Maternal longevity and offspring sex in wild ungulates

Douhard, Mathieu; Festa‐Bianchet, Marco; Hamel, Sandra; Nussey, Daniel H.; Côté, Steeve D.; Pemberton, Josephine M.; Pelletier, Fanie

doi:10.1098/rspb.2018.1968

Cited by 9 publications

(8 citation statements)

References 75 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, the number of lambs weaned between 2 and 7 y of age was positively correlated with the number of lambs weaned after 7 y of age. We have previously failed to detect any cost of early-life reproduction on future longevity for females in this population (9,28). On the contrary, longevity was positively correlated with both the number of lambs and the number of sons weaned between the ages of 2 and 7 y (28).…”

Section: Discussionmentioning

confidence: 97%

“…Reproduction early in life therefore occurred between 2 and 7 y inclusively. This period overlaps the latest age at first reproduction (9). We measured the number and sex ratio of lambs weaned rather than produced during early life for two reasons.…”

Section: Methodsmentioning

confidence: 99%

“…The increased energetic costs of rearing sons depress maternal reproductive performance and survival probability in the subsequent breeding season in several mammal species (reviewed in ref. 9), with important implications for evolution of adaptive sex-ratio adjustment (10,11). However, although some costs can occur only after a certain amount of physiological damage has accumulated (12), we know little about the long-term effects of offspring sex ratio on parental traits.…”

mentioning

confidence: 99%

“…This period, associated with age-independent survival, is also known as the "prime age" (26). We have recently shown that in this population the number of sons weaned during early life is not associated with reduced maternal life span (9). However, links between sex allocation and senescence remain unexplored in any species.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Sons accelerate maternal aging in a wild mammal

Douhard

Festa-Bianchet

Pelletier

2020

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

Aging, or senescence, is a progressive deterioration of physiological function with age. It leads to age-related declines in reproduction (reproductive senescence) and survival (actuarial senescence) in most organisms. However, senescence patterns can be highly variable across species, populations, and individuals, and the reasons for such variations remain poorly understood. Evolutionary theories predict that increases in reproductive effort in early life should be associated with accelerated senescence, but empirical tests have yielded mixed results. Although in sexually size-dimorphic species offspring of the larger sex (typically males) commonly require more parental resources, these sex differences are not currently incorporated into evolutionary theories of aging. Here, we show that female reproductive senescence varies with both the number and sex ratio of offspring weaned during early life, using data from a long-term study of bighorn sheep. For a given number of offspring, females that weaned more sons than daughters when aged between 2 and 7 y experienced faster senescence in offspring survival in old age. By contrast, analyses of actuarial senescence showed no cost of early-life reproduction. Our results unite two important topics in evolutionary biology: life history and sex allocation. Offspring sex ratio may help explain among-individual variation in senescence rates in other species, including humans.

show abstract

Section: Discussionmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Sons accelerate maternal aging in a wild mammal

Douhard

Festa-Bianchet

Pelletier

2020

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The interspecific difference in the cost of sons may be related to the much greater frequency of prolonged maternal care in mountain goats that frequently nurse yearlings of both sexes, compared to bighorn sheep that usually wean their lambs in late autumn (Figure and Section ). Offspring sex ratio in early life, however, did not affect longevity in either species (Douhard, Festa‐Bianchet, Hamel, et al, ).…”

Section: Sons Are Costlier But Adaptive Sex Ratio Manipulation Is Rarementioning

confidence: 94%

Long‐term studies of bighorn sheep and mountain goats reveal fitness costs of reproduction

Festa‐Bianchet

Côté

Hamel

et al. 2019

Journal of Animal Ecology

Self Cite

View full text Add to dashboard Cite

Fitness costs of reproduction are expected when resources are limited. Costs drive the evolution of life‐history strategies and can affect population dynamics if females change their allocation of resources to reproduction. We studied fitness costs of reproduction in mountain ungulates in Alberta, Canada. We monitored two populations of bighorn sheep (Ovis canadensis) for 44 and 30 years, and one of mountain goats (Oreamnos americanus) for 30 years. Both species are highly iteroparous. Heterogeneity in individual reproductive potential makes fitness costs of reproduction difficult to detect and quantify without manipulations. In capital breeders, individual differences can be partly accounted for by considering body mass and other correlates of reproductive potential. Long‐term monitoring can reveal costs that only manifest under stressful conditions such as disease or resource scarcity. Despite individual differences in reproductive potential, we detected fitness costs of reproduction in females. Costs, in terms of mass gain and survival, are almost entirely born by subsequent offspring, as mothers prioritize their own maintenance and survival. Costs are greater for primiparous females, decrease with increasing body mass and increase as resource availability declines, and sons are costlier than daughters. Costs may increase for senescent females that appear to reduce allocation to reproduction. In bighorn sheep, costs mostly involve reduced mass gain and lower survival of subsequent offspring. In mountain goats, costs include reductions in mass gain, subsequent fecundity and juvenile survival. In males, fitness costs derive mostly from attempts to reproduce rather than from siring success and likely depend upon individual competitiveness. In the absence of selective harvests, dominant males may enjoy high fitness and possibly lower costs compared to subordinates. The conservative reproductive tactic of mountain ungulate females likely explains why density dependence mostly involves later primiparity and lower recruitment, but rarely affects adult survival. Future research will seek to better account for heterogeneity in reproductive potential, assess cumulative reproductive costs and investigate the potential effects of fathers on maternal allocation tactics.

show abstract