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Firman RC, Ellis CM, Thorn S, Mawson PR. Parental effects on offspring sex ratio in the Numbat ( Myrmecobius fasciatus): does captivity influence paternal sex allocation? J Mammal 2023; 104:1036-1046. [PMID: 38033358 PMCID: PMC10682968 DOI: 10.1093/jmammal/gyad067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 06/03/2023] [Indexed: 12/02/2023] Open
Abstract
Sex allocation theories predict that under different ecological conditions the production of sons and daughters will affect parental fitness differently. Skewed offspring sex ratios often occur under captive conditions where individuals are exposed to nutritional and social conditions that differ from nature. Here, we analyzed 29 years of offspring sex ratio data from a captive population of an endangered marsupial, the Numbat (Myrmecobius fasciatus). We partitioned variation in offspring sex ratio based on parental origin (captive- vs. wild-bred), parental weight, maternal age, and maternal reproductive history. Our analyses revealed no effect of parental weight or maternal origin on offspring sex ratio-however, there was a significant effect of paternal origin. Data visualization indicated that captive-bred males tended to produce male-biased litters. We discuss the result in relation to recent studies that have shown that male mammals have the capacity to be arbiters of sex allocation and highlight candidate mechanisms, but consider it with caution due to the small sample size from which the result was derived. We performed a population viability analysis (PVA) to explore the potential impact of a sex ratio skew on the sustainability of the captive Numbat population under hypothetical scenarios. Our PVA revealed that supplementation with wild individuals is critical to the persistence of the captive Numbat population and that a biased sex ratio will lead to extinction of the captive colony under certain conditions. Overall, our study demonstrates that covert sex ratio skews can persist undetected in captive populations, which have the potential to become impactful and compromise population sustainability under changed management processes.
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Affiliation(s)
- Renée C Firman
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
- School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
| | - Connor M Ellis
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
- School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
| | - Sian Thorn
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
| | - Peter R Mawson
- School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
- Perth Zoo, Department of Biodiversity, Conservation and Attractions, 20 Labouchere Road, South Perth, Western Australia 6151, Australia
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2
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Rice C, Larue B, Jex B, Festa Bianchet M. Regulations and hunter preference affect mountain goat harvest and horn length. WILDLIFE BIOLOGY 2022. [DOI: 10.1002/wlb3.01056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Chad Rice
- Dépt de Biologie et Centre d'Études Nordiques, Univ. de Sherbrooke Sherbrooke QC Canada
| | - Benjamin Larue
- Dépt de Biologie et Centre d'Études Nordiques, Univ. de Sherbrooke Sherbrooke QC Canada
| | - Bill Jex
- Fish&Wildlife Branch, British Columbia Ministry of Forests Smithers BC Canada
| | - Marco Festa Bianchet
- Dépt de Biologie et Centre d'Études Nordiques, Univ. de Sherbrooke Sherbrooke QC Canada
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3
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Toni P, Forsyth DM, Festa-Bianchet M. Determinants of offspring sex in kangaroos: a test of multiple hypotheses. Behav Ecol 2021. [DOI: 10.1093/beheco/araa131] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Abstract
When the fitness costs and benefits of sons and daughters differ, offspring sex ratio manipulation could be an important reproductive tactic. We explored the effects of environment and maternal caring ability on offspring sex to test four adaptive sex ratio modification hypotheses: the extrinsic modification hypothesis (EMH), carrying capacity hypothesis (CCH), Trivers-Willard hypothesis (TWH), and cost-of-reproduction hypothesis (CRH). The EMH and CCH propose that environmental conditions shape offspring sex ratios, directly or in interaction with maternal condition. The TWH and CRH predict a positive relationship between maternal condition and production of the costlier sex. The TWH predicts that mothers with superior caring ability should produce more of the sex that can provide the greatest fitness returns from additional maternal allocation, and the CRH proposes that females with limited caring ability should reduce fitness costs by producing the cheaper sex. Repeated measures on 83 known-age eastern gray kangaroos, polygynous marsupials with strong sexual dimorphism, revealed that offspring sex ratio was independent of per capita forage, supporting neither the EMH nor CCH, but was dependent on maternal mass, consistent with the TWH and CCH. Our results, however, cannot clearly identify the ultimate cause of the relationship between maternal mass and greater production of sons. One of the three assumptions of the TWH could not be verified, and mothers of sons suffered only marginal additional fitness costs. Sex ratios in higher vertebrates are likely not solely explained by factors dependent on maternal control.
