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Romano A, Romano M, Caprioli M, Costanzo A, Parolini M, Rubolini D, Saino N. Sex allocation according to multiple sexually dimorphic traits of both parents in the barn swallow (Hirundo rustica). J Evol Biol 2015; 28:1234-47. [PMID: 25913917 DOI: 10.1111/jeb.12650] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 04/21/2015] [Accepted: 04/23/2015] [Indexed: 01/10/2023]
Abstract
Parents should differentially invest in sons or daughters depending on the sex-specific fitness returns from male and female offspring. In species with sexually selected heritable male characters, highly ornamented fathers should overproduce sons, which will be more sexually attractive than sons of less ornamented fathers. Because of genetic correlations between the sexes, females that express traits which are under selection in males should also overproduce sons. However, sex allocation strategies may consist in reaction norms leading to spatiotemporal variation in the association between offspring sex ratio (SR) and parental phenotype. We analysed offspring SR in barn swallows (Hirundo rustica) over 8 years in relation to two sexually dimorphic traits: tail length and melanin-based ventral plumage coloration. The proportion of sons increased with maternal plumage darkness and paternal tail length, consistently with sexual dimorphism in these traits. The size of the effect of these parental traits on SR was large compared to other studies of offspring SR in birds. Barn swallows thus manipulate offspring SR to overproduce 'sexy sons' and potentially to mitigate the costs of intralocus sexually antagonistic selection. Interannual variation in the relationships between offspring SR and parental traits was observed which may suggest phenotypic plasticity in sex allocation and provides a proximate explanation for inconsistent results of studies of sex allocation in relation to sexual ornamentation in birds.
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Affiliation(s)
- A Romano
- Department of Biosciences, University of Milan, Milan, Italy
| | - M Romano
- Department of Biosciences, University of Milan, Milan, Italy
| | - M Caprioli
- Department of Biosciences, University of Milan, Milan, Italy
| | - A Costanzo
- Department of Biosciences, University of Milan, Milan, Italy
| | - M Parolini
- Department of Biosciences, University of Milan, Milan, Italy
| | - D Rubolini
- Department of Biosciences, University of Milan, Milan, Italy
| | - N Saino
- Department of Biosciences, University of Milan, Milan, Italy
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Merkling T, Welcker J, Hewison AM, Hatch SA, Kitaysky AS, Speakman JR, Danchin E, Blanchard P. Identifying the selective pressures underlying offspring sex-ratio adjustments: a case study in a wild seabird. Behav Ecol 2015. [DOI: 10.1093/beheco/arv032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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54
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Boulton RA, Fletcher AW. Do mothers prefer helpers or smaller litters? Birth sex ratio and litter size adjustment in cotton-top tamarins (Saguinus oedipus). Ecol Evol 2015; 5:598-606. [PMID: 25691984 PMCID: PMC4328765 DOI: 10.1002/ece3.1396] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 12/15/2014] [Indexed: 11/21/2022] Open
Abstract
Sex allocation theory has been a remarkably productive field in behavioral ecology with empirical evidence regularly supporting quantitative theoretical predictions. Across mammals in general and primates in particular, however, support for the various hypotheses has been more equivocal. Population-level sex ratio biases have often been interpreted as supportive, but evidence for small-scale facultative adjustment has rarely been found. The helper repayment (HR) also named the local resource enhancement (LRE) hypothesis predicts that, in cooperatively breeding species, mothers invest more in the sex which assists with rearing future offspring and that this bias will be more pronounced in mothers who require extra assistance (i.e., due to inexperience or a lack of available alloparents). We tested these hypotheses in captive cotton-top tamarins (Saguinus oedipus) utilizing the international studbook and birth records obtained through a questionnaire from ISIS-registered institutions. Infant sex, litter size, mother's age, parity, and group composition (presence of nonreproductive subordinate males and females) were determined from these records. The HR hypothesis was supported over the entire population, which was significantly biased toward males (the "helpful" sex). We found little support for helper repayment at the individual level, as primiparous females and those in groups without alloparents did not exhibit more extreme tendencies to produce male infants. Primiparous females were, however, more likely to produce singleton litters. Singleton births were more likely to be male, which suggests that there may be an interaction between litter size adjustment and sex allocation. This may be interpreted as supportive of the HR hypothesis, but alternative explanations at both the proximate and ultimate levels are possible. These possibilities warrant further consideration when attempting to understand the ambiguous results of primate sex ratio studies so far.
