Evolutionary theories of ageing and senescence provide a framework that allows to understand why apparently maladaptive senescent phenotypes are observed under natural conditions, despite the fact that natural selection should, at first sight, be opposed to mechanisms that lead to the deterioration of bodily functions with advancing age. While ageing has been shown in the wild and has been explored under artificial laboratory conditions, sex-dependent pattern were not considered in detail. The aim of this thesis is to draw from the existing theories of sexual selection, life-history and sexual conflict, to get a more complete understanding of sex-specific effects on ageing patterns. The organism I use in all experiments is the Black Field Cricket Teleogryllus commodus. To test for sex-specific demographic ageing patterns in the wild, I use a capture-mark-recapture study and analyse the resulting data with a new method that combines classic capture-recapture models with a recent mathematical technique that allows to estimate survival probabilities from recapture data for which the date of births of animals are unknown (Chapter 2). I test for reproductive and demographic ageing under near-natