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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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Dias PAD, Montero Domínguez IL, Rangel Negrín A. Factors influencing infant sex ratio in howler monkeys (Alouatta spp.): A literature review and analysis. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 172:48-57. [PMID: 32141069 DOI: 10.1002/ajpa.24035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 02/11/2020] [Accepted: 02/19/2020] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Frequency-dependent selection is expected to maintain infant sex ratios around parity over evolutionary time. However, over ecological time periods, infant sex ratios vary, and it has been proposed that this variation may reflect adaptive processes. In primates, there are consistent patterns of variation in infant sex ratios, although their adaptive significance remains contentious. In addition to design issues, contrasting results could have derived across primates from variation in the fitness benefits accrued through sons or daughters associated with the specific social, ecological, and demographic context of populations. Thus, different sex allocation tactics could occur within species over time and space. METHODS We reviewed the literature to describe variation in infant sex ratio in howler monkeys (genus Alouatta) and to examine whether such a variation could be associated with adaptive sex allocation. We found 26 studies that provided data for this review. These studies yielded 96 infant sex reports, corresponding to 1,477 sexed infants. RESULTS Infant sex ratio across howler monkey species tends to parity, but females produce more sons under high group densities and more daughters when rainfall increases. DISCUSSION Based on these results, as well as on information on howler monkey dispersal patterns, demography, and within-group genetic relatedness, we speculate that, depending on population growth stage, sex allocation is explained by (a) local resource enhancement, that is, more cooperative philopatric daughters are produced when populations are growing; and (b) local resource competition, that is, more dispersing sons are produced when populations are saturated. Thus, there is evidence suggestive of adaptive variation in infant sex ratios in howler monkeys.
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Affiliation(s)
- Pedro A D Dias
- Primate Behavioral Ecology Lab, Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz, Mexico
| | - Irma L Montero Domínguez
- Primate Behavioral Ecology Lab, Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz, Mexico
| | - Ariadna Rangel Negrín
- Primate Behavioral Ecology Lab, Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz, Mexico
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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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4
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The Adaptive Sex in Stressful Environments. Trends Ecol Evol 2019; 34:628-640. [PMID: 30952545 DOI: 10.1016/j.tree.2019.02.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 02/18/2019] [Accepted: 02/19/2019] [Indexed: 01/10/2023]
Abstract
The impact of early stress on juvenile development has intrigued scientists for decades, but the adaptive significance of such effects remains an ongoing debate. This debate has largely ignored some characteristics of the offspring, such as their sex, despite strong evolutionary and demographic implications of sex-ratio variation. We review recent studies that examine associations between glucocorticoids (GCs), the main class of stress hormones, and offspring sex. Whereas exposure to GCs at around the time of sex determination in fish consistently produces males, the extent and direction of sex-ratio bias in response to stress vary in reptiles, birds, and mammals. We propose proximate and ultimate explanations for most of these trends.
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Edwards AM, Cameron EZ, Wapstra E, McEvoy J. Maternal effects obscure condition-dependent sex allocation in changing environments. ROYAL SOCIETY OPEN SCIENCE 2019; 6:181885. [PMID: 31183124 PMCID: PMC6502394 DOI: 10.1098/rsos.181885] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 03/05/2019] [Indexed: 06/09/2023]
Abstract
Climate change increases environmental fluctuations which thereby impact population demography. Species with temperature-dependent sex determination may experience more extreme sex ratio skews, but this has not been considered in species with chromosomally determined sex. However, anticipatory maternal effects cause lifelong physiological changes impacting sex ratios. Here we show, in mice, that more sons were born to mothers in good condition when their breeding environment matched their gestational environment, consistent with theoretical predictions, but mothers in mismatched environments have no condition-sex ratio relationship. Thus, the predicted effect of condition on sex ratio was obscured by maternal effects when the environment changed. This may explain extreme sex ratio skews in reintroduced or translocated populations, and sex ratio skews may become more common and less predictable with accelerating environmental change.
