TY - JOUR A1 - Eccard, Jana A1 - Herde, Antje T1 - Seasonal variation in the behaviour of a short-lived rodent JF - BMC ecology N2 - Background: Short lived, iteroparous animals in seasonal environments experience variable social and environmental conditions over their lifetime. Animals can be divided into those with a "young-of-the-year" life history (YY, reproducing and dying in the summer of birth) and an "overwinter" life history (OW, overwintering in a subadult state before reproducing next spring). We investigated how behavioural patterns across the population were affected by season and sex, and whether variation in behaviour reflects the variation in life history patterns of each season. Applications of pace-of-life (POL) theory would suggest that long-lived OW animals are shyer in order to increase survival, and YY are bolder in order to increase reproduction. Therefore, we expected that in winter and spring samples, when only OW can be sampled, the animals should be shyer than in summer and autumn, when both OW and YY animals can be sampled. We studied common vole (Microtus arvalis) populations, which express typical, intra-annual density fluctuation. We captured a total of 492 voles at different months over 3 years and examined boldness and activity level with two standardised behavioural experiments. Results: Behavioural variables of the two tests were correlated with each other. Boldness, measured as short latencies in both tests, was extremely high in spring compared to other seasons. Activity level was highest in spring and summer, and higher in males than in females. Conclusion: Being bold in laboratory tests may translate into higher risk-taking in nature by being more mobile while seeking out partners or valuable territories. Possible explanations include asset-protection, with OW animals being rather old with low residual reproductive value in spring. Therefore, OW may take higher risks during this season. Offspring born in spring encounter a lower population density and may have higher reproductive value than offspring of later cohorts. A constant connection between life history and animal personality, as suggested by the POL theory, however, was not found. Nevertheless, correlations of traits suggest the existence of animal personalities. In conclusion, complex patterns of population dynamics, seasonal variation in life histories, and variability of behaviour due to asset-protection may cause complex seasonal behavioural dynamics in a population. KW - Animal personalities KW - Boldness KW - Life history KW - Pace-of-life KW - POL KW - Phenotypic plasticity KW - Common vole Y1 - 2013 U6 - https://doi.org/10.1186/1472-6785-13-43 SN - 1472-6785 VL - 13 IS - 22 PB - BioMed Central CY - London ER - TY - JOUR A1 - Herde, Antje A1 - Eccard, Jana T1 - Consistency in boldness, activity and exploration at different stages of life JF - BMC ecology N2 - Background: Animals show consistent individual behavioural patterns over time and over situations. This phenomenon has been referred to as animal personality or behavioural syndromes. Little is known about consistency of animal personalities over entire life times. We investigated the repeatability of behaviour in common voles (Microtus arvalis) at different life stages, with different time intervals, and in different situations. Animals were tested using four behavioural tests in three experimental groups: 1. before and after maturation over three months, 2. twice as adults during one week, and 3. twice as adult animals over three months, which resembles a substantial part of their entire adult life span of several months. Results: Different behaviours were correlated within and between tests and a cluster analysis showed three possible behavioural syndrome-axes, which we name boldness, exploration and activity. Activity and exploration behaviour in all tests was highly repeatable in adult animals tested over one week. In animals tested over maturation, exploration behaviour was consistent whereas activity was not. Voles that were tested as adults with a three-month interval showed the opposite pattern with stable activity but unstable exploration behaviour. Conclusions: The consistency in behaviour over time suggests that common voles do express stable personality over short time. Over longer periods however, behaviour is more flexible and depending on life stage (i.e. tested before/after maturation or as adults) of the tested individual. Level of boldness or activity does not differ between tested groups and maintenance of variation in behavioural traits can therefore not be explained by expected future assets as reported in other studies. KW - Animal personality KW - Behavioural type KW - Microtus arvalis KW - Common vole KW - Plasticity KW - Consistency KW - Repeatability Y1 - 2013 U6 - https://doi.org/10.1186/1472-6785-13-49 SN - 1472-6785 VL - 13 IS - 12 PB - BioMed Central CY - London ER - TY - JOUR A1 - Schuster, Andrea C. A1 - Herde, Antje A1 - Mazzoni, Camila J. A1 - Eccard, Jana A1 - Sommer, Simone T1 - Evidence for selection maintaining MHC diversity in a rodent species despite strong density fluctuations JF - Immunogenetics N2 - Strong spatiotemporal variation in population size often leads to reduced genetic diversity limiting the adaptive potential of individual populations. Key genes of adaptive variation are encoded by the immune genes of the major histocompatibility complex (MHC) playing an essential role in parasite resistance. How MHC variation persists in rodent populations that regularly experience population bottlenecks remains an important topic in evolutionary genetics. We analysed the consequences of strong population fluctuations on MHC class II DRB exon 2 diversity in two distant common vole (Microtus arvalis) populations in three consecutive years using a high-throughput sequencing approach. In 143 individuals, we detected 25 nucleotide alleles translating into 14 unique amino acid MHC alleles belonging to at least three loci. Thus, the overall allelic diversity and amino acid distance among the remaining MHC alleles, used as a surrogate for the range of pathogenic antigens that can be presented to T-cells, are still remarkably high. Both study populations did not show significant population differentiation between years, but significant differences were found between sites. We concluded that selection processes seem to be strong enough to maintain moderate levels of MHC diversity in our study populations outcompeting genetic drift, as the same MHC alleles were conserved between years. Differences in allele frequencies between populations might be the outcome of different local parasite pressures and/or genetic drift. Further understanding of how pathogens vary across space and time will be crucial to further elucidate the mechanisms maintaining MHC diversity in cyclic populations. KW - MHC diversity KW - Selection KW - High-throughput next-generation sequencing KW - Population cycle KW - Common vole KW - Microtus arvalis Y1 - 2016 U6 - https://doi.org/10.1007/s00251-016-0916-z SN - 0093-7711 SN - 1432-1211 VL - 68 SP - 429 EP - 437 PB - Springer CY - New York ER -