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Gómez‐López G, Sanz‐Aguilar A, Carrete M, Arrondo E, Benítez JR, Ceballos O, Cortés‐Avizanda A, de Pablo F, Donázar JA, Frías Ó, Gangoso L, García‐Alfonso M, González JL, Grande JM, Serrano D, Tella JL, Blanco G. Insularity determines nestling sex ratio variation in Egyptian vulture populations. Ecol Evol 2023; 13:e10371. [PMID: 37529590 PMCID: PMC10385291 DOI: 10.1002/ece3.10371] [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: 04/12/2023] [Revised: 07/04/2023] [Accepted: 07/11/2023] [Indexed: 08/03/2023] Open
Abstract
Variation in offspring sex ratio, particularly in birds, has been frequently studied over the last century, although seldom using long-term monitoring data. In raptors, the cost of raising males and females is not equal, and several variables have been found to have significant effects on sex ratio, including food availability, parental age, and hatching order. Sex ratio differences between island populations and their mainland counterparts have been poorly documented, despite broad scientific literature on the island syndrome reporting substantial differences in population demography and ecology. Here, we assessed individual and environmental factors potentially affecting the secondary sex ratio of the long-lived Egyptian vulture Neophron percnopterus. We used data collected from Spanish mainland and island populations over a ca. 30-year period (1995-2021) to assess the effects of insularity, parental age, breeding phenology, brood size, hatching order, type of breeding unit (pairs vs. trios), and spatial and temporal variability on offspring sex ratio. No sex bias was found at the population level, but two opposite trends were observed between mainland and island populations consistent with the island syndrome. Offspring sex ratio was nonsignificantly female-biased in mainland Spain (0.47, n = 1112) but significantly male-biased in the Canary Islands (0.55, n = 499), where a male-biased mortality among immatures could be compensating for offspring biases and maintaining a paired adult sex ratio. Temporal and spatial variation in food availability might also have some influence on sex ratio, although the difficulties in quantifying them preclude us from determining the magnitude of such influence. This study shows that insularity influences the offspring sex ratio of the Egyptian vulture through several processes that can affect island and mainland populations differentially. Our research contributes to improving our understanding of sex allocation theory by investigating whether sex ratio deviations from parity are possible as a response to changing environments comprised by multiple and complexly interrelated factors.
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Affiliation(s)
- Guillermo Gómez‐López
- Department of Evolutionary Ecology, National Museum of Natural SciencesSpanish National Research CouncilMadridSpain
- Department of Biodiversity, Ecology and Evolution, Faculty of BiologyComplutense University of MadridMadridSpain
| | - Ana Sanz‐Aguilar
- Animal Demography and Ecology GroupInstitut Mediterrani d'Estudis Avançats, Spanish National Research CouncilMallorcaSpain
- Applied Zoology and Conservation GroupUniversitat de les Illes BalearsPalmaSpain
| | - Martina Carrete
- Department of Physical, Chemical and Natural SystemsPablo de Olavide UniversitySevillaSpain
| | - Eneko Arrondo
- Department of ZoologyUniversity of GranadaGranadaSpain
- Department of Applied BiologyMiguel Hernández UniversityElcheSpain
| | - José Ramón Benítez
- Department of BiodiversityAgencia de Medioambiente y Agua, Junta de AndalucíaSevillaSpain
| | | | - Ainara Cortés‐Avizanda
- Department of Plant Biology and EcologyUniversity of SevilleSevillaSpain
- Department of Conservation BiologyDoñana Biological Station, Spanish National Research CouncilSevillaSpain
| | - Félix de Pablo
- Department of Environment and Biosphere ReserveConsell Insular de Menorca, PlazaMaóSpain
| | - José Antonio Donázar
- Department of Conservation BiologyDoñana Biological Station, Spanish National Research CouncilSevillaSpain
| | - Óscar Frías
- Department of Physical, Chemical and Natural SystemsPablo de Olavide UniversitySevillaSpain
| | - Laura Gangoso
- Department of Biodiversity, Ecology and Evolution, Faculty of BiologyComplutense University of MadridMadridSpain
| | - Marina García‐Alfonso
- Department of Conservation BiologyDoñana Biological Station, Spanish National Research CouncilSevillaSpain
| | - José Luis González
- Department of Evolutionary Ecology, National Museum of Natural SciencesSpanish National Research CouncilMadridSpain
| | | | - David Serrano
- Department of Conservation BiologyDoñana Biological Station, Spanish National Research CouncilSevillaSpain