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Affiliation(s)
- Pauline Toni
- Université de Sherbrooke, 2500 boulevard de l’Université, J1K2R1 Sherbrooke, Quebec, Canada
| | - David M Forsyth
- Vertebrate Pest Research Unit, New South Wales Department of Primary Industries, Orange, NSW, Australia
| | - Marco Festa-Bianchet
- Université de Sherbrooke, 2500 boulevard de l’Université, J1K2R1 Sherbrooke, Quebec, Canada
- Research School of Biology, The Australian National University, Canberra, ACT, Australia
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4
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Douhard M, Geffroy B. Males can adjust offspring sex ratio in an adaptive fashion through different mechanisms. Bioessays 2021; 43:e2000264. [PMID: 33594712 DOI: 10.1002/bies.202000264] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 01/26/2021] [Accepted: 01/26/2021] [Indexed: 01/15/2023]
Abstract
Sex allocation research has primarily focused on offspring sex-ratio adjustment by mothers. Yet, fathers also benefit from producing more of the sex with greater fitness returns. Here, we review the state-of-the art in the study of male-driven sex allocation and, counter to the current paradigm, we propose that males can adaptively influence offspring sex ratio through a wide variety of mechanisms. This includes differential production and motility of X- versus Y-bearing sperms in mammals, variation in seminal fluid composition in haplo-diploid invertebrates, and epigenetic mechanisms in some fish and lizards exhibiting environmental sex determination. Conflicts of interest between mothers and fathers over offspring sex ratios can emerge, although many more studies are needed in this area. While many studies of sex allocation have focused on adaptive explanations with little attention to mechanisms, and vice versa, the integration of these two topics is essential for understanding male-driven sex allocation.
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Affiliation(s)
- Mathieu Douhard
- Laboratoire de Biométrie & Biologie Evolutive, Université Lyon 1, Villeurbanne, France
| | - Benjamin Geffroy
- MARBEC, Univ Montpellier, Ifremer, CNRS, IRD, Palavas-Les-Flots, France
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5
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Firman RC, Tedeschi JN, Garcia-Gonzalez F. Sperm sex ratio adjustment in a mammal: perceived male competition leads to elevated proportions of female-producing sperm. Biol Lett 2020; 16:20190929. [PMID: 32486939 DOI: 10.1098/rsbl.2019.0929] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mammal sex allocation research has focused almost exclusively on maternal traits, but it is now apparent that fathers can also influence offspring sex ratios. Parents that produce female offspring under conditions of intense male-male competition can benefit with greater assurance of maximized grand-parentage. Adaptive adjustment in the sperm sex ratio, for example with an increase in the production of X-chromosome bearing sperm (CBS), is one potential paternal mechanism for achieving female-biased sex ratios. Here, we tested this mechanistic hypothesis by varying the risk of male-male competition that male house mice perceived during development, and quantifying sperm sex ratios at sexual maturity. Our analyses revealed that males exposed to a competitive 'risk' produced lower proportions of Y-CBS compared to males that matured under 'no risk' of competition. We also explored whether testosterone production was linked to sperm sex ratio variation, but found no evidence to support this. We discuss our findings in relation to the adaptive value of sperm sex ratio adjustments and the role of steroid hormones in socially induced sex allocation.
