Search

We tested for cross-species amplification of microsatellite loci located throughout the domestic sheep (Ovis aries) genome in two north American mountain ungulates (bighorn sheep, Ovis canadensis, and mountain goats, Oreamnos americanus). We identified 247 new polymorphic markers in bighorn sheep (≥ 3 alleles in one of two study populations) and 149 in mountain goats (≥ 2 alleles in a single study population) using 648 and 576 primer pairs, respectively. Our efforts increased the number of available polymorphic microsatellite markers to 327 for bighorn sheep and 180 for mountain goats. The average distance between successive polymorphic bighorn sheep and mountain goat markers inferred from the Australian domestic sheep genome linkage map (mean ± 1 SD) was 11.9 ± 9.2 and 15.8 ± 13.8 centimorgans, respectively. The development of genomic resources in these wildlife species enables future studies of the genetic architecture of trait variation.

In polygynous ungulates, the rut imposes constraints on male time budgets that generate a trade-off between maintenance and reproduction, leading to a reduction in time spent foraging. As mating activities can incur substantial somatic costs, males are expected to spend their ‘nonrutting' time recovering during the breeding season. If the diminution in time allocated to foraging by males is only a consequence of time budget constraints, males should keep a similar ratio of time spent foraging to lying to that observed in the pre-rut, leading to an overall reduction of these two activities (the ‘foraging constraint' hypothesis). Alternatively, if males adopt an energy-saving strategy, they should limit energy expenditures by reducing foraging but not lying time, as the energy gains of forage intake may not meet the basal energetic requirements, especially in northern and temperate regions (the ‘energy-saving' hypothesis). Here, we contrast these two hypotheses by comparing individual daily time budgets of marked adult bighorn sheep rams (Ovis canadensis) and male mountain goats (Oreamnos americanus) during the pre-rut and the rut. Concordant results for both species support the ‘foraging constraint' hypothesis, as sexually-active males reduced time spent foraging and lying from the pre-rut to the rut because of an increase in time spent in mating-related activities. Bighorn sheep rams also increased time spent foraging when not engaged in mating tactics, providing further support for a ‘maximisation' of energy intake in the absence of reproductive opportunities. Because there are also known physiological changes that occur during the rut which may cause appetite suppression, for example to produce metabolic compounds linked with olfactory communication (the ‘scent-urination' hypothesis) or to cope with increased burden of parasites (the ‘parasite-induced anorexia' hypothesis), further research should aim at simultaneously testing these current hypotheses to better un

In mammalian polygynous mating systems, male reproductive effort consists mainly of male–male competition and courting of females, which entail substantial somatic costs. Males are thus expected to adjust their reproductive effort according to their age and condition. In this study, we examined how activity budgets of male mountain goats (Oreamnos americanus), a polygynous ungulate, varied with age in a marked population over two periods: (1) summers 1995–2006 and (2) ruts 2004–2006. We then assessed if the proportions of time spent in male–male competition and courtship behaviors were influenced by age-specific body mass and social rank during the rut. Males spent most of their time foraging and resting during summer, and rested more and foraged less with increasing age. During the rut, pronounced shifts in activity budgets occurred as juveniles (1–2 years) increased time spent foraging, whereas adults (≥3 years) increased standing and time spent in social interactions at the expense of foraging. At old age, reproductive effort either stabilized or decreased slightly, providing weak support for the ‘mating strategy–effort’ hypothesis, predicting that courtship behaviors should peak in prime-aged males. Age-specific body mass did not affect time spent in male–male competition, but was positively related with time spent in courtship behaviors, providing support for the ‘individual quality’ hypothesis, predicting that males with more resources at the start of the rut should spend more time in mating-related activities. Age-specific social rank did not affect reproductive effort. Surviving to prime age while increasing mass each year should thus allow male ungulates to gain greater ability to court estrus females.

In polygynous mammals, mating success of males often depends on intense male-male competition and the use of alternative mating tactics. Because reproduction incurs substantial energetic costs and risks of fight injuries, mate selection by males should be expected, particularly when females vary in their ability to produce offspring but can only be defended 1 at a time. Here, we investigated during 3 ruts how age and social rank of male mountain goats (Oreamnos americanus) affected the formation of consort pairs with females (“tending” tactic) in a marked population at Caw Ridge, Alberta, Canada. Among consort pairs, we quantified the behaviors of males and females, and the use of an alternative mating tactic by competing males, “coursing,” which consists of disrupting the pair to gain temporarily access to the female, often by pursuing her. Mate choice was assessed by testing if old and dominant males observed in consort pairs tended experienced females more often than younger females, because reproductive success of females increases with age. Males in consort pairs were ≥4 years old and most (86%, n = 59) were in the top one-half of the dominance hierarchy. Age and social rank of males were positively related to age of females and the total number of young produced by the tended female. All observed matings (n = 32) occurred between 14 November and 2 December and 91% were between males and females in consort pairs. Subordinate males gained mating access to females through coursing, but this tactic was rare. Our study provides evidences of mate choice by males for experienced females in an ungulate and the 1st quantitative information on the rut of mountain goats.