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Affiliation(s)
- Rebecca A Boulton
- Department of Biological Sciences, University of ChesterChester, U.K
- School of Biology, University of St AndrewsSt Andrews, U.K
| | - Alison W Fletcher
- Department of Biological Sciences, University of ChesterChester, U.K
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55
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Wang Y, Li Y, Wang R. The optimal sex ratio in cooperatively breeding populations. CHINESE SCIENCE BULLETIN-CHINESE 2014. [DOI: 10.1007/s11434-014-0565-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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56
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Cockburn A. Behavioral ecology as big science: 25 years of asking the same questions. Behav Ecol 2014. [DOI: 10.1093/beheco/aru177] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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57
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Sex ratio varies with egg investment in the red-necked phalarope (Phalaropus lobatus). Behav Ecol Sociobiol 2014. [DOI: 10.1007/s00265-014-1800-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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58
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Lutermann H, Cameron EZ, Raihani NJ, Bennett NC. Sex ratio variation in a eusocial mammal, the
D
amaraland mole‐rat,
F
ukomys damarensis. J Zool (1987) 2014. [DOI: 10.1111/jzo.12163] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- H. Lutermann
- Mammal Research Institute Department of Zoology and Entomology University of Pretoria Pretoria South Africa
| | - E. Z. Cameron
- Mammal Research Institute Department of Zoology and Entomology University of Pretoria Pretoria South Africa
- School of Zoology University of Tasmania Hobart Australia
| | - N. J. Raihani
- Genetics, Evolution and Environment University College London London UK
| | - N. C. Bennett
- Mammal Research Institute Department of Zoology and Entomology University of Pretoria Pretoria South Africa
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59
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Mitchell TS, Maciel JA, Janzen FJ. Does sex-ratio selection influence nest-site choice in a reptile with temperature-dependent sex determination? Proc Biol Sci 2014; 280:20132460. [PMID: 24266033 DOI: 10.1098/rspb.2013.2460] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Evolutionary theory predicts that dioecious species should produce a balanced primary sex ratio maintained by frequency-dependent selection. Organisms with environmental sex determination, however, are vulnerable to maladaptive sex ratios, because environmental conditions vary spatio-temporally. For reptiles with temperature-dependent sex determination, nest-site choice is a behavioural maternal effect that could respond to sex-ratio selection, as mothers could adjust offspring sex ratios by choosing nest sites that will have particular thermal properties. This theoretical prediction has generated decades of empirical research, yet convincing evidence that sex-ratio selection is influencing nesting behaviours remains absent. Here, we provide the first experimental evidence from nature that sex-ratio selection, rather than only viability selection, is probably an important component of nest-site choice in a reptile with temperature-dependent sex determination. We compare painted turtle (Chrysemys picta) neonates from maternally selected nest sites with those from randomly selected nest sites, observing no substantive difference in hatching success or survival, but finding a profound difference in offspring sex ratio in the direction expected based on historical records. Additionally, we leverage long-term data to reconstruct our sex ratio results had the experiment been repeated in multiple years. As predicted by theory, our results suggest that sex-ratio selection has shaped nesting behaviour in ways likely to enhance maternal fitness.
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61
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Forgotten fathers: paternal influences on mammalian sex allocation. Trends Ecol Evol 2014; 29:158-64. [DOI: 10.1016/j.tree.2013.12.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 11/25/2013] [Accepted: 12/07/2013] [Indexed: 11/24/2022]
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62
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Nichols HJ, Fullard K, Amos W. Costly sons do not lead to adaptive sex ratio adjustment in pilot whales, Globicephala melas. Anim Behav 2014. [DOI: 10.1016/j.anbehav.2013.12.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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63
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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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64
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Sardell RJ, DuVal EH. Differential allocation in a lekking bird: females lay larger eggs and are more likely to have male chicks when they mate with less related males. Proc Biol Sci 2013; 281:20132386. [PMID: 24225457 DOI: 10.1098/rspb.2013.2386] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The differential allocation hypothesis predicts increased investment in offspring when females mate with high-quality males. Few studies have tested whether investment varies with mate relatedness, despite evidence that non-additive gene action influences mate and offspring genetic quality. We tested whether female lekking lance-tailed manakins (Chiroxiphia lanceolata) adjust offspring sex and egg volume in response to mate attractiveness (annual reproductive success, ARS), heterozygosity and relatedness. Across 968 offspring, the probability of being male decreased with increasing parental relatedness but not father ARS or heterozygosity. This correlation tended to diminish with increasing lay-date. Across 162 offspring, egg volume correlated negatively with parental relatedness and varied with lay-date, but was unrelated to father ARS or heterozygosity. Offspring sex and egg size were unrelated to maternal age. Comparisons of maternal half-siblings in broods with no mortality produced similar results, indicating differential allocation rather than covariation between female quality and relatedness or sex-specific inbreeding depression in survival. As males suffer greater inbreeding depression, overproducing females after mating with related males may reduce fitness costs of inbreeding in a system with no inbreeding avoidance, while biasing the sex of outbred offspring towards males may maximize fitness via increased mating success of outbred sons.