| | - José Luis Tella
- Department of Conservation BiologyDoñana Biological Station, Spanish National Research CouncilSevillaSpain
| | - Guillermo Blanco
- Department of Evolutionary Ecology, National Museum of Natural SciencesSpanish National Research CouncilMadridSpain
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2
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Facultative and persistent offspring sex-ratio bias in relation to the social environment in cooperatively breeding red-winged fairy-wrens (Malurus elegans). Behav Ecol Sociobiol 2022. [DOI: 10.1007/s00265-022-03221-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Abstract
Females should facultatively bias offspring sex ratio when fitness returns vary among sexes. In cooperative breeders, where individuals help raise others’ young, overproducing the philopatric sex will be adaptive when helpers are absent, whereas overproducing the dispersive sex may be adaptive to reduce intrasexual competition. Thus, fitness returns are expected to vary with the social environment. However, any offspring sex-ratio biases may also result from consistent among-female differences (e.g. quality) and/or environmental variables (e.g. food availability). Yet, few studies have disentangled facultative from persistent biases. We investigated offspring sex-ratio biases in relation to the social environment in cooperatively breeding red-winged fairy-wrens (Malurus elegans). Repeated observations of the same females over nine years allowed for disentanglement of facultative from persistent biases. Females without help did not overproduce daughters, despite female helpers being associated with higher fledgling survival (resource enhancement hypothesis). Instead, females without helpers facultatively overproduced sons —the slower dispersing sex— thereby ensuring long-term helper availability. Furthermore, offspring sex ratio was not biased towards the rarer sex of helpers present in the group or population (resource competition hypothesis). However, females with sex-biased helping produced similarly skewed offspring sex ratios. This among-female association may not be surprising, because helpers are previous seasons’ offspring. Thus, in addition to facultative responses to prevailing social conditions, we found evidence for persistent biases among females. This could potentially explain previous evidence for resource competition/enhancement that have typically been interpreted as facultative responses, highlighting the need for a within-female approach to better understand the adaptiveness of sex-ratio biases.
Significance statement
Under certain conditions, females may benefit from producing a biased offspring sex ratio, but evidence for such effects in vertebrates is weak and inconsistent. Here, using observations of the same females under different social conditions, we show that cooperatively breeding red-winged fairy-wrens facultatively biased offspring sex ratio towards sons when living in pairs, thereby ensuring the availability of a workforce to assist in raising future offspring. However, biased offspring sex ratio patterns may also be the result of consistent differences among females. Indeed, we also found evidence for such patterns and suggest that this could be an explanation for previous findings which are often interpreted as facultative responses.
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Khwaja N, Hatchwell BJ, Freckleton RP, Green JP. Sex Allocation Patterns across Cooperatively Breeding Birds Do Not Support Predictions of the Repayment Hypothesis. Am Nat 2017; 190:547-556. [PMID: 28937820 DOI: 10.1086/693532] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The repayment hypothesis predicts that reproductive females in cooperative breeding systems overproduce the helping sex. Thanks to well-documented examples of this predicted sex ratio bias, repayment has been considered an important driver of variation in sex allocation patterns. Here we test this hypothesis using data on population brood sex ratios and facultative sex allocation from 28 cooperatively breeding bird species. We find that biased sex ratios of helpers do not correlate with production biases in brood sex ratios, contrary to predictions. We also test whether females facultatively produce the helping sex in response to a deficiency of help (i.e., when they have fewer or no helpers). Although this is observed in a few species, it is not a significant trend overall, with a mean effect size close to zero. We conclude that, surprisingly, repayment does not appear to be a widespread influence on sex ratios in cooperatively breeding birds. We discuss possible explanations for our results and encourage further examination of the repayment model.