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Affiliation(s)
- A. M. Edwards
- Department of Ecology, Environment and Evolution, La Trobe University, Bundoora, Victoria 3086, Australia
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
| | - E. Z. Cameron
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
- School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
| | - E. Wapstra
- Department of Ecology, Environment and Evolution, La Trobe University, Bundoora, Victoria 3086, Australia
| | - J. McEvoy
- Department of Ecology, Environment and Evolution, La Trobe University, Bundoora, Victoria 3086, Australia
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Rangel-Negrín A, Coyohua-Fuentes A, Canales-Espinosa D, Chavira-Ramírez DR, Dias PAD. Maternal glucocorticoid levels affect sex allocation in black howler monkeys. J Zool (1987) 2017. [DOI: 10.1111/jzo.12503] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- A. Rangel-Negrín
- Primate Behavioral Ecology Lab; Instituto de Neuroetología; Universidad Veracruzana; Xalapa Veracruz México
| | - A. Coyohua-Fuentes
- Primate Behavioral Ecology Lab; Instituto de Neuroetología; Universidad Veracruzana; Xalapa Veracruz México
| | - D. Canales-Espinosa
- Primate Behavioral Ecology Lab; Instituto de Neuroetología; Universidad Veracruzana; Xalapa Veracruz México
| | - D. R. Chavira-Ramírez
- Belisario Domínguez Sección XVI; Instituto Nacional de Ciencias Médicas y Nutrición “Salvador Zubirán”; Tlalpan México
| | - P. A. D. Dias
- Primate Behavioral Ecology Lab; Instituto de Neuroetología; Universidad Veracruzana; Xalapa Veracruz México
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SALAZAR DA, FONTÚRBEL FE. Beyond habitat structure: Landscape heterogeneity explains the monito del monte (Dromiciops gliroides) occurrence and behavior at habitats dominated by exotic trees. Integr Zool 2016; 11:413-21. [DOI: 10.1111/1749-4877.12198] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daniela A. SALAZAR
- Departamento de Ciencias Ecológicas, Facultad de Ciencias; Universidad de Chile; Santiago Chile
| | - Francisco E. FONTÚRBEL
- Instituto de Biología, Facultad de Ciencias; Pontificia Universidad Católica de Valparaíso; Valparaíso Chile
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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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Schwanz LE, Robert KA. Costs of Rearing the Wrong Sex: Cross-Fostering to Manipulate Offspring Sex in Tammar Wallabies. PLoS One 2016; 11:e0146011. [PMID: 26849128 PMCID: PMC4743941 DOI: 10.1371/journal.pone.0146011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 12/12/2015] [Indexed: 11/19/2022] Open
Abstract
Sex allocation theory assumes that offspring sex (son vs. daughter) has consequences for maternal fitness. The most compelling experiment to test this theory would involve manipulating offspring sex and measuring the fitness consequences of having the "wrong" sex. Unfortunately, the logistical challenges of such an experiment limit its application. In tammar wallabies (Macropus eugenii), previous evidence suggests that mothers in good body condition are more likely to produce sons compared to mothers in poor condition, in support of the Trivers-Willard Hypothesis (TW) of condition-dependent sex allocation. More recently, we have found in our population of tammar wallabies that females with seemingly poor access to resources (based on condition loss over the dry summer) are more likely to produce sons, consistent with predictions from the Local Resource Competition (LRC) hypothesis, which proposes that production of sons or daughters is driven by the level of potential competition between mothers and philopatric daughters. We conducted a cross-fostering experiment in free-ranging tammar wallabies to disassociate the effects of rearing and birthing offspring of each sex. This allowed us to test the prediction of the LRC hypothesis that rearing daughters reduces the future direct fitness of mothers post-weaning and the prediction of the TW hypothesis that rearing sons requires more energy during lactation. Overall, we found limited costs to the mother of rearing the "wrong" sex, with switching of offspring sex only reducing the likelihood of a mother having a pouch young the following year. Thus, we found some support for both hypotheses in that rearing an unexpected son or an unexpected daughter both lead to reduced future maternal fitness. The study suggests that there may be context-specific costs associated with rearing the "wrong" sex.
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Affiliation(s)
- Lisa E. Schwanz
- School of Marine and Tropical Biology, James Cook University, Townsville, QLD, Australia
- Institute for Applied Ecology, University of Canberra, Canberra, ACT, Australia
| | - Kylie A. Robert
- School of Animal Biology, The University of Western Australia, Perth, WA, Australia
- Department of Ecology, Environment and Evolution, La Trobe University, Bundoora, VIC, Australia
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10
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Variable flight distance to resources results in changing sex allocation decisions, Megachile rotundata. Behav Ecol Sociobiol 2015. [DOI: 10.1007/s00265-015-2043-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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