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Affiliation(s)
- Rebecca J Sardell
- Department of Biological Science, Florida State University, , 319 Stadium Drive, Tallahassee, FL 32306-4295, USA
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65
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Riechert J, Chastel O, Becker PH. Mothers under stress? Hatching sex ratio in relation to maternal baseline corticosterone in the common tern (Sterna hirundo). J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2013; 199:799-805. [PMID: 23918311 DOI: 10.1007/s00359-013-0840-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 07/09/2013] [Accepted: 07/12/2013] [Indexed: 11/24/2022]
Abstract
Sex ratio of progeny should be balanced if costs and benefits of rearing sons and daughters are equal. However, shifts in sex ratio have been demonstrated across bird species and it was suggested that females are able to adjust the primary sex ratio. One possible mechanism is the glucocorticoid corticosterone which rises under stressful conditions and can be deposited into egg yolk by mothers. We analysed primary sex ratio of common terns Sterna hirundo from 2006 to 2008 and related it to maternal baseline corticosterone level, laying date and year. Therefore, we took 101 blood samples of 71 breeding females via blood sucking bugs, a method with negligible stress for the birds. Sex ratio did not differ from parity in any of the analysed years, which were characterized by poor food availability and breeding success. Only within 1 year there was a tendency for more females in the last hatched chick. Neither corticosterone level nor laying date or year showed an influence on hatching sex ratio. The negative result concerning primary sex ratio and maternal baseline corticosterone level might suggest conditions to be good enough for mothers to prevent them from depositing high levels of corticosterone into eggs.
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Affiliation(s)
- Juliane Riechert
- Institute of Avian Research, "Vogelwarte Helgoland", An der Vogelwarte 21, 26386 Wilhelmshaven, Germany.
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66
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Navara KJ. The role of steroid hormones in the adjustment of primary sex ratio in birds: compiling the pieces of the puzzle. Integr Comp Biol 2013; 53:923-37. [PMID: 23900275 DOI: 10.1093/icb/ict083] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
There is ample evidence that birds have the ability to adjust their offsprings' sex ratios before fertilization occurs. Recent work has focused on pinpointing when during the process of oocyte maturation adjustment of sex ratio takes place. Additionally, there is growing support for the idea that there is hormonal control over the process of adjustment of sex ratio in birds. Whether steroid hormones represent direct mediators of the process, however, remains unclear. This review outlines the precise points during maturation of ovarian follicles during which adjustment of primary sex ratios could potentially occur, compiles the evidence for hormonal involvement in the process of primary adjustment of sex ratio, and discusses potential hormonal targets during maturation and fertilization of oocytes where hormones may trigger adjustment of sex ratio in birds.