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Bell SC, Owens IPF, Lord AM. Quality of breeding territory mediates the influence of paternal quality on sex ratio bias in a free-living bird population. Behav Ecol 2013. [DOI: 10.1093/beheco/art112] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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5
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Badyaev AV. "Homeostatic hitchhiking": a mechanism for the evolutionary retention of complex adaptations. Integr Comp Biol 2013; 53:913-22. [PMID: 23868466 DOI: 10.1093/icb/ict084] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The complexity of organismal organization channels and accommodates novel genomic and developmental modifications. Here, I extend this perspective to suggest that emergent processes that dominate homeostasis-co-option, re-use, and recombination of accumulated elements-can create configurations and dependencies among these elements that strongly reduce the number of evolutionary steps needed for the evolution of precise novel adaptations. Evolutionary retention and environmental matching of such configurations are further facilitated when they include elements of homeostasis that are responsive to particular environmental cues. I apply this perspective to the study of evolution of sex-biased egg-laying in birds, a phenomenon that combines precision, complexity, context-dependency, and reversibility. I show that homeostatic hitchhiking can overcome the main difficulty in the evolution of this adaptation-the perceived necessity of de novo co-evolution of oogenesis, sex-determination, and order of ovulation in each environmental context-something that would require unrealistic expectations of evolutionary rates and population sizes and is not a desirable outcome for a process that needs to retain substantial environmental sensitivity. First, I explain the rationale behind the homeostatic-hitchhiking hypothesis and outline its predictions specifically for studies of sex-bias in order of egg-laying. Second, I show that a combination of self-regulatory and emergent processes and ubiquitous re-use of conserved growth factors make oogenesis particularly amendable to homeostatic hitchhiking. Third, I review empirical evidence for this mechanism in the rapid evolution of adaptive sex-biased order of egg-laying that accompanied colonization of North America by the house finch (Carpodacus mexicanus).
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Affiliation(s)
- Alexander V Badyaev
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
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6
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Stubblefield JW, Orzack SH. Resource transfers and evolution: helpful offspring and sex allocation. Theor Popul Biol 2013; 83:64-81. [PMID: 23164634 PMCID: PMC3590114 DOI: 10.1016/j.tpb.2012.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 09/13/2012] [Accepted: 09/19/2012] [Indexed: 11/24/2022]
Abstract
In some vertebrates, offspring help their parents produce additional offspring. Often individuals of one sex are more likely to become "helpers at the nest". We analyze how such sex-biased offspring helping can influence sex-ratio evolution. It is essential to account for age-structure because the sex ratios of early broods influence how much help is available for later broods; previous authors have not correctly accounted for this fact. When each female produces the same sex ratio in all broods (as assumed in all previous analyses of sex-biased helping), the optimal investment strategy is biased towards the more-helpful sex. When a female has facultative control over the sex ratio in each brood and each helper of a given sex increases the resource available for offspring production by a fixed amount, the optimal strategy is to produce only the more-helpful sex in early broods and only the less-helpful sex in later broods. When there are nonlinear returns from helping, i.e., each helper increases the amount of resource available for reproduction by an amount dependent upon the number of helpers, the optimal strategy is to maximize resource accrual from helping in early broods (which may involve the production of both sexes) and then switch to the exclusive production of the less-helpful sex in later broods. The population sex ratio is biased towards the more-helpful sex regardless of whether the sex ratio is fixed or age-dependent. When fitness returns from helping exhibit environmental patchiness, females are selected to produce only males on some patches and only females on others, and the population sex ratio may be biased in either direction. We discuss our results in light of empirical information on offspring helping, and we show via meta-analysis that there is no support for the claim of Griffin et al. [Griffin, A.S., Sheldon, B.C., West, S.A., 2005. Cooperative breeders adjust offspring sex ratios to produce helpful helpers. Amer. Nat. 166, 628-632] that parents produce more of the helpful sex when that sex is rare or absent.