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Affiliation(s)
- Renée C Firman
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Jamie N Tedeschi
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Francisco Garcia-Gonzalez
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.,Estacion Biológica de Doñana, CSIC, Sevilla, Spain
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6
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Todd ET, Hamilton NA, Velie BD, Thomson PC. The effects of inbreeding on covering success, gestation length and foal sex ratio in Australian thoroughbred horses. BMC Genet 2020; 21:41. [PMID: 32268877 PMCID: PMC7140579 DOI: 10.1186/s12863-020-00847-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 03/24/2020] [Indexed: 11/10/2022] Open
Abstract
Background Horses produce only one foal from an eleven-month gestation period, making the maintenance of high reproductive rates essential. Genetic bottlenecks and inbreeding can increase the frequency of deleterious variants, resulting in reduced reproductive levels in a population. In this study we examined the influence of inbreeding levels on foaling rate, gestation length and secondary sex ratio in Australian Thoroughbred mares. We also investigated the genetic change in these traits throughout the history of the breed. Phenotypic data were obtained from 27,262 breeding records of Thoroughbred mares provided by three Australian stud farms. Inbreeding was estimated using the pedigree of each individual dating back to the foundation of the breed in the eighteenth century. Results While both gestation length and foaling rate were heritable, no measurable effect of inbreeding on either trait was found. However, we did find that the genetic value for both traits had decreased within recent generations. A number of environmental factors also had significant effects on foaling rate and gestation length. Secondary sex ratio had only an extremely small paternal heritable effect and was not susceptible to environmental influences. Conclusions In contrast to racing performance, inbreeding had no measurable effect on foaling rate or gestation length in Australian Thoroughbred horses. This could be because the level of inbreeding in the population examined is not high enough to show a discernible effect on reproductive traits. Populations that experience higher levels of inbreeding due to use of artificial reproductive technologies or extremely small population sizes may show a more pronounced reduction in natural foaling rate or gestation length. It is also possible that the intensive management techniques used in the Thoroughbred population masks any negative effects of inbreeding. The decrease in the genetic value of foaling rate is likely to be because horses with unfavourable genetic potential have not yet been selected out of the population. The change in genetic value of gestation length may be due to selective breeding favouring horses with shorter pregnancies. We also found that prioritising the mating of older mares, and avoiding out of season mating could lead to an increased breeding success.
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Affiliation(s)
- Evelyn T Todd
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Natasha A Hamilton
- Racing Australia Equine Genetics Research Centre, Racing Australia, Sydney, NSW, 2000, Australia
| | - Brandon D Velie
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Peter C Thomson
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
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7
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Abstract
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.
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8
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Lavoie MD, Tedeschi JN, Garcia‐Gonzalez F, Firman RC. Exposure to male-dominated environments during development influences sperm sex ratios at sexual maturity. Evol Lett 2019; 3:392-402. [PMID: 31388448 PMCID: PMC6675145 DOI: 10.1002/evl3.123] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 04/15/2019] [Accepted: 05/21/2019] [Indexed: 11/18/2022] Open
Abstract
Different stages during development are important when it comes to phenotypic adjustments in response to external stimuli. Critical stages in mammals are the prenatal phase, where embryos are exposed to a milieu of sex steroid hormones, and the early-postnatal phase, where littermates interact and experience their incipient social environment. Further, the postmaternal environment will influence the development of traits that are linked to reproductive success in adulthood. Accumulated evidence of male-driven sex allocation establishes the currently untested hypothesis that the sperm sex ratio is a plastic trait that can be mediated to align with prevailing social conditions. Here, we used natural variation in the maternal environment and experimentally manipulated the postmaternal environment to identify the importance of these developmental phases on sperm sex ratio adjustments in wild house mice (Mus musculus domesticus). We found that male density in both environments was predictive of sperm sex ratios at sexual maturity: males from more male-biased litters and males maturing under high male density produced elevated levels of Y-chromosome-bearing sperm. Our findings indicate that the sperm sex ratio is a variable phenotypic trait that responds to the external environment, and highlight the potential that these adjustments function as a mechanism of male-driven sex allocation.