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Affiliation(s)
- Kristen J Navara
- Department of Poultry Science, The University of Georgia, Athens, GA 30602, USA
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67
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Tuero DT, Fiorini VD, Mahler B, Reboreda JC. Do sex ratio and development differ in sexually size-dimorphic shiny cowbirds ( Molothrus bonariensis) parasitizing smaller and larger hosts? Biol J Linn Soc Lond 2013. [DOI: 10.1111/bij.12130] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Diego T. Tuero
- Departamento de Ecología, Genética y Evolución; Facultad de Ciencias Exactas y Naturales; Universidad de Buenos Aires; Pabellón II Ciudad Universitaria; C1428EGS; Buenos Aires; Argentina
| | - Vanina D. Fiorini
- Departamento de Ecología, Genética y Evolución; Facultad de Ciencias Exactas y Naturales; Universidad de Buenos Aires; Pabellón II Ciudad Universitaria; C1428EGS; Buenos Aires; Argentina
| | - Bettina Mahler
- Departamento de Ecología, Genética y Evolución; Facultad de Ciencias Exactas y Naturales; Universidad de Buenos Aires; Pabellón II Ciudad Universitaria; C1428EGS; Buenos Aires; Argentina
| | - Juan C. Reboreda
- Departamento de Ecología, Genética y Evolución; Facultad de Ciencias Exactas y Naturales; Universidad de Buenos Aires; Pabellón II Ciudad Universitaria; C1428EGS; Buenos Aires; Argentina
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68
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Experience affects mating behavior, but does not impact parental reproductive allocation in a lizard. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1523-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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69
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Tagirov M, Rutkowska J. Chimeric embryos—potential mechanism of avian offspring sex manipulation. Behav Ecol 2013. [DOI: 10.1093/beheco/art007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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70
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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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71
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Jaatinen K, Öst M, Gienapp P, Merilä J. Facultative Sex Allocation and Sex-Specific Offspring Survival in Barrow's Goldeneyes. Ethology 2012. [DOI: 10.1111/eth.12048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kim Jaatinen
- ARONIA Coastal Zone Research Team; Åbo Akademi University & Novia University of Applied Sciences; Ekenäs; Finland
| | - Markus Öst
- ARONIA Coastal Zone Research Team; Åbo Akademi University & Novia University of Applied Sciences; Ekenäs; Finland
| | | | - Juha Merilä
- Ecological Genetics Research Unit, Department of Biosciences; University of Helsinki; Helsinki; Finland
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72
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Michler SPM, Nicolaus M, van der Velde M, Radersma R, Ubels R, Both C, Komdeur J, Tinbergen JM. Local offspring density and sex ratio affect sex allocation in the great tit. Behav Ecol 2012. [DOI: 10.1093/beheco/ars151] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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73
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Kristensen DL, Erikstad KE, Reiertsen TK, Moum T, Barrett RT, Jenni-Eiermann S. Are female offspring from a single-egg seabird more costly to raise? Behav Ecol 2012. [DOI: 10.1093/beheco/ars144] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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74
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75
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Pryke SR, Rollins LA. Mothers adjust offspring sex to match the quality of the rearing environment. Proc Biol Sci 2012; 279:4051-7. [PMID: 22859597 DOI: 10.1098/rspb.2012.1351] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Theory predicts that mothers should adjust offspring sex ratios when the expected fitness gains or rearing costs differ between sons and daughters. Recent empirical work has linked biased offspring sex ratios to environmental quality via changes in relative maternal condition. It is unclear, however, whether females can manipulate offspring sex ratios in response to environmental quality alone (i.e. independent of maternal condition). We used a balanced within-female experimental design (i.e. females bred on both low- and high-quality diets) to show that female parrot finches (Erythrura trichroa) manipulate primary offspring sex ratios to the quality of the rearing environment, and not to their own body condition and health. Individual females produced an unbiased sex ratio on high-quality diets, but over-produced sons in poor dietary conditions, even though they maintained similar condition between diet treatments. Despite the lack of sexual size dimorphism, such sex ratio adjustment is in line with predictions from sex allocation theory because nutritionally stressed foster sons were healthier, grew faster and were more likely to survive than daughters. These findings suggest that mothers may adaptively adjust offspring sex ratios to optimally match their offspring to the expected quality of the rearing environment.
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Affiliation(s)
- Sarah R Pryke
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.
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76
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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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77
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Leshyk R, Nol E, Burke DM, Burness G. Logging affects fledgling sex ratios and baseline corticosterone in a forest songbird. PLoS One 2012; 7:e33124. [PMID: 22432000 PMCID: PMC3303809 DOI: 10.1371/journal.pone.0033124] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 02/06/2012] [Indexed: 11/30/2022] Open
Abstract
Silviculture (logging) creates a disturbance to forested environments. The degree to which forests are modified depends on the logging prescription and forest stand characteristics. In this study we compared the effects of two methods of group-selection (“moderate” and “heavy”) silviculture (GSS) and undisturbed reference stands on stress and offspring sex ratios of a forest interior species, the Ovenbird (Seiurus aurocapilla), in Algonquin Provincial Park, Canada. Blood samples were taken from nestlings for corticosterone and molecular sexing. We found that logging creates a disturbance that is stressful for nestling Ovenbirds, as illustrated by elevated baseline corticosterone in cut sites. Ovenbirds nesting in undisturbed reference forest produce fewer male offspring per brood (proportion male = 30%) while logging with progressively greater forest disturbance, shifted the offspring sex ratio towards males (proportion male: moderate = 50%, heavy = 70%). If Ovenbirds in undisturbed forests usually produce female-biased broods, then the production of males as a result of logging may disrupt population viability. We recommend a broad examination of nestling sex ratios in response to anthropogenic disturbance to determine the generality of our findings.
