable among populations, but there is no consistent trend of difference between the sexes. Body length and age are correlated between males and females, i.e. populations with long and old males also have long and old females. Mean adult body length, mean body length at maturity, age at maturity, and longevity all increase with decreasing activity period. Adults exposed to a short activity period grow slower but attain a greater final length. Sexual dimorphism in body length generally increases as activity period gets shorter. Polygons describing norms of reaction for maturation in an age-body length space are similarly oriented in both sexes, but with a wider range in age for females. This is due to an older age at maturity for females in populations with a short activity season. Mean age and length at maturity are significantly correlated in females, but not in males, partly supporting the hypothesis that this species has a flexible pattern of development. Observed patterns are compared with predictions from life-history theory, paying attention to all life stages and environmental variation.

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