Major histocompatibility complex (MHC) genes are the most polymorphic in vertebrates and code for molecules playing a central role in pathogen resistance. We studied levels of MHC DRB class II diversity in a long-term study population of mountain goats (Oreamnos americanus) at Caw Ridge, Alberta, and two other populations from British Columbia, Canada. Only two alleles were found among the three populations sampled. The Caw Ridge population was fixed for one of the two MHC DRB alleles, but this lack of variation did not appear to have affected it negatively because the population doubled over two decades and had no history of any apparent infectious diseases. Past population bottlenecks during Pleistocene glaciations are thought to have been the main factor contributing to the low levels of MHC diversity in mountain goats, a hypothesis supported by our previous work reporting low polymorphism at neutral loci. Additionally, the limited MHC variability in mountain goats may be related to its northern distribution as we found that allelic diversity at MHC DRB class II in wild ungulates decreases with increasing latitude, possibly as a result of low parasite diversity at high latitudes. The low MHC variation in mountain goats and other northern ungulates such as muskoxen (Ovibos moschatus) may expose these species to population outbreaks that could be generated by introduced pathogens or northward shifts in the distribution of pathogens with global climate warming.

We report the results of a cross-species amplification test of 156 bovine, ovine and cervid microsatellite markers in a wild population of mountain goats, Oreamnos americanus, inhabiting Caw Ridge, Alberta, Canada. Twenty-nine markers were found to be low to moderately polymorphic with between two to nine alleles per locus. Observed heterozygosity ranged from 0.14 to 0.85 for a sample of 215 mountain goats. This set of markers will be used in parentage analyses to construct the pedigree of the long-term studied population and to investigate the effects of individual genetic variability on life-history traits.

Catch-curve analyses are routinely used to estimate instantaneous mortality (Z) in fish, and as the age-frequency data are often over dispersed, the application of a variance bias-correction factor has been recommended. The extensions of the Poisson generalized linear model (GLMPoisson) may, however, constitute a better alternative, as they model the variance (SE) in counts more adequately with their specific dispersion parameter for more accurate estimations and statistical comparisons. To test this idea, simulated age-frequency data generated under four dispersion scenarios were analyzed according to six currently available methods and compared with the results of a GLMPoisson and five of its extensions to evaluate each method-specific bias in Z SE estimates. Empirical age-frequency data from sampled Walleye Sander vitreus and Arctic Char Salvelinus alpinus populations in Quebec, Canada, were then used ´ to illustrate the applicability of our GLM-based method, which relies on the behavior of Pearson residuals to assess model adequacy and an information-theoretic approach for model selection. All analyses revealed that Z-estimates were generally accurate among the methods considered, except under the most likely situation of quadratic over dispersion met in ecological studies, for which only the negative binomial type 2 and the mean-parametrized Conway– Maxwell–Poisson (CMP) extensions were adequate to estimate both Z and its SE. Linearly over dispersed data were best modeled by the negative binomial type 1 and generalized Poisson (GLMGP) extensions; the GLMCMP and GLMGP were the most appropriate to model under dispersed data, whereas the GLM Poisson adequately modeled equi- dispersed data, similar to the Chapman and Robson (1960) method. Statistical comparisons of Z SE for grouping factors, such as year or site, were correctly achieved when the most adequate and statistically supported GLM Poisson extension was applied. Altogether, the proposed GLM-based method sh

The association between population dynamics and genetic variability is of fundamental importance for both evolutionary and conservation biology. We combined long-term population monitoring and molecular genetic data from 123 offspring and their parents at 28 microsatellite loci to investigate changes in genetic diversity over 14 cohorts in a small and relatively isolated population of mountain goats (Oreamnos americanus) during a period of demographic increase. Offspring heterozygosity decreased while parental genetic similarity and inbreeding coefficients (FIS) increased over the study period (1995–2008). Immigrants introduced three novel alleles into the population and matings between residents and immigrants produced more heterozygous offspring than local crosses, suggesting that immigration can increase population genetic variability. The population experienced genetic drift over the study period, reflected by a reduced allelic richness over time and an ‘isolation-by-time’ pattern of genetic structure. The temporal decline of individual genetic diversity despite increasing population size probably resulted from a combination of genetic drift due to small effective population size, inbreeding and insufficient counterbalancing by immigration. This study highlights the importance of long-term genetic monitoring to understand how demographic processes influence temporal changes of genetic diversity in long-lived organisms.

We tested for cross-species amplification of microsatellite loci located throughout the domestic sheep (Ovis aries) genome in two north American mountain ungulates (bighorn sheep, Ovis canadensis, and mountain goats, Oreamnos americanus). We identified 247 new polymorphic markers in bighorn sheep (≥ 3 alleles in one of two study populations) and 149 in mountain goats (≥ 2 alleles in a single study population) using 648 and 576 primer pairs, respectively. Our efforts increased the number of available polymorphic microsatellite markers to 327 for bighorn sheep and 180 for mountain goats. The average distance between successive polymorphic bighorn sheep and mountain goat markers inferred from the Australian domestic sheep genome linkage map (mean ± 1 SD) was 11.9 ± 9.2 and 15.8 ± 13.8 centimorgans, respectively. The development of genomic resources in these wildlife species enables future studies of the genetic architecture of trait variation.

In polygynous ungulates, the rut imposes constraints on male time budgets that generate a trade-off between maintenance and reproduction, leading to a reduction in time spent foraging. As mating activities can incur substantial somatic costs, males are expected to spend their ‘nonrutting' time recovering during the breeding season. If the diminution in time allocated to foraging by males is only a consequence of time budget constraints, males should keep a similar ratio of time spent foraging to lying to that observed in the pre-rut, leading to an overall reduction of these two activities (the ‘foraging constraint' hypothesis). Alternatively, if males adopt an energy-saving strategy, they should limit energy expenditures by reducing foraging but not lying time, as the energy gains of forage intake may not meet the basal energetic requirements, especially in northern and temperate regions (the ‘energy-saving' hypothesis). Here, we contrast these two hypotheses by comparing individual daily time budgets of marked adult bighorn sheep rams (Ovis canadensis) and male mountain goats (Oreamnos americanus) during the pre-rut and the rut. Concordant results for both species support the ‘foraging constraint' hypothesis, as sexually-active males reduced time spent foraging and lying from the pre-rut to the rut because of an increase in time spent in mating-related activities. Bighorn sheep rams also increased time spent foraging when not engaged in mating tactics, providing further support for a ‘maximisation' of energy intake in the absence of reproductive opportunities. Because there are also known physiological changes that occur during the rut which may cause appetite suppression, for example to produce metabolic compounds linked with olfactory communication (the ‘scent-urination' hypothesis) or to cope with increased burden of parasites (the ‘parasite-induced anorexia' hypothesis), further research should aim at simultaneously testing these current hypotheses to better un

In mammalian polygynous mating systems, male reproductive effort consists mainly of male–male competition and courting of females, which entail substantial somatic costs. Males are thus expected to adjust their reproductive effort according to their age and condition. In this study, we examined how activity budgets of male mountain goats (Oreamnos americanus), a polygynous ungulate, varied with age in a marked population over two periods: (1) summers 1995–2006 and (2) ruts 2004–2006. We then assessed if the proportions of time spent in male–male competition and courtship behaviors were influenced by age-specific body mass and social rank during the rut. Males spent most of their time foraging and resting during summer, and rested more and foraged less with increasing age. During the rut, pronounced shifts in activity budgets occurred as juveniles (1–2 years) increased time spent foraging, whereas adults (≥3 years) increased standing and time spent in social interactions at the expense of foraging. At old age, reproductive effort either stabilized or decreased slightly, providing weak support for the ‘mating strategy–effort’ hypothesis, predicting that courtship behaviors should peak in prime-aged males. Age-specific body mass did not affect time spent in male–male competition, but was positively related with time spent in courtship behaviors, providing support for the ‘individual quality’ hypothesis, predicting that males with more resources at the start of the rut should spend more time in mating-related activities. Age-specific social rank did not affect reproductive effort. Surviving to prime age while increasing mass each year should thus allow male ungulates to gain greater ability to court estrus females.

Major histocompatibility complex (MHC) genes are the most polymorphic in vertebrates and code for molecules playing a central role in pathogen resistance. We studied levels of MHC DRB class II diversity in a long-term study population of mountain goats (Oreamnos americanus) at Caw Ridge, Alberta, and two other populations from British Columbia, Canada. Only two alleles were found among the three populations sampled. The Caw Ridge population was fixed for one of the two MHC DRB alleles, but this lack of variation did not appear to have affected it negatively because the population doubled over two decades and had no history of any apparent infectious diseases. Past population bottlenecks during Pleistocene glaciations are thought to have been the main factor contributing to the low levels of MHC diversity in mountain goats, a hypothesis supported by our previous work reporting low polymorphism at neutral loci. Additionally, the limited MHC variability in mountain goats may be related to its northern distribution as we found that allelic diversity at MHC DRB class II in wild ungulates decreases with increasing latitude, possibly as a result of low parasite diversity at high latitudes. The low MHC variation in mountain goats and other northern ungulates such as muskoxen (Ovibos moschatus) may expose these species to population outbreaks that could be generated by introduced pathogens or northward shifts in the distribution of pathogens with global climate warming.

We report the results of a cross-species amplification test of 156 bovine, ovine and cervid microsatellite markers in a wild population of mountain goats, Oreamnos americanus, inhabiting Caw Ridge, Alberta, Canada. Twenty-nine markers were found to be low to moderately polymorphic with between two to nine alleles per locus. Observed heterozygosity ranged from 0.14 to 0.85 for a sample of 215 mountain goats. This set of markers will be used in parentage analyses to construct the pedigree of the long-term studied population and to investigate the effects of individual genetic variability on life-history traits.