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7
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Cooperatively breeding carrion crows adjust offspring sex ratio according to group composition. Behav Ecol Sociobiol 2012. [DOI: 10.1007/s00265-012-1375-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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8
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Pinson SE, Wilson JL, Navara KJ. Elevated testosterone during meiotic segregation stimulates laying hens to produce more sons than daughters. Gen Comp Endocrinol 2011; 174:195-201. [PMID: 21925503 DOI: 10.1016/j.ygcen.2011.08.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 08/22/2011] [Accepted: 08/24/2011] [Indexed: 11/25/2022]
Abstract
Biases in avian sex ratios have been documented in relation to a variety of social and environmental conditions. Previous studies suggest that treatment with hormones can stimulate females to manipulate offspring sex, and that this effect occurs before ovulation. For example, acute and chronic treatments with testosterone stimulated significant skews towards male offspring. Hormones may act by influencing which sex chromosome is donated by the heterogametic female bird into the oocyte. However, it is difficult to pinpoint when effects of testosterone on offspring sex occurred in previous experiments because testosterone treatments were given either chronically over the entire period of follicular development or many hours before the critical period of chromosome segregation. We injected laying hens with testosterone injections 5 h prior to ovulation to target this critical period and quantified the sexes of the subsequently ovulated eggs. We hypothesized that an injection of testosterone coincident with segregation of sex chromosomes would stimulate hens to produce more male than female offspring. As hypothesized, hens injected with testosterone produced a significant bias towards male offspring compared to controls, nearly 70%. These results suggest that acute testosterone elevation during meiotic segregation may mediate skews in avian primary sex ratios.
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Affiliation(s)
- Sara E Pinson
- Department of Poultry Science, University of Georgia, Athens, GA 30602, USA.
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9
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Abstract
In cooperatively breeding species, the fitness consequences of producing sons or daughters depend upon the fitness impacts of positive (repayment hypothesis) and negative (local competition hypothesis) social interactions among relatives. In this study, we examine brood sex allocation in relation to the predictions of both the repayment and the local competition hypotheses in the cooperatively breeding long-tailed tit Aegithalos caudatus. At the population level, we found that annual brood sex ratio was negatively related to the number of male survivors across years, as predicted by the local competition hypothesis. At an individual level, in contrast to predictions of the repayment hypothesis, there was no evidence for facultative control of brood sex ratio. However, immigrant females produced a greater proportion of sons than resident females, a result consistent with both hypotheses. We conclude that female long-tailed tits make adaptive decisions about brood sex allocation.
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Affiliation(s)
- K-B Nam
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.
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10
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Kingma SA, Hall ML, Peters A. No evidence for offspring sex-ratio adjustment to social or environmental conditions in cooperatively breeding purple-crowned fairy-wrens. Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-1133-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Varian-Ramos CW, Karubian J, Talbott V, Tapia I, Webster MS. Offspring sex ratios reflect lack of repayment by auxiliary males in a cooperatively breeding passerine. Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-0912-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Badyaev AV, Young RL, Hill GE, Duckworth RA. Evolution of sex-biased maternal effects in birds. IV. Intra-ovarian growth dynamics can link sex determination and sex-specific acquisition of resources. J Evol Biol 2008; 21:449-60. [PMID: 18205775 DOI: 10.1111/j.1420-9101.2007.01498.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The evolutionary importance of maternal effects is determined by the interplay of maternal adaptations and strategies, offspring susceptibility to these strategies, and the similarity of selection pressures between the two generations. Interaction among these components, especially in species where males and females differ in the costs and requirements of growth, limits inference about the evolution of maternal strategies from their expression in the offspring phenotype alone. As an alternative approach, we examine divergence in the proximate mechanisms underlying maternal effects across three house finch populations with contrasting patterns of sex allocation: an ancestral population that shows no sex-biased ovulation, and two recently established populations at the northern and southern boundaries of the species range that have opposite sequences of ovulation of male and female eggs. For each population, we examined how oocyte acquisition of hormones, carotenoids and vitamins was affected by oocyte growth and overlap with the same and opposite sexes. Our results suggest that sex-specific acquisition of maternal resources and sex determination of oocytes are linked in this system. We report that acquisition of testosterone by oocytes that become males was not related to growth duration, but instead covaried with temporal exposure to steroids and overlap with other male oocytes. In female oocytes, testosterone acquisition increased with the duration of growth and overlap with male oocytes, but decreased with overlap with female oocytes. By contrast, acquisition of carotenoids and vitamins was mostly determined by organism-wide partitioning among oocytes and oocyte-specific patterns of testosterone accumulation, and these effects did not differ between the sexes. These results provide important insights into three unresolved phenomena in the evolution of maternal effects - (i) the evolution of sex-specific maternal allocation in species with simultaneously developing neonates of both sexes; (ii) the link between sex determination and sex-specific acquisition of maternal products; and (iii) the evolution of context-dependent modulation of maternal effects.
