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Avian sex ratios—considerations and applications for the conservation management of birds1.42 MB
Thesis Embargoed Access, Embargo ends: 05-Dec-2024
Dissertation
Avian sex ratios—considerations and applications for the conservation management of birds
University of the Sunshine Coast, Queensland
Doctor of Philosophy, University of the Sunshine Coast, Queensland
2023
DOI:
https://doi.org/10.25907/00797
Abstract
With one in eight bird species now threatened with extinction and many others in decline, there has never been a greater need to understand avian reproductive biology and expand management options. Despite a vast array of conservation efforts worldwide, many bird species will require an ongoing integrated management approach, that is, combining in-situ and ex-situ strategies to achieve species conservation goals and ultimately ecosystem functionality.
As populations decline in size, the combined effects of factors such as environmental stochasticity, inbreeding depression, and allee effects are exacerbated. Advancements in our knowledge of the fluidity of avian sex determination processes have revealed additional contributors to the extinction vortex. Female birds (carrying both Z and W sex chromosomes) may skew the primary or secondary sex of their offspring in response to physiological stressors in the maternal environment. Endocrine disrupting chemicals and the stress hormone corticosterone for example, are known to disrupt normal reproductive pathways and redirect the primary or secondary sex of their offspring. Sex reversed birds are most commonly genetic females with testes; however, genetic males may also feminise. Such individuals are often reproductively redundant, potentially produce only male (ZZ) offspring and exacerbate the demise of small or otherwise threatened populations.
Here, I compared the genetic sex with the morphological characteristics of deceased wild birds to identify the incidence of sex reversals in five common species from four avian orders. This first of its kind study suggests that sex reversals occur at higher-thanexpected rates in free-living avian populations and the occurrence is expected to be widespread amongst the orders. In subsequent research chapters I examine sex ratio differences in global captive populations at various levels of governance, threat status and between and within orders and develop a novel technique to expand the practice of in-ovo sexing of embryos to species producing thick or opaque eggs, thus allowing the preferential hatching of threatened species such as cassowary (Casuarius spp.), crane species (Grus spp.) and isolated populations of emu (Dromaius novaehollandiae).
Details
- Title
- Avian sex ratios—considerations and applications for the conservation management of birds
- Authors
- Clancy Hall - University of the Sunshine Coast, Queensland, School of Science, Technology and Engineering
- Contributors
- Dominique Potvin (Supervisor) - University of the Sunshine Coast, Queensland, School of Science, Technology and EngineeringGabriel Conroy (Supervisor) - University of the Sunshine Coast, Queensland, Centre for Bioinnovation
- Awarding institution
- University of the Sunshine Coast, Queensland
- Degree awarded
- Doctor of Philosophy
- Publisher
- University of the Sunshine Coast, Queensland
- DOI
- 10.25907/00797
- Organisation Unit
- Academic Support Unit; School of Science, Technology and Engineering; Centre for Bioinnovation; University of the Sunshine Coast, Queensland
- Language
- English
- Record Identifier
- 99981497802621
- Output Type
- Dissertation
Metrics
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