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Affiliation(s)
- Misha D. Lavoie
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
| | - Jamie N. Tedeschi
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
| | - Francisco Garcia‐Gonzalez
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
- Estacion Biológica de DoñanaCSICSevillaSpain
| | - Renée C. Firman
- School of Biological Sciences (M092), Centre for Evolutionary BiologyThe University of Western AustraliaCrawleyWA6009Australia
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9
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Festa‐Bianchet M, Côté SD, Hamel S, Pelletier F. Long‐term studies of bighorn sheep and mountain goats reveal fitness costs of reproduction. J Anim Ecol 2019; 88:1118-1133. [DOI: 10.1111/1365-2656.13002] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 03/20/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Marco Festa‐Bianchet
- Département de biologie Université de Sherbrooke Sherbrooke Québec Canada
- Centre d'études nordiques Québec City Québec Canada
| | - Steeve D. Côté
- Centre d'études nordiques Québec City Québec Canada
- Département de biologie Université Laval Sainte‐Foy Québec Canada
| | - Sandra Hamel
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries, and Economics UiT The Arctic University of Norway Tromsø Norway
| | - Fanie Pelletier
- Département de biologie Université de Sherbrooke Sherbrooke Québec Canada
- Centre d'études nordiques Québec City Québec Canada
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10
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Ceacero F, Komárková M, García AJ, Gallego L. Different maternal investment strategies for male and female calves in a polygynous mammal. Curr Zool 2019; 65:269-277. [PMID: 31263485 PMCID: PMC6595534 DOI: 10.1093/cz/zoy049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Accepted: 06/25/2018] [Indexed: 11/14/2022] Open
Abstract
Maternal effects occur when the phenotype of the mother influences that of the young to the detriment of her survival, growth or fitness. The investment of the mother can be affected by maternal body condition and/or experience. Trivers-Willard Hypothesis (TWH) and Local Resource Competition Hypothesis (LRCH) are the main hypotheses used to explain bias in birth sex-ratios in mammals, as well as for sex-biased maternal investment. Both hypotheses suggest that a different amount of investment must be expected according to the sex of the young. However, recent studies suggest that these differences are not in quantity but in the strategies: mechanisms and objectives may differ for each sex. We studied how maternal characteristics (age, body mass, body condition, and dominance status) influence relevant aspects of the birth and early growth of the calf (birth date, birth body mass, body mass at weaning, and body condition at weaning) separately for each sex; and how that investment is mediated by milk production and composition (lactose, fat, and protein). One hundred eighty-eight newborns from 75 captive red deer hinds aged from 2 to 19 years were analyzed. The main differential investment observed was related to birth date: when producing a female, hinds give birth earlier in the season only if they have a good body condition; however, when gestating a male it is the older hinds those which deliver earlier. Subsequently, milk production and composition are correlated with birth body mass in female calves, but to weaning body mass in males. Thus, only hind body mass affects the weaning body mass of female calves, compared with age and hind body mass in males. These results suggest that while TWH fits the maternal investment strategy found for male calves, it is LRCH which correlates with the maternal investment patterns observed for females.
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Affiliation(s)
- Francisco Ceacero
- Department of Animal Science and Food Processing, Faculty of Tropical AgriSciences, Czech University of Life Sciences, Kamýcká 129, 165 00 Praha 6 - Suchdol, Czech Republic
| | - Martina Komárková
- Department of Ethology, Institute of Animal Science, Přátelství 815, 104 01 Praha - Uhříněves, Czech Republic
| | - Andrés J García
- Instituto de Investigación en Recursos Cinegéticos (IREC), Consejo Superior de Investigaciones Científicas—Universidad de Castilla-La Mancha—Junta de Comunidades de Castilla-La Mancha (CSIC-UCLM-JCCM), Ronda de Toledo s/n, Ciudad Real, Spain
- Sección de Recursos Cinegéticos y Ganaderos, Instituto de Desarrollo Regional (IDR), Albacete, Spain
- Departamento de Ciencia y Tecnología Agroforestal y Genética, ETSIAM, Universidad de Castilla-La Mancha (UCLM), Albacete, Spain
| | - Laureano Gallego
- Departamento de Ciencia y Tecnología Agroforestal y Genética, ETSIAM, Universidad de Castilla-La Mancha (UCLM), Albacete, Spain
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11
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Malo AF, Gilbert TC, Riordan P. Drivers of sex ratio bias in the eastern bongo: lower inbreeding increases the probability of being born male. Proc Biol Sci 2019; 286:20190345. [PMID: 31064305 PMCID: PMC6532524 DOI: 10.1098/rspb.2019.0345] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 04/14/2019] [Indexed: 01/13/2023] Open
Abstract
Parent sex ratio allocation has consequences for individual fitness, population dynamics, and conservation. Theory predicts that parents should adjust offspring sex ratio when the fitness returns of producing male or female offspring varies. Previous studies have assumed that only mothers are capable of biasing offspring sex ratios, but have neglected fathers, given the expectation of an equal proportion of X- and Y-chromosome-bearing (CBS) sperm in ejaculates due to sex chromosome segregation at meiosis. This assumption has been recently refuted and both paternal fertility and paternal genetic quality have been shown to bias sex ratios. Here, we simultaneously test the relative contribution of paternal, maternal, and individual genetic quality, as measured by inbreeding, on the probability of being born a son or a daughter, using pedigree and lifelong offspring sex ratio data for the eastern bongo ( Tragelaphus eurycerus isaaci). Our models showed first, that surprisingly, as individual inbreeding decreases the probability of being born male increases, second, that paternal genetic effects on sex ratio were stronger than maternal genetic effects (which were absent). Furthermore, paternal effects were opposite in sign to those predicted; father inbreeding increases the probability of having sons. Previous paternal effects have been interpreted as adaptive due to sex-specific inbreeding depression for reproductive traits. We argue that in the eastern bongo, the opposite sign of the paternal effect on sex ratios results from a reversed sex-specific inbreeding depression pattern (present for female but not male reproductive traits). We anticipate that this research will help stimulate research on evolutionary constraints to sex ratios. Finally, the results open a new avenue of research to predict sex ratio allocation in an applied conservation context. Future models of sex ratio allocation should also include the predicted inbreeding level of the offspring and paternal inbreeding levels.
