Adaptive sex ratio manipulation in the common moorhen (Gallinula chloropus) / Debbie F. Mauney.
| Author/creator | Mauney, Debbie F. author. |
| Other author | McRae, Susan B. (Susan Barbara), 1967- degree supervisor. |
| Other author | East Carolina University. Department of Biology. |
| Format | Theses and dissertations |
| Production | 2009. |
| Description | 84 leaves : illustrations (some color) ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | In many avian species, skews in offspring sex ratios within and between clutches have been observed in relation to paternal attractiveness, maternal condition, laying order, hatch order and breeding attempt within a season. I examined patterns in sex ratio bias in the common moorhen {Gall̕nula chloropus) to determine whether offspring sex ratios are influenced by paternal attractiveness, breeding attempt within a season, and laying sequence within a clutch. I predicted that females in good condition mated to attractive, high quality males would produce male-biased brood sex ratios. Using generalized linear models, I found that while overall brood sex ratios were slightly female-biased, the first 3 eggs in a brood and the 1st half of broods were significantly male-biased, especially in early breeding attempts in the season. Male-bias in early eggs was correlated with parental condition, particularly paternal sexual traits. Offspring survival was significantly influenced by hatch month: chicks hatched early in the breeding season achieved significantly higher survival to the following Spring over later- laid chicks. Female moorhens in good condition produced more sons early in the breeding season and early within clutches in response to their mate's phenotype. This strategy may be adaptive since I found a survival advantage to being hatched early in the season. These early broods also hatched more synchronously. Males predominated in early eggs, so this may have reduced competitive asymmetries within broods, thereby providing early sons with an extra survival advantage. In spite of conventional sexual size dimorphism favoring males, moorhens show unusual sex-role reversal, with females competing for males. This paradox in behavior among females suggests that in a population where there are plenty of males to choose from, females may compete for males of high quality. Early-laid chicks will have a substantial growth and competitive advantage over later-laid chicks within a breeding season and are more likely to be recruited at the beginning of the next breeding season. Early recruitment and the possibility of polygynous mating may result in higher fitness through male offspring than through females. Thus, females may gain fitness benefits by producing sons early due to increased survival of these early sons combined with increased chances of their early recruitment and enhanced lifetime reproductive success. |
| General note | Presented to the faculty of the Department of Biology. |
| General note | Advisor: Susan B. McRae |
| Dissertation note | M.S. East Carolina University 2009 |
| Bibliography note | Includes bibliographical references (leaves 78-84). |
| Genre/form | dissertations. |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
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