1. Patterns of torpor, arousal and activity in free-living Greater Horseshoe Bats, Rhinolophus ferrumequinum (Schreber), were investigated during the hibernation period by using temperature-sensitive ...radio-transmitters. 2. Torpor bouts varied between 0.1 and 11.8 days, with individual means ranging from 1.3 to 7.4 days. Torpor bout duration decreased with increasing ambient temperature. 3. Activity duration varied from 37 min to 54 h 24 min, with individual means ranging from 2:29 to 8:58 h. Activity duration increased with ambient temperatures above approximately 10 ⚬C. 4. Ten of 11 bats synchronized their arousals with dusk. The circadian rhythm of one bat showed a free-running pattern over a period of about 5 weeks. Arousals were more highly synchronized, and closer to dusk, in individuals with lower body condition. 5. That bats forage in mild weather is supported by the strong synchronization of arousals with dusk, especially in bats with low body condition. 6. Patterns of torpor and subsequent activity are consistent with predictions that torpor lasts until a critical metabolic or water imbalance is achieved. Because metabolism and water loss are temperature-dependent, torpor bout duration decreases with increasing temperature. The imbalance is corrected during subsequent activity, which is relatively constant in duration until a temperature threshold of 10 ⚬C, above which increasing levels of foraging lead to longer activity bouts.
Mating strategies that lead to increased kinship within socially cooperative groups may offer inclusive fitness benefits to individuals, but can also result in higher levels of inbreeding. Here we ...show in a sexually segregated bat species that females avoid this conflict through two mating behaviours. First, most females revisit and breed with specific, individual males across years, so that their single offspring born in different years are full siblings. Second, relatives in the maternal line, including mothers and daughters, share breeding partners (intra-lineage polygyny) more often than expected by chance. Although these behaviours increased levels of co-ancestry among colony members, there was no concomitant rise in inbreeding. We suggest that when females engage in mate fidelity and intra-lineage polygyny, kin ties among female roost mates will be strengthened, thereby potentially contributing to social group cohesiveness. Our findings reveal the hidden complexity that can underlie polygynous breeding, and highlight a new potential route by which female mate choice could influence social evolution.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Female greater horseshoe bats (Rhinolophus ferrumequinum) exhibit strong natal philopatry to their maternity roost over many years, leading to the aggregation of matrilineal kin. Maternity colonies ...may, therefore, be expected to comprise highly related individuals, and, as such, provide conditions suitable for the evolution of kin-selected behaviours. To test these predictions, we examined relatedness and behaviour among matrilineal kin within a colony in south-west Britain. Genetic analysis of 15 matrilines, identified from microsatellite genotyping and long-term ringing surveys, revealed average relatedness levels of 0.17 to 0.64. In contrast, background relatedness among colony females approximated to zero (0.03). These results suggest that inclusive fitness benefits may only be accrued through discriminate cooperation within matrilines, and not at the wider colony level. To examine whether the potential for such benefits is realised through kin- biased cooperation during foraging, females from two matrilines were radio-tracked simultaneously over 3 years. Pairwise home-range overlap correlated significantly with Hamilton's relatedness coefficient. The greatest spatial associations were observed between females and their adult daughters, which shared both foraging grounds and night roosts, sometimes over several years. Tagged females, however, generally foraged and roosted alone, suggesting that kin-biased spatial association probably does not result from either information-transfer or cooperative territorial defence. Such patterns may instead result from a mechanism of maternal inheritance of preferred foraging and roosting sites.
Following a dramatic decline last century, the British population of the endangered greater horseshoe bat Rhinolophus ferrumequinum is highly fragmented. To examine the consequences of fragmentation ...and limited dispersal on patterns of genetic structure and variation, we used microsatellite markers to screen bats from around 50% of the known maternity colonies in Britain, and two areas from continental Europe. Analyses revealed that Welsh and English colonies were genetically isolated. This, and lower variability in Britain than north France, may result from either genetic drift, or the species’ colonization history. Gene flow among most neighbouring colonies was not generally restricted, with one exception. These findings have important implications for the ongoing conservation management of this species.