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Affiliation(s)
- Aurelio F. Malo
- GLOCEE - Global Change Ecology and Evolution Group, Department of Life Sciences, Universidad de Alcalá, 28871, Spain
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | - Tania C. Gilbert
- Marwell Wildlife, Thompsons Lane, Winchester, Hampshire SO21 1JH, UK
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Philip Riordan
- Marwell Wildlife, Thompsons Lane, Winchester, Hampshire SO21 1JH, UK
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
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12
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Tanaka Y, Fukano Y, Nakamura M. Effect of paternal age on the birth sex ratio in captive populations of aye‐aye (
Daubentonia madagascariensis
(Gmelin)). Zoo Biol 2019; 38:389-392. [DOI: 10.1002/zoo.21487] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 02/23/2019] [Accepted: 04/01/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Yosuke Tanaka
- Ueno Zoological GardensTokyo Zoological Park SocietyTokyo Japan
| | - Yuya Fukano
- Institute for Sustainable Agro‐ecosystem Services, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyo Japan
| | - Masato Nakamura
- Ueno Zoological GardensTokyo Zoological Park SocietyTokyo Japan
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13
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Merkling T, Hatch SA, Leclaire S, Danchin E, Blanchard P. Offspring sex-ratio and environmental conditions in a seabird with sex-specific rearing costs: a long-term experimental approach. Evol Ecol 2019. [DOI: 10.1007/s10682-019-09983-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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14
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15
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Effects of population structure and density on calf sex ratio in red deer (Cervus elaphus)—implications for management. EUR J WILDLIFE RES 2018. [DOI: 10.1007/s10344-018-1190-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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16
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Malo AF, Martinez-Pastor F, Garcia-Gonzalez F, Garde J, Ballou JD, Lacy RC. A father effect explains sex-ratio bias. Proc Biol Sci 2018; 284:rspb.2017.1159. [PMID: 28855362 DOI: 10.1098/rspb.2017.1159] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/19/2017] [Indexed: 11/12/2022] Open
Abstract
Sex ratio allocation has important fitness consequences, and theory predicts that parents should adjust offspring sex ratio in cases where the fitness returns of producing male and female offspring vary. The ability of fathers to bias offspring sex ratios has traditionally been dismissed given the expectation of an equal proportion of X- and Y-chromosome-bearing sperm (CBS) in ejaculates due to segregation of sex chromosomes at meiosis. This expectation has been recently refuted. Here we used Peromyscus leucopus to demonstrate that sex ratio is explained by an exclusive effect of the father, and suggest a likely mechanism by which male-driven sex-ratio bias is attained. We identified a male sperm morphological marker that is associated with the mechanism leading to sex ratio bias; differences among males in the sperm nucleus area (a proxy for the sex chromosome that the sperm contains) explain 22% variation in litter sex ratio. We further show the role played by the sperm nucleus area as a mediator in the relationship between individual genetic variation and sex-ratio bias. Fathers with high levels of genetic variation had ejaculates with a higher proportion of sperm with small nuclei area. This, in turn, led to siring a higher proportion of sons (25% increase in sons per 0.1 decrease in the inbreeding coefficient). Our results reveal a plausible mechanism underlying unexplored male-driven sex-ratio biases. We also discuss why this pattern of paternal bias can be adaptive. This research puts to rest the idea that father contribution to sex ratio variation should be disregarded in vertebrates, and will stimulate research on evolutionary constraints to sex ratios-for example, whether fathers and mothers have divergent, coinciding, or neutral sex allocation interests. Finally, these results offer a potential explanation for those intriguing cases in which there are sex ratio biases, such as in humans.