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Affiliation(s)
- A V Badyaev
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA.
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13
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Walguarnery JW. Do Anoles (Sauria: Polychrotidae: Genus Anolis) Alternate the Sex of Successive Offspring. COPEIA 2007. [DOI: 10.1643/0045-8511(2007)7[829:daspga]2.0.co;2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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14
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Abe J, Kamimura Y, Shimada M. Sex ratio schedules in a dynamic game: the effect of competitive asymmetry by male emergence order. Behav Ecol 2007. [DOI: 10.1093/beheco/arm083] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Sex-biases in the hatching sequence of cooperatively breeding apostlebirds Struthidea cinerea. Evol Ecol 2007. [DOI: 10.1007/s10682-007-9163-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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16
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Uller T. Sex-specific sibling interactions and offspring fitness in vertebrates: patterns and implications for maternal sex ratios. Biol Rev Camb Philos Soc 2006; 81:207-17. [PMID: 16677432 DOI: 10.1017/s1464793105006962] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Revised: 11/04/2005] [Accepted: 11/04/2005] [Indexed: 11/06/2022]
Abstract
Vertebrate sex ratios are notorious for their lack of fit to theoretical models, both with respect to the direction and the magnitude of the sex ratio adjustment. The reasons for this are likely to be linked to simplifying assumptions regarding vertebrate life histories. More specifically, if the sex ratio adjustment itself influences offspring fitness, due to sex-specific interactions among offspring, this could affect optimal sex ratios. A review of the literature suggests that sex-specific sibling interactions in vertebrates result from three major causes: (i) sex asymmetries in competitive ability, for example due to sexual dimorphism, (ii) sex-specific cooperation or helping, and (iii) sex asymmetries in non-competitive interactions, for example steroid leakage between fetuses. Incorporating sex-specific sibling interactions into a sex ratio model shows that they will affect maternal sex ratio strategies and, under some conditions, can repress other selection pressures for sex ratio adjustment. Furthermore, sex-specific interactions could also explain patterns of within-brood sex ratio (e.g. in relation to laying order). Failure to take sex-specific sibling interactions into account could partly explain the lack of sex ratio adjustment in accordance with theoretical expectations in vertebrates, and differences among taxa in sex-specific sibling interactions generate predictions for comparative and experimental studies.
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Affiliation(s)
- Tobias Uller
- School of Biological Sciences, University of Wollongong, NSW 2522, Australia.
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17
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BLANCO GUILLERMO, FRÍAS OSCAR, MARTÍNEZ JAVIER, LEMUS JESÚSA, MERINO RUBEN, JIMÉNEZ BEGOÑA. Sex and rank in competitive brood hierarchies influence stress levels in nestlings of a sexually dimorphic bird. Biol J Linn Soc Lond 2006. [DOI: 10.1111/j.1095-8312.2006.00625.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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18
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Badyaev AV, Oh KP, Mui R. Evolution of sex-biased maternal effects in birds: II. Contrasting sex-specific oocyte clustering in native and recently established populations. J Evol Biol 2006; 19:909-21. [PMID: 16674587 DOI: 10.1111/j.1420-9101.2005.01041.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In species that produce broods of multiple offspring, parents need to partition resources among simultaneously growing neonates that often differ in growth requirements. In birds, multiple ovarian follicles develop inside the female at the same time, resulting in a trade-off of resources among them and potentially limiting maternal ability for sex-specific allocation. We compared resource acquisition among oocytes in relation to their future sex and ovulation order in two populations of house finches with contrasting sex-biased maternal strategies. In a native Arizona population, where mothers do not bias offspring sex in relation to ovulation order, the male and female oocytes did not show sex-specific trade-offs of resources during growth and there was no evidence for spatial or temporal segregation of male and female oocytes in the ovary. In contrast, in a recently established Montana population where mothers strongly bias offspring sex in relation to ovulation order, we found evidence for both intra-sexual trade-offs among male and female oocytes and sex-specific clustering of oocytes in the ovary. We discuss the importance of sex-specific resource competition among offspring for the evolution of sex-ratio adjustment and sex-specific maternal resource allocation.
