Evidence of high individual variability in seed management by scatter-hoarding rodents: does ‘personality’ matter?

Feldman M., Ferrandiz-Rovira M., Espelta J.M., Muñoz A. (2019) Evidence of high individual variability in seed management by scatter-hoarding rodents: does ‘personality’ matter?. Animal Behaviour. 150: 167-174.
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Doi: 10.1016/j.anbehav.2019.02.009

Resum:

The predation and dispersal of seeds by scatter-hoarding animals is one of the most studied processes in the context of animal–plant interactions. Seed management by these animals has been traditionally approached at the population level: the patterns documented in the field are assumed to be similar for all individuals of the population and the variability within the population is considered to be random noise. However, little is known about to what extent this variability responds to different and consistent behaviours between individuals. The aim of this study was to analyse the individual variation and consistency in behaviour of scatter-hoarding rodents within a population. As our model we used the wood mouse, Apodemus sylvaticus, a key disperser of holm oak acorns, Quercus ilex, which, in turn, suffers high predation pressure by the common genet, Genetta genetta. In two sets of laboratory experiments, we compared the variance and consistency in behaviours and acorn management due to individual differences with that due to manipulation, using genet scents, of the perceived predation risk. Genet scents reduced the activity (i.e. time out of the refuge) in all wood mice, but the differences and consistency in activity between individuals accounted for most of the variance. Also, mice showed different and consistent stress or relaxed behaviours. Most of the variance in seed management variables, such as dispersal distance and seed size selection, was explained by consistent differences between individuals across scent treatments. The increase in stress behaviours and decrease in relaxed behaviours were positively related to dispersal ability (i.e. longer distances and larger acorns). Our study highlights the importance of considering the individual component of behaviour in scatter-hoarding rodents. This fine-scale level, largely overlooked in the ecological framework, will help to increase our understanding of seed management by scatter-hoarding animals. © 2019 The Association for the Study of Animal Behaviour

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Multiple geographic origins and high genetic differentiation of the Alpine marmots reintroduced in the Pyrenees

Bichet C., Sauzet S., Averty L., Dupont P., Ferrandiz-Rovira M., Ferrari C., Figueroa I., Tafani M., Rézouki C., López B.C., Cohas A. (2016) Multiple geographic origins and high genetic differentiation of the Alpine marmots reintroduced in the Pyrenees. Conservation Genetics. : 1-13.
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Doi: 10.1007/s10592-016-0851-4

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Reintroductions inherently involve a small number of founders leading reintroduced populations to be prone to genetic drift and, consequently, to inbreeding depression. Assessing the origins as the genetic diversity and structure of reintroduced populations compared to native populations are thus crucial to foresee their future. Here, we aim to clarify the origins of the Alpine marmots reintroduced in the Pyrenees and to evaluate the genetic consequences of this reintroduction after almost 30 years without monitoring. We search for the origins and compare the genetic structure and the genetic variability of three reintroduced Pyrenean and eight native Alpine populations using pairwise genetic distances, Bayesian clustering method and multivariate analyses. Our results reveal that the Alpine marmots reintroduced in the Pyrenees originated both from the Northern and the Southern Alps, and that, despite these multiple origins, none of the current Pyrenean marmots are admixed. The reintroduction led to a strong genetic differentiation and to a decrease in genetic diversity. This pattern likely results from the small number of founders and the low dispersal capacities of Alpine marmots and thus, highlight the necessity to consider both genetic characteristics and natural history when reintroducing a species. © 2016 Springer Science+Business Media Dordrecht

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Mate choice for neutral and MHC genetic characteristics in Alpine marmots: different targets in different contexts?

Ferrandiz-Rovira M., Allainé D., Callait-Cardinal M.-P., Cohas A. (2016) Mate choice for neutral and MHC genetic characteristics in Alpine marmots: different targets in different contexts?. Ecology and Evolution. 6: 4243-4257.
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Doi: 10.1002/ece3.2189

