Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 186 for “"sex ratio"”.
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Encoding sex ratio information: automatic or effortful?
Operational Sex Ratio (OSR: the ratio of reproductively viable males to females in a given population) has been theorized and studied as a construct that may influence behaviors. The encoding of sex ratio was examined in order to determine whether the cognitive process underlying it is automatic or …
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Dioecious Plants: Evolution And Sex Ratio And Asepen Decline
… dioecious species are rare in nature, the sexual system appears in a diverse number of families and across all life forms and global locations. We looked at the population dynamics of natural populations to determine why many dioecious populations display biased sex ratios. We also looked …
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Causes and consequences of sex ratio bias in Nazca boobies
… reproductive and demographic studies. The adult sex ratio at this colony has been significantly male biased for more than twenty years. Knowledge of the ontogeny of this bias provides critical context that allows proper framing of hypotheses regarding parental sex allocation, the relative …
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Examining skewed sex ratio in the mountain plover (Charadrius montanus) population
Skewed sex ratios can have negative implications for population growth or persistence if not congruous for a species system. A skewed tertiary sex ratio (2.3 males per female) has been detected in the breeding population of a grassland shorebird experiencing population declines, the mountain plover …
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Examining skewed sex ratio in the mountain plover (Charadrius montanus) population
Skewed sex ratios can have negative implications for population growth or persistence if not congruous for a species system. A skewed tertiary sex ratio (2.3 males per female) has been detected in the breeding population of a grassland shorebird experiencing population declines, the mountain plover …
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Eastern Pipistrelle (Perimyotis subflavus) Internal Temperature Differences and Sex Ratio in Gorman Cave Hibernaculum
… variables on the internal temperature and sex ratio were assessed. Bats in hibernation are known for leaving and returning to stages of torpor. Gender had no apparent effect on the internal temperature of eastern pipistrelles and any variation in internal temperature was more of a …
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Effect of nestling sex ratio on the provisioning behavior of adult Eastern Bluebirds (Sialia sialis)
… invest in sons and daughters, i.e., sex-biased parental investment. Preferential provisioning behavior has been reported in one population of Eastern Bluebirds (<em>Sialia sialis</italic>) and attributed to local resource competition. To better understand this behavior, I studied the …
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Seasonal and Ontogenetic Changes in the Sex Ratio of a Population of Stinkpots (Kinosternidae: Sternotherus odoratus)
… suggest turtle populations with biased sex ratios are the result of sampling errors such as improper sex determination, trapping bias, and behavioral differences between the sexes. This study was undertaken to determine if the observed sex ratio of a population of stinkpots (Sternotherus …
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The relationship of sexual dimorphism and differential predation to sex ratio in Leptochelia dubia (Crustacea: Tanaidacea)
… which broods its young and exhibits marked sexual dimorphism. The species is widely distributed in the Pacific, Atlantic, Mediterranean and Indian Oceans, but to date there are no published accounts of its ecology. L. dubia is one of the most abundant of the small Crustacea in Tomales Bay, …
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Sexual selections in the northern fall field cricket, Gryllus pennsylvanicus: a manipulation of the adult sex ratio
The operational sex ratio has long been considered an important constraint on the structure of mating systems. The effects of an experimentally manipulated sex ratio on mating behavior and selection were investigated in a polygynous species, Gryllus pennsylvanicus, where the potential exists for …
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Drivers of a Temporal Change in the Adult Sex Ratio of a Population of Roosevelt elk (Cervus elaphus roosevelti)
Ecological processes driving female-biased adult sex ratios (ASR, males:female) in ungulate populations have been addressed theoretically but empirical study is lacking. The female-substitution hypothesis asserts that a female-biased ASR reflects an overall fitness benefit to females and also males …
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The influence of initial length of uterus per embryo and gestation stage on prenatal survival, development and sex ratio in the pig
… gestation on embryonic survival, development and sex ratio were determined by systematically restricting embryos to 5, 10, 15, 20, 25, 30, 35, 40, 45 or more than 50 cm of initial uterine length per potential embryo and examining the reproductive tracts at d 17, 23, 29, 35 or 41 of gestation. At d …
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A dynamic white-tailed deer population simulator and lessons from its use
… virginianus). It is based on a dynamic age and sex-specific algorithm, unifying bioenergetic, sociological, hunter, and population characteristics. The system determines a management plan that will stabilize a population under the conditions specified. The system is also designed to be used for …
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The Economics of Marriage and Divorce in Iran
… the change in age structure that influences the sex ratio. I consider the influence of the sex ratio on couples' age and education gaps using data from multiple national surveys from 1984-2007. The findings of this chapter show that a lower sex ratio, i.e. a greater supply of marriage-age women, …
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Traditional Agricultural Practices and Sex Ratios at Birth in Modern Times
… traditional agricultural practices on observed sex ratios at birth over last four decades. Building on the plough hypothesis developed by Ester Boserup and the work of Alesina et al. (2013), this study provides a further empirical test of the legacy of the plough. I perform empirical analysis on …
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Variation du sex-ration chez les jeunes kangourous gris de l'est (Macropus giganteus) en fonction de caractéristiques maternelles
Pour une étude de population un sex-ratio à la naissance déviant de la parité peut avoir un impact important dans un contexte de conservation. En effet, un plus grand nombre d’individus d’un sexe peu affecter les dynamiques de population chez une espèce donnée. Plus d’une dizaine d’hypothèses …
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Essays on Fertility and Sex Ratios in India
… have experienced a rapid increase in their sex ratios at birth. This dissertation examines the causes and consequences of these imbalances in the Indian context. Lower desired fertility can translate into more male-biased sex ratios if son preference remains strong, especially with greater …
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