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Affiliation(s)
- A V Badyaev
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721-0088, USA.
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Badyaev AV, Schwabl H, Young RL, Duckworth RA, Navara KJ, Parlow AF. Adaptive sex differences in growth of pre-ovulation oocytes in a passerine bird. Proc Biol Sci 2006; 272:2165-72. [PMID: 16188605 PMCID: PMC1559945 DOI: 10.1098/rspb.2005.3194] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Maternal modification of offspring sex in birds has strong fitness consequences, however the mechanisms by which female birds can bias sex of their progeny in close concordance with the environment of breeding are not known. In recently established populations of house finches (Carpodacus mexicanus), breeding females lay a sex-biased sequence of eggs when ambient temperature causes early onset of incubation. We studied the mechanisms behind close association of incubation and sex-determination strategies in this species and discovered that pre-ovulation oocytes that produce males and females differed strongly in the temporal patterns of proliferation and growth. In turn, sex-specific exposure of oocytes to maternal secretion of prolactin and androgens produced distinct accumulation of maternal steroids in oocyte yolks in relation to oocyte proliferation order. These findings suggest that sex difference in oocyte growth and egg-laying sequence is an adaptive outcome of hormonal constraints imposed by the overlap of early incubation and oogenesis in this population, and that the close integration of maternal incubation, oocytes' sex-determination and growth might be under control of the same hormonal mechanism. We further document that population establishment and the evolution of these maternal strategies is facilitated by their strong effects on female and offspring fitness in a recently established part of the species range.
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Affiliation(s)
- Alexander V Badyaev
- Department of Ecology & Evolutionary Biology, University of Arizona, Tucson, AZ 85721-0088, USA.
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20
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Korsten P, Lessells C(KM, Mateman AC, van der Velde M, Komdeur J. Primary sex ratio adjustment to experimentally reduced male UV attractiveness in blue tits. Behav Ecol 2006. [DOI: 10.1093/beheco/arj061] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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21
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Griffin AS, Sheldon BC, West SA. Cooperative Breeders Adjust Offspring Sex Ratios to Produce Helpful Helpers. Am Nat 2005; 166:628-32. [PMID: 16224727 DOI: 10.1086/491662] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2005] [Accepted: 06/17/2005] [Indexed: 11/03/2022]
Abstract
Whether birds and mammals adaptively adjust their offspring sex ratios in response to their environment is much debated. A source of confusion is that different studies show different patterns, with sex ratio adjustment appearing to occur in some cases but not others. The extent to which this reflects interesting biological variation due to differences in the underlying selective forces, as opposed to statistical noise, is not clear. Cooperatively breeding species offer an opportunity to address this problem because the strength of selection on sex ratio adjustment can be estimated. When helping behavior is sex dependent, parents are predicted to overproduce the helping sex when this sex is rare or absent. We show here that the extent of this behavior depends on the benefit that helpers bring to parents: there is greater sex ratio adjustment when helpers bring larger benefits. Variable selection on sex ratio adjustment may thus explain variable empirical findings.