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Affiliation(s)
- Rhiannon Leshyk
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, Ontario, Canada.
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78
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Rypel AL, Pounds KM, Findlay RH. Spatial and Temporal Trade-Offs by Bluegills in Floodplain River Ecosystems. Ecosystems 2012. [DOI: 10.1007/s10021-012-9528-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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79
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Katsuki M, Harano T, Miyatake T, Okada K, Hosken DJ. Intralocus sexual conflict and offspring sex ratio. Ecol Lett 2012; 15:193-7. [PMID: 22225600 DOI: 10.1111/j.1461-0248.2011.01725.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Males and females frequently have different fitness optima for shared traits, and as a result, genotypes that are high fitness as males are low fitness as females, and vice versa. When this occurs, biasing of offspring sex-ratio to reduce the production of the lower-fitness sex would be advantageous, so that for example, broods produced by high-fitness females should contain fewer sons. We tested for offspring sex-ratio biasing consistent with these predictions in broad-horned flour beetles. We found that in both wild-type beetles and populations subject to artificial selection for high- and low-fitness males, offspring sex ratios were biased in the predicted direction: low-fitness females produced an excess of sons, whereas high-fitness females produced an excess of daughters. Thus, these beetles are able to adaptively bias sex ratio and recoup indirect fitness benefits of mate choice.
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Affiliation(s)
- Masako Katsuki
- Graduate School of Environmental Science, Okayama University, Tsushima-naka 1-1-1, Okayama, Japan
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80
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Tang XL, Yue F, Zhang DJ, Yan XF, Xin Y, Wang C, Chen Q. The effect of operational sex ratio on sex allocation and neonate phenotype in a viviparous lizard Eremias multiocellata. AMPHIBIA-REPTILIA 2012. [DOI: 10.1163/15685381-00002851] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Maternal investment in the production of male versus female neonates was approximately equal in most animal species. However, sex allocation theory predicts that under certain conditions, selection may favor the females’ ability to adjust the sex ratio of their offspring, which females tend to use more for an investment of the rare sex. The mechanism of operational sex ratio (OSR) influence on sex allocation is still unclear, and recent studies conducted on lizards have reached conflicting conclusions. Here, we selected a viviparous lizard Eremias multiocellata to test whether pregnant females could adjust the sex ratio of their offspring in response to OSRs. Our results showed that mothers did not adjust the sex ratios or phenotypes of neonates in the laboratory and field-based experiments, except tail length. However, the OSRs subsequently affected growth in both mass and SVL of the offspring in laboratory experiments; whereas only the mass was affected in the semi-nature field experiments. Our results, thus, contradict the predictions of sex allocation theory and challenge the idea that female investment in the scarcity sex might serve as a mechanism which is used for adjusting the population sex ratio.