We investigated intraspecific differences in evening emergence time of northern bats Eptesicus nilssonii, greater horseshoe bats Rhinolophus ferrumequinum and lesser horseshoe bats R. hipposideros. ...Significant differences in emergence time were associated with presumed variation in predation risk, related to light intensity, and energetic benefits of early emergence, caused by differences in age, reproductive state (energetic demands), and body condition. Females of both species emerged progressively later as pregnancy advanced, perhaps because of decreased flight performance, and earlier as lactation proceeded, probably because of increased energy demands and low reserves. Bats under energetic stress, due to persistent low ambient temperatures during pregnancy, or when body reserves were low, emerged relatively early, and hence appeared to take higher risks, than other bats. Young bats emerged much later than the adults at first, but progressively earlier as their flight skills improved. Lesser horseshoe bats emerged later at exposed roost exits than in more protected situations. The results largely corroborate the hypothesis that emergence time, and therefore feeding performance, of insectivorous bats is constrained at bright light conditions, possibly by predation risk (from birds), and modified by energetic considerations.
The factors influencing the survival of greater horseshoe bat (Rhinolophus ferrumequinum) offspring born over seven years at a maternity colony in south-west Britain were studied. The effects of a ...range of phenotypic and maternal variables were analysed using a historical data set. In addition, the influence of two genetic measures on mortality, individual heterozygosity and a new measure of outbreeding, termed mean d2, was assessed. Logistic regressions were undertaken with survival modelled as a binary response variable. Survival to two life stages was studied for each variable and all models were developed for both sexes separately and together. Only one variable, mean d2, was significantly associated with survival. Male offspring with high mean d2 scores were more likely to survive to their first and second summers. The influence of mean d2 was not due to a single locus under selection but a wider multilocus effect and probably represents heterosis as opposed to solely inbreeding depression. Therefore, the extent to which an individual is outbred may determine survival more than widely used phenotypic characteristics such as size and mass. Mean d2 may reflect immunocompetence, which influences mortality. Protection of mating sites in order to facilitate gene flow and, therefore, outbreeding may help to promote population stability and growth.
We have measured the proton recoil polarization in the He-4((e) over right arrow ,e(')(p) over right arrow)H-4 reaction at Q(2)=0.5, 1.0, 1.6, and 2.6 (GeV/c)(2). The measured ratio of polarization ...transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model. In addition, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control.
Tensor polarization observables ( t(20), t(21), and t(22)) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7 (GeV/c)(2). The ...experiment was performed at the Jefferson Laboratory in Hall C using the electron High Momentum Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new data determine to much larger Q2 the deuteron charge form factors G(C) and G(Q). They are in good agreement with relativistic calculations and disagree with perturbative QCD predictions.
Female greater horseshoe bats form maternity colonies each summer in order to give birth and raise young. During the mating period, females visit males occupying territorial sites, copulation takes ...place and sperm are stored until ovulation occurs, normally in April. Using microsatellite markers and a likelihood method of parentage analysis, we studied breeding behaviour and male reproductive success over a five-year period in a population of bats in south-west Britain. Paternity was assigned with 80% confidence to 44% of young born in five successive cohorts. While a small annual skew in male reproductive success was detected, the variance increased over five years due to the repeated success of a few individuals. Mating was polygynous, although some females gave birth to offspring sired by the same male in separate years. Such repeated partnerships probably result from fidelity for either mating sites or individuals or from sperm competition. Females mated with males born both within and outside their own natal colony; however, relatedness between parents was no less than the average recorded for male-female pairs. Gene flow between colonies is likely to be primarily mediated by both female and male dispersal during the mating period rather than more permanent movements.
Life history theory predicts that an individual may gain in fitness by postponing reproduction if, by doing so, future reproductive capacity or longevity is enhanced. To test this theory I studied ...the survival and fecundity of earlier (start age 2 years) and later (start age 3 years or later) breeding female bats. Mature females produce one young annually, may miss breeding in some years and can still breed at age 29 years. Earlier breeders (e b) have similar mean skeletal size and birth date to later breeders (l b), but they have higher fat reserves late in their first winter and in their second autumn, when follicular development starts, and are probably superior foragers. eb averaged 5.6 and lb 8.1 years at death. Higher mortality in the former group was associated with parturition later in July during early breeding attempts. Lifetime reproductive success (lrs) of both groups was highly variable and strongly correlated with lifespan, which explained 99 and 96% of observed variation respectively. Differences in mean lifespan had no significant effect upon the mean lrs of eb and lb (4.4 and 5.1 births per female respectively). Although earlier breeding reduces lifespan, because it starts a year earlier and breeding rates are higher in eb than in lb (96% cf. 85% per year), overall there appear to be equal fitness benefits. During rapid population recovery after a climate-induced crash, earlier breeding was enhanced and may be advantageous until the population stabilizes. Hence studies testing life history theory should take account of population trends and climate. These seem to be crucially interconnected via food availability, the growth of individuals, and fat storage.
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