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Affiliation(s)
- Ashleigh S Griffin
- Institute of Evolutionary Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, United Kingdom
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22
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West SA, Shuker DM, Sheldon BC. SEX-RATIO ADJUSTMENT WHEN RELATIVES INTERACT: A TEST OF CONSTRAINTS ON ADAPTATION. Evolution 2005. [DOI: 10.1111/j.0014-3820.2005.tb01772.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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23
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West SA, Shuker DM, Sheldon BC. SEX-RATIO ADJUSTMENT WHEN RELATIVES INTERACT: A TEST OF CONSTRAINTS ON ADAPTATION. Evolution 2005. [DOI: 10.1554/04-158] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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24
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Allainé D. Sex ratio variation in the cooperatively breeding alpine marmot Marmota marmota. Behav Ecol 2004. [DOI: 10.1093/beheco/arh105] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Abstract
The aim of this review is to consider the potential mechanisms birds may use to manipulate the sex of their progeny, and the possible role played by maternal hormones. Over the past few years there has been a surge of reports documenting the ability of birds to overcome the rigid process of chromosomal sex determination. However, while many of these studies leave us in little doubt that mechanisms allowing birds to achieve this feat do exist, we are only left with tantalizing suggestions as to what the precise mechanism or mechanisms may be. The quest to elucidate them is made no easier by the fact that a variety of environmental conditions have been invoked in relation to sex manipulation, and there is no reason to assume that any particular mechanism is conserved among the vast diversity of species that can achieve it. In fact, a number of intriguing proposals have been put forward. We begin by briefly reviewing some of the most recent examples of this phenomenon before highlighting some of the more plausible mechanisms, drawing on recent work from a variety of taxa. In birds, females are the heterogametic sex and so non-Mendelian segregation of the sex chromosomes could conceivably be under maternal control. Another suggestion is that follicles that ultimately give rise to males and females grow at different rates. Alternatively, the female might selectively abort embryos or 'dump lay' eggs of a particular sex, deny certain ova a chance of ovulation, fertilization or zygote formation, or selectively provision eggs so that there is sex-specific embryonic mortality. The ideas outlined in this review provide good starting points for testing the hypotheses both experimentally (behaviourally and physiologically) and theoretically.
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Affiliation(s)
- Thomas W Pike
- Evolution and Behaviour Research Group, School of Biology, Henry Wellcome Building, University of Newcastle, Newcastle upon Tyne NE1 4HH, UK.
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Badyaev AV, Hill GE, Beck ML. Interaction between maternal effects: onset of incubation and offspring sex in two populations of a passerine bird. Oecologia 2003; 135:386-90. [PMID: 12721828 DOI: 10.1007/s00442-003-1203-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2002] [Accepted: 01/29/2003] [Indexed: 11/24/2022]
Abstract
Maternal phenotype and maternal environment can profoundly affect the phenotype and fitness of offspring. Yet the causes of variation in such maternal effects are rarely known. Embryos in avian eggs cannot develop without being incubated and this creates an opportunity for maternal control of duration and onset of offspring development. However, females might adjust the start of incubation (e.g., coincident with the first egg or delayed until after egg-laying) in response to environmental conditions that they experience at the time of breeding. We studied two populations of the house finch ( Carpodacus mexicanus) that breed at the climatic extremes of the species' geographical range (Montana and Alabama) and found that in both populations, the timing of incubation onset was closely associated with the bias in the sequence in which male and female eggs were laid within a clutch. When females started incubation with the first egg, they produced sons and daughters in highly biased sequence, when females delayed the onset of incubation until after the egg-laying, the sequence of sons and daughters was not biased. Because in both populations, onset of incubation was associated with the ambient temperature, these results emphasize that maternal effects on offspring can be influenced by ecological conditions experienced by parental generation.
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Affiliation(s)
- Alexander V Badyaev
- Department of Ecology & Evolutionary Biology, University of Arizona, AZ 85721, Tucson, USA.
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Badyaev AV, Beck ML, Hill GE, Whittingham LA. The evolution of sexual size dimorphism in the house finch. V. Maternal effects. Evolution 2003; 57:384-96. [PMID: 12683534 DOI: 10.1111/j.0014-3820.2003.tb00272.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The phenotype of a mother and the environment that she provides might differentially affect the phenotypes of her sons and daughters, leading to change in sexual size dimorphism. Whereas these maternal effects should evolve to accommodate the adaptations of both the maternal and offspring generations, the mechanisms by which this is accomplished are rarely known. In birds, females adjust the onset of incubation (coincident with the first egg or after all eggs are laid) in response to the environment during breeding, and thus, indirectly, determine the duration of offspring growth. In the two house finch (Carpodacus mexicanus) populations that breed at the extremes of the species' distribution (Montana and Alabama), females experience highly distinct climatic conditions during nesting. We show that in close association with these conditions, females adjusted jointly the onset of incubation and the sequence in which they produced male and female eggs and consequently modified the growth of sons and daughters. The onset of incubation in newly breeding females closely tracked ambient temperature in a pattern consistent with the maintenance of egg viability. Because of the very different climates in Montana and Alabama, females in these populations showed the opposite patterns of seasonal change in incubation onset and the opposite sex bias in egg-laying order. In females with breeding experience, incubation onset and sex bias in laying order were closely linked regardless of the climatic variation. In nests in which incubation began with the onset of egg laying, the first-laid eggs were mostly females in Montana, but mostly males in Alabama. Because in both populations, male, but not female, embryos grew faster when exposed to longer incubation, the sex-bias produced highly divergent sizes of male and female juveniles between the populations. Overall, the compensatory interaction between the onset of incubation and the sex-biased laying order achieved a compromise between maternal and offspring adaptations and contributed to rapid morphological divergence in sexual dimorphism between populations of the house finch breeding at the climatic extremes of the species range.
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Affiliation(s)
- Alexander V Badyaev
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA.
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Badyaev AV, Beck ML, Hill GE, Whittingham LA. THE EVOLUTION OF SEXUAL SIZE DIMORPHISM IN THE HOUSE FINCH. V. MATERNAL EFFECTS. Evolution 2003. [DOI: 10.1554/0014-3820(2003)057[0384:teossd]2.0.co;2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Badyaev AV, Hill GE, Whittingham LA. Population consequences of maternal effects: sex-bias in egg-laying order facilitates divergence in sexual dimorphism between bird populations. J Evol Biol 2002. [DOI: 10.1046/j.1420-9101.2002.00462.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Komdeur J, Magrath MJL, Krackow S. Pre-ovulation control of hatchling sex ratio in the Seychelles warbler. Proc Biol Sci 2002; 269:1067-72. [PMID: 12028765 PMCID: PMC1690984 DOI: 10.1098/rspb.2002.1965] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Females of some bird species have a high degree of control over the sex ratio of their offspring at laying. Although several mechanisms have been put forward to explain how females might control the sex of their eggs, virtually nothing is known. As females are the heterogametic sex in birds, adjustment of the clutch sex ratio could arise either by pre- or post-ovulation control mechanisms. The Seychelles warbler (Acrocephalus sechellensis) exhibits extreme adaptive egg sex ratio bias. Typically, warblers produce only single-egg clutches, but by translocating pairs to vacant habitat of very high quality, most females were induced to produce two-egg clutches. Overall, females skewed clutch sex ratios strongly towards daughters (86.6%). This bias was evident in the first egg, but critically, also in the second eggs laid a day apart, even when all absent, unhatched, or unsexed second eggs were assumed to be male. Although a bias in the first egg may arise through either pre- or post-ovulation mechanisms, the skew observed in second eggs could only arise through pre-ovulation control. Post-ovulation adjustment may also contribute to skewed hatchling sex ratios, but as sex-biased release of gametes is likely to be a more efficient process of control, pre-ovulation mechanisms may be the sole means of adjustment in this species. High fitness differentials between sons and daughters, as apparent in the Seychelles warblers, may be necessary for primary sex ratio adjustment to evolve.
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Affiliation(s)
- Jan Komdeur
- Zoological Laboratory, University of Groningen, PO Box 14, 9750 AA Haren, The Netherlands.
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BLANCO G, DÁVILA JA, SEPTIEM JALÓPEZ, RODRÍGUEZ R, MARTÍNEZ R. Sex-biased initial eggs favours sons in the slightly size-dimorphic Scops owl (Otus scops). Biol J Linn Soc Lond 2002. [DOI: 10.1111/j.1095-8312.2002.tb01709.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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