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Affiliation(s)
- Aurelio F Malo
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK .,Chicago Zoological Society, Brookfield, IL, USA.,Smithsonian Conservation Biology Institute, Washington, DC, USA
| | - Felipe Martinez-Pastor
- SaBio IREC (CSIC-UCLM-JCCM), Campus Universitario s. n. 02071, Albacete, Spain.,INDEGSAL and Molecular Biology (Cell Biology), University of León, León, Spain
| | - Francisco Garcia-Gonzalez
- Estacion Biológica de Doñana, CSIC, Sevilla, Spain.,Centre for Evolutionary Biology, The University of Western Australia, Crawley, Western Australia, Australia
| | - Julián Garde
- SaBio IREC (CSIC-UCLM-JCCM), Campus Universitario s. n. 02071, Albacete, Spain
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17
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Douhard M, Festa-Bianchet M, Pelletier F. Maternal condition and previous reproduction interact to affect offspring sex in a wild mammal. Biol Lett 2017; 12:rsbl.2016.0510. [PMID: 27512136 DOI: 10.1098/rsbl.2016.0510] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 07/18/2016] [Indexed: 11/12/2022] Open
Abstract
Trivers and Willard proposed that offspring sex ratio should vary with maternal condition when condition, meant as maternal capacity to care, has different fitness consequences for sons and daughters. In polygynous and dimorphic species, mothers in good condition should preferentially produce sons, whereas mothers in poor condition should produce more daughters. Despite its logical appeal, support for this hypothesis has been inconsistent. Sex-ratio variation may be influenced by additional factors, such as environmental conditions and previous reproduction, which are often ignored in empirical studies. We analysed 39 years of data on bighorn sheep (Ovis canadensis) that fit all the assumptions of the Trivers-Willard hypothesis. Production of sons increased with maternal condition only for mothers that weaned a son the previous year. This relationship likely reflects a mother's ability to bear the higher reproductive costs of sons. The interaction between maternal condition and previous weaning success on the probability of producing a son was independent of the positive effect of paternal reproductive success. Maternal and paternal effects accounted for similar proportions of the variance in offspring sex. Maternal reproductive history should be considered in addition to current condition in studies of sex allocation.
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Affiliation(s)
- Mathieu Douhard
- Département de Biologie and Centre d'Études Nordiques, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, Canada J1 K 2R1
| | - Marco Festa-Bianchet
- Département de Biologie and Centre d'Études Nordiques, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, Canada J1 K 2R1
| | - Fanie Pelletier
- Département de Biologie and Centre d'Études Nordiques, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, Canada J1 K 2R1
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18
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Affiliation(s)
- Mathieu Douhard
- Département de Biologie; Université de Sherbrooke; 2500 boulevard de l’ Université Sherbrooke QC J1K 2R1 Canada
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19
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Frank SC, Ordiz A, Gosselin J, Hertel A, Kindberg J, Leclerc M, Pelletier F, Steyaert SMJG, Støen OG, Van de Walle J, Zedrosser A, Swenson JE. Indirect effects of bear hunting: a review from Scandinavia. URSUS 2017. [DOI: 10.2192/ursu-d-16-00028.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Shane C. Frank
- Faculty of Arts and Sciences, Department of Environmental and Health Studies, University College of Southeast Norway, NO-3800 Bø i Telemark, Norway
| | - Andrés Ordiz
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway
| | - Jacinthe Gosselin
- Départment de Biologie, Canada Research Chair in Evolutionary Demography, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Anne Hertel
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway
| | - Jonas Kindberg
- Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
- Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden
| | - Martin Leclerc
- Départment de Biologie, Canada Research Chair in Evolutionary Demography, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Fanie Pelletier
- Départment de Biologie, Canada Research Chair in Evolutionary Demography, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Sam M. J. G. Steyaert
- Faculty of Arts and Sciences, Department of Environmental and Health Studies, University College of Southeast Norway, NO-3800 Bø i Telemark, Norway
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway
| | - Ole-Gunnar Støen
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway
- Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
| | - Joanie Van de Walle
- Départment de Biologie, Canada Research Chair in Evolutionary Demography, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Andreas Zedrosser
- Faculty of Arts and Sciences, Department of Environmental and Health Studies, University College of Southeast Norway, NO-3800 Bø i Telemark, Norway