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Affiliation(s)
- Xiao-Long Tang
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, Gansu, P. R. China
| | - Feng Yue
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, Gansu, P. R. China
| | - De-Jiu Zhang
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, Gansu, P. R. China
| | - Xue-Feng Yan
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, Gansu, P. R. China
| | - Ying Xin
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, Gansu, P. R. China
| | - Cui Wang
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, Gansu, P. R. China
| | - Qiang Chen
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, Gansu, P. R. China
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81
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Influence of translocation strategy and mating system on the genetic structure of a newly established population of island ptarmigan. CONSERV GENET 2011. [DOI: 10.1007/s10592-011-0300-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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82
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Romano A, Ambrosini R, Caprioli M, Bonisoli-Alquati A, Saino N. Secondary sex ratio covaries with demographic trends and ecological conditions in the barn swallow. Evol Ecol 2011. [DOI: 10.1007/s10682-011-9543-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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83
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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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84
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Dolenec P, Kocijan I, Dolenec Z. Intra-seasonal changes in reproductive strategy of a multi-brooded passerine: the tree sparrowPasser montanus. ETHOL ECOL EVOL 2011. [DOI: 10.1080/03949370.2011.585181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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85
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Bowers EK, Sakaluk SK, Thompson CF. Adaptive sex allocation in relation to hatching synchrony and offspring quality in house wrens. Am Nat 2011; 177:617-29. [PMID: 21508608 DOI: 10.1086/659630] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Increased variance in the reproductive success of males relative to females favors mothers that optimally allocate sons and daughters to maximize their fitness return. In altricial songbirds, one influence on the fitness prospects of offspring arises through the order in which nestlings hatch from their eggs, which affects individual mass and size before nest leaving. In house wrens (Troglodytes aedon), the influence of hatching order depends on the degree of hatching synchrony, with greater variation in nestling mass and size within broods hatching asynchronously than in those hatching synchronously. Early-hatching nestlings in asynchronous broods were heavier and larger than their later-hatching siblings and nestlings in synchronous broods. The effect of hatching order was also sex specific, as the mass of males in asynchronous broods was more strongly influenced by hatching order than the mass of females, with increased variation in the mass of males relative to that of females. As predicted, mothers hatching their eggs asynchronously biased first-laid, first-hatching eggs toward sons and late-laid, late-hatching eggs toward daughters, whereas females hatching their eggs synchronously distributed the sexes randomly among the eggs of their clutch. We conclude that females allocate the sex of their offspring among the eggs of their clutch in a manner that maximizes their own fitness.
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Affiliation(s)
- E Keith Bowers
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, 61790, USA.
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86
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Pryke SR, Rollins LA, Griffith SC. CONTEXT-DEPENDENT SEX ALLOCATION: CONSTRAINTS ON THE EXPRESSION AND EVOLUTION OF MATERNAL EFFECTS. Evolution 2011; 65:2792-9. [DOI: 10.1111/j.1558-5646.2011.01391.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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87
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Pryke SR, Rollins LA, Buttemer WA, Griffith SC. Maternal stress to partner quality is linked to adaptive offspring sex ratio adjustment. Behav Ecol 2011. [DOI: 10.1093/beheco/arr040] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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88
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Postma E, Heinrich F, Koller U, Sardell RJ, Reid JM, Arcese P, Keller LF. Disentangling the effect of genes, the environment and chance on sex ratio variation in a wild bird population. Proc Biol Sci 2011; 278:2996-3002. [PMID: 21345862 DOI: 10.1098/rspb.2010.2763] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sex ratio theory proposes that the equal sex ratio typically observed in birds and mammals is the result of natural selection. However, in species with chromosomal sex determination, the same 1 : 1 sex ratio is expected under random Mendelian segregation. Here, we present an analysis of 14 years of sex ratio data for a population of song sparrows (Melospiza melodia) on Mandarte Island, at the nestling stage and at independence from parental care. We test for the presence of variance in sex ratio over and above the binomial variance expected under Mendelian segregation, and thereby quantify the potential for selection to shape sex ratio. Furthermore, if sex ratio variation is to be shaped by selection, we expect some of this extra-binomial variation to have a genetic basis. Despite ample statistical power, we find no evidence for the existence of either genetic or environmentally induced variation in sex ratio, in the nest or at independence. Instead, the sex ratio variation observed matches that expected under random Mendelian segregation. Using one of the best datasets of its kind, we conclude that female song sparrows do not, and perhaps cannot, adjust the sex of their offspring. We discuss the implications of this finding and make suggestions for future research.
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Affiliation(s)
- Erik Postma
- Institute of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
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89
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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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90
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Covas R, Deville AS, Doutrelant C, Spottiswoode CN, Grégoire A. The effect of helpers on the postfledging period in a cooperatively breeding bird, the sociable weaver. Anim Behav 2011. [DOI: 10.1016/j.anbehav.2010.09.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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91
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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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92
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Affiliation(s)
- Henry F Howe
- Biological Sciences (m/c 066), University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607, USA.