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Sexual selection through female mate choice for genetic characteristics has been suggested to be an important evolutionary force maintaining genetic variation in animal populations. However, the genetic targets of female mate choice are not clearly identified and whether female mate choice is based on neutral genetic characteristics or on particular functional loci remains an open question. Here, we investigated the genetic targets of female mate choice in Alpine marmots (Marmota marmota), a socially monogamous mammal where extra-pair paternity (EPP) occurs. We used 16 microsatellites to describe neutral genetic characteristics and two MHC loci belonging to MHC class I and II as functional genetic characteristics. Our results reveal that (1) neutral and MHC genetic characteristics convey different information in this species, (2) social pairs show a higher MHC class II dissimilarity than expected under random mate choice, and (3) the occurrence of EPP increases when social pairs present a high neutral genetic similarity or dissimilarity but also when they present low MHC class II dissimilarity. Thus, female mate choice is based on both neutral and MHC genetic characteristics, and the genetic characteristics targeted seem to be context dependent (i.e., the genes involved in social mate choice and genetic mate choice differ). We emphasize the need for empirical studies of mate choice in the wild using both neutral and MHC genetic characteristics because whether neutral and functional genetic characteristics convey similar information is not universal. © 2016 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

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Male-biased litter sex ratio in the southernmost Iberian population of edible dormouse: A strategy against isolation?

Ferrandiz-Rovira, M., Freixas, L., Torre, I., Míguez, S., Arrizabalaga, A. (2016) Male-biased litter sex ratio in the southernmost Iberian population of edible dormouse: A strategy against isolation?. Animal Biology. 66: 415-425.
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Doi: 10.1163/15707563-00002512

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Do pre- and post-copulatory sexually selected traits covary in large herbivores?

Ferrandiz-Rovira M., Lemaitre J.-F., Lardy S., Lopez B.C., Cohas A. (2014) Do pre- and post-copulatory sexually selected traits covary in large herbivores?. BMC Evolutionary Biology. 14: 0-0.
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Doi: 10.1186/1471-2148-14-79

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Background: In most species, males compete to gain both matings (via pre-copulatory competition) and fertilizations (via post-copulatory competition) to maximize their reproductive success. However, the quantity of resources devoted to sexual traits is finite, and so males are predicted to balance their investment between pre- and post-copulatory expenditure depending on the expected pay-offs that should vary according to mating tactics. In Artiodactyla species, males can invest in weapons such as horns or antlers to increase their mating gains or in testes mass/sperm dimensions to increase their fertilization efficiency. Moreover, it has been suggested that in these species, males with territory defence mating tactic might preferentially increase their investment in post-copulatory traits to increase their fertilization efficiency whereas males with female defence mating tactic might increase their investment in pre-copulatory sexually selected traits to prevent other males from copulating with females. In this study, we thus test the prediction that male's weapon length (pre-copulatory trait) covaries negatively with relative testes size and/or sperm dimensions (post-copulatory traits) across Artiodactyla using a phylogenetically controlled framework. Results: Surprisingly no association between weapon length and testes mass is found but a negative association between weapon length and sperm length is evidenced. In addition, neither pre- nor post-copulatory traits were found to be affected by male mating tactics. Conclusions: We propose several hypotheses that could explain why male ungulates may not balance their reproductive investment between pre- and post-copulatory traits. © 2014Ferrandiz-Rovira et al.; licensee BioMed Central Ltd.

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Worker size-related task partitioning in the foraging strategy of a seed-harvesting ant species

Arnan X., Ferrandiz-Rovira M., Pladevall C., Rodrigo A. (2011) Worker size-related task partitioning in the foraging strategy of a seed-harvesting ant species. Behavioral Ecology and Sociobiology. 65: 1881-1890.
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Doi: 10.1007/s00265-011-1197-z

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Messor bouvieri is a seed-harvesting ant species in which workers forage in trails from the nest to a search area. A previous observation of seed transfer events between workers returning to the nest suggested potential task partitioning. In this study, we describe seed transportation and analyze the role of task partitioning in the foraging strategy of this species in terms of seed intake efficiency in relation to costs and benefits based on transport speed and task reliability. We assess the harvesting efficiency of task partitioning by comparing cooperative seed transport (CST) and individual seed transport (IST) events. Our results show task partitioning in the form of a sequence of transfer events among workers going from the search area to the nest. Importantly, and despite the weak worker polymorphism of this species, this sequence involved workers of different sizes, with seeds usually being passed along from smaller to larger workers. In addition, we show that small workers are better at finding seeds (spend less time finding a seed), and large workers are better at transporting them (were faster when walking back to the nest and lost fewer seeds). However, we failed to demonstrate that workers of different sizes are specialized in performing the task in which they excel. Overall, sequential CST in M. bouvieri results in a greater seed intake because seed search time decreases and task reliability increases, compared to IST. The determinants and adaptive benefits of CST are discussed. © 2011 Springer-Verlag.

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