- Institute for Wildlife Biology and Game Management, University for Natural Resources and Life Sciences, Vienna, Gregor Mendel Str. 33, A-1180 Vienna, Austria
| | - Jon E. Swenson
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway
- Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
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20
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Douhard M. Offspring sex ratio in mammals and the Trivers-Willard hypothesis: In pursuit of unambiguous evidence. Bioessays 2017; 39. [DOI: 10.1002/bies.201700043] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Mathieu Douhard
- Département de Biologie; Université de Sherbrooke; Sherbrooke Québec Canada
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21
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Cameron EZ, Edwards AM, Parsley LM. Developmental sexual dimorphism and the evolution of mechanisms for adjustment of sex ratios in mammals. Ann N Y Acad Sci 2016; 1389:147-163. [PMID: 27862006 DOI: 10.1111/nyas.13288] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Revised: 09/28/2016] [Accepted: 10/05/2016] [Indexed: 12/15/2022]
Abstract
Sex allocation theory predicts biased offspring sex ratios in relation to local conditions if they would maximize parental lifetime reproductive return. In mammals, the extent of the birth sex bias is often unpredictable and inconsistent, leading some to question its evolutionary significance. For facultative adjustment of sex ratios to occur, males and females would need to be detectably different from an early developmental stage, but classic sexual dimorphism arises from hormonal influences after gonadal development. Recent advances in our understanding of early, pregonadal sexual dimorphism, however, indicate high levels of dimorphism in gene expression, caused by chromosomal rather than hormonal differences. Here, we discuss how such dimorphism would interact with and link previously hypothesized mechanisms for sex-ratio adjustment. These differences between males and females are sufficient for offspring sex both to be detectable to parents and to provide selectable cues for biasing sex ratios from the earliest stages. We suggest ways in which future research could use the advances in our understanding of sexually dimorphic developmental physiology to test the evolutionary significance of sex allocation in mammals. Such an approach would advance our understanding of sex allocation and could be applied to other taxa.
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Affiliation(s)
- Elissa Z Cameron
- School of Biological Sciences, University of Tasmania, Hobart, Australia.,School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Amy M Edwards
- School of Biological Sciences, University of Tasmania, Hobart, Australia
| | - Laura M Parsley
- School of Biological Sciences, University of Tasmania, Hobart, Australia
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22
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Edwards AM, Cameron EZ, Pereira JC, Wapstra E, Ferguson-Smith MA, Horton SR, Thomasson K. Gestational experience alters sex allocation in the subsequent generation. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160210. [PMID: 27493776 PMCID: PMC4968468 DOI: 10.1098/rsos.160210] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 06/08/2016] [Indexed: 06/06/2023]
Abstract
Empirical tests of adaptive maternal sex allocation hypotheses have presented inconsistent results in mammals. The possibility that mothers are constrained in their ability to adjust sex ratios could explain some of the remaining variation. Maternal effects, the influence of the maternal phenotype or genotype on her developing offspring, may constrain sex allocation through physiological changes in response to the gestational environment. We tested if maternal effects constrain future parental sex allocation through a lowered gestational stress environment in laboratory mice. Females that experienced lowered stress as embryos in utero gave birth to female-biased litters as adults, with no change to litter size. Changes in offspring sex ratio was linked to peri-conceptual glucose, as those females that had increasing blood glucose peri-conceptionally gave birth to litters with a higher male to female sex ratio. There was, however, no effect of the lowered prenatal stress for developing male embryos and their sperm sex ratio when adult. We discuss the implications of maternal effects and maternal stress environment on the lifelong physiology of the offspring, particularly as a constraint on later maternal sex allocation.
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Affiliation(s)
- A. M. Edwards
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - E. Z. Cameron
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - J. C. Pereira
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
- Cytocell Ltd., Cambridge Technopark, Newmarket Road, Cambridge, UK
| | - E. Wapstra
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | | | - S. R. Horton
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - K. Thomasson
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia
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