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93
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Blackburn GS, Albert AYK, Otto SP. The evolution of sex ratio adjustment in the presence of sexually antagonistic selection. Am Nat 2010; 176:264-75. [PMID: 20653443 DOI: 10.1086/655220] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Sex ratio adjustment (SRA) of broods has received widespread interest as a means for optimizing parental investment in offspring. Classical explanations for the evolution of SRA focus on improving offspring fitness in light of resource availability or mate attractiveness. Here, we use genetic models to demonstrate that SRA can evolve to alleviate sexual antagonism by improving the chance that the alleles of a sexually antagonistic trait are transmitted to the sex they benefit. In cases where the trait is autosomally inherited, this result is obtained regardless of whether SRA is based on the mother's or the father's genotype and irrespective of the recombination rate between the trait and SRA loci. SRA also evolves in this manner when the trait is sex-linked, provided that SRA decisions are based on the homogametic genotype (XX mothers or ZZ fathers). By contrast, when based on traits in the heterogametic sex, SRA promotes fixation of the allele that is detrimental to that sex, preventing the evolution of substantial levels of SRA. Our models indicate that the evolution of SRA in nature should be strongly influenced by the genetic architecture of the traits on which it is based and the form of selection affecting them.
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Affiliation(s)
- Gwylim S Blackburn
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, Canada
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94
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ROBERT KA, SCHWANZ LE. Emerging sex allocation research in mammals: marsupials and the pouch advantage. Mamm Rev 2010. [DOI: 10.1111/j.1365-2907.2010.00168.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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95
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Individuals and populations: the role of long-term, individual-based studies of animals in ecology and evolutionary biology. Trends Ecol Evol 2010; 25:562-73. [PMID: 20828863 DOI: 10.1016/j.tree.2010.08.002] [Citation(s) in RCA: 514] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 08/01/2010] [Accepted: 08/02/2010] [Indexed: 11/23/2022]
Abstract
Many important questions in ecology and evolutionary biology can only be answered with data that extend over several decades and answering a substantial proportion of questions requires records of the life histories of recognisable individuals. We identify six advantages that long-term, individual based studies afford in ecology and evolution: (i) analysis of age structure; (ii) linkage between life history stages; (iii) quantification of social structure; (iv) derivation of lifetime fitness measures; (v) replication of estimates of selection; (vi) linkage between generations, and we review their impact on studies in six key areas of evolution and ecology. Our review emphasises the unusual opportunities and productivity of long-term, individual-based studies and documents the important role that they play in research on ecology and evolutionary biology as well as the difficulties they face.
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96
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Sex allocation in Savi’s warblers Locustella luscinioides: multiple factors affect seasonal trends in brood sex ratios. Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-1046-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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97
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Drobniak SM, Wiejaczka D, Arct A, Dubiec A, Gustafsson L, Cichoń M. Sex-specific heritability of cell-mediated immune response in the blue tit nestlings (Cyanistes caeruleus). J Evol Biol 2010; 23:1286-92. [PMID: 20456564 DOI: 10.1111/j.1420-9101.2010.01993.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Here, we aimed at estimating sex-specific heritabilities of cell-mediated immune response (CMI) in the blue tit nestlings (Cyanistes caeruleus). To separate genetic and environmental components of the phenotypic variance in CMI (measured using phytohaemagglutinin assay), we performed a cross-fostering experiment. Additionally, controlled environmental variation was introduced by enlarging some broods. Our analyses revealed a significant genetic component (as approximated by the nest-of-origin term) of the phenotypic variance in immune response. More importantly, these genetic effects differed between sexes and experimentally manipulated brood sizes, as indicated by significant genotype-by-sex and genotype-by-environment interactions. We discuss possible causes of such sexual dimorphism in gene expression and suggest that sex- and environment-specific genetic interactions may contribute to the maintenance of genetic variability in traits related to immune functions.
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Affiliation(s)
- Szymon M Drobniak
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland.
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98
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Zhang DJ, Tang XL, Yue F, Chen Z, Li RD, Chen Q. Effect of gestation temperature on sexual and morphological phenotypes of offspring in a viviparous lizard, Eremias multiocellata. J Therm Biol 2010. [DOI: 10.1016/j.jtherbio.2010.01.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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99
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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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100
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STELKENS RIKEB, WEDEKIND CLAUS. Environmental sex reversal, Trojan sex genes, and sex ratio adjustment: conditions and population consequences. Mol Ecol 2010; 19:627-46. [DOI: 10.1111/j.1365-294x.2010.04526.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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