Determinants and long‐term costs of early reproduction in males of a long‐lived polygynous mammal

Ritchot, Yanny; Festa‐Bianchet, Marco; Coltman, David W.; Pelletier, Fanie

doi:10.1002/ece3.7530

Cited by 11 publications

(12 citation statements)

References 70 publications

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“…Accordingly, they reach their adult weight, puberty and sexual maturity at an earlier age (Ali et al (2020); Bangar et al (2021); Iqbal et al (2021); Sharif et al, 2021). As observed in various breeds of feral sheep, this growth pattern probably allows ewe lambs to breed with heavier dominant adult males rather than young subordinate males (Ritchot et al, 2021).…”

Section: A Bmentioning

confidence: 72%

Characterization of Growth of Socorro Island Merino Lambs

Castillo

Macedo

Arredondo

et al. 2022

Chil. j. agric. anim. sci.

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The aims of this study were to evaluate the effect of genetic and non-genetic factors on the growth of Socorro Island Merino lambs and to model their growth curve using nonlinear mathematical models. The weight of 41 Socorro Island Merino lambs was recorded at birth and at 45, 90, 135, 180, 225, 270, 315 and 365 days of life from May 2019 to September 2021. The effects on growth of sex, genotype, year of birth, and parity of the dam were analyzed. Four non-linear models (Brody, Logistic, Gompertz and von Bertalanffy) were fitted for determining the best model to describe growth curve. Birth weight and pre-weaning growth rate were not affected (P 0.05) by any of the factors studied, while weaning weight was only significantly affected (P 0.05) by sex. Year of birth significantly affected (P 0.05) post-weaning growth rate and weight of the lamb from 270 days, while sex significantly affected (P 0.05) weight at 315 days. The Gompertz and Brody models were the best fitted to describe growth curves of lambs. Purebred males showed a larger response to increasing levels of energy-protein supplementation, while they had greater mature weight and lower maturation rate compared to females and crossbred males. In conclusion, knowledge of growth and factors influencing growth pattern can help implement appropriate management strategies and make decisions aimed at the conservation of Socorro Island Merino lambs.

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Section: A Bmentioning

confidence: 72%

Characterization of Growth of Socorro Island Merino Lambs

Castillo

Macedo

Arredondo

et al. 2022

Chil. j. agric. anim. sci.

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“…Four ungulate species (roe deers, reindeers, Cape mountain zebras, and bighorn sheep) introduced in the review of Hewison and Gaillard 11 exhibited a significant negative relationship between male offspring ratio and higher maternal condition (or ranking). These ungulates are polygynous, or the males thereof are dispersive 36 – 39 . Fitness functions incorporating social structures of LRC and polygamy may explain patterns of offspring sex ratios.…”

Section: Resultsmentioning

confidence: 99%

Reformulation of Trivers–Willard hypothesis for parental investment

et al. 2022

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The Trivers-Willard hypothesis (TWH) plays a central role in understanding the optimal investment strategies to male and female offspring. Empirical studies of TWH, however, yielded conflicting results. Here, we present models to predict optimal comprehensive multi-element parental strategies composed of primary sex ratio, brood size, resource allocation among offspring, and the resultant secondary sex ratio. Our results reveal that the optimal strategy depends on sex differences in the shape of offspring fitness function rather than in fitness variance. Also, the slope of the tangent line (through the origin) to the offspring fitness function can be used to predict the preferred offspring sex. We also briefly discuss links between the model and the empirical research. This comprehensive reformulation of TWH will offer a thorough understanding of multi-element parental investment strategies beyond the classical TWH.

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“…As expected, middle‐aged and mid‐ranked males had the highest probabilities to leave the population winter range during the pre‐rut and the rut, suggesting a potential breeding migration. Though rams reach sexual maturity at around 1.5 years, they are usually prevented from breeding by dominant older males until they are 3 years or older (Ritchot et al, 2021). Therefore, young adult males likely had low propensity to migrate because they had very low breeding opportunities in any ewe group.…”

Section: Discussionmentioning

confidence: 99%

Breeding migrations by bighorn sheep males are driven by mating opportunities

Lassis

Festa-Bianchet

Pelletier

2022

Ecology and Evolution

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In some species where male mating success largely depends on intrasexual competition, males can adopt migratory or resident strategies to seek breeding opportunities. The resulting mixture of resident and migrant tactics within a population can have important ecological, genetic, and evolutionary consequences for metapopulations. Bighorn sheep Ovis canadensis males establish a linear dominance hierarchy that influences their mating tactics. Some males perform breeding migrations during the pre‐rut and rut to seek mating opportunities, but little is known about these seasonal movements. We analyzed presence/absence data for 62 marked bighorn males during six mating seasons (20–32 males/year) in the Sheep River Provincial Park, Alberta, Canada, where hunting was not allowed. On average, about half of males left their natal population to rut elsewhere. The proportion of males leaving (yearly range 15%–69%) increased as the number of resident mature males increased and the populational sex ratio decreased, with fewer females during the pre‐rut. Among those leaving the park, 24% did so in October, while the trophy sheep hunting season was open. Detailed monitoring of breeding migrations in protected populations could inform management strategies to limit evolutionary impacts of hunting, which can alter size‐dependent mortality and create artificial pressures driving changes on heritable traits.

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Determinants and long‐term costs of early reproduction in males of a long‐lived polygynous mammal

Cited by 11 publications

References 70 publications

Characterization of Growth of Socorro Island Merino Lambs

Characterization of Growth of Socorro Island Merino Lambs

Reformulation of Trivers–Willard hypothesis for parental investment

Breeding migrations by bighorn sheep males are driven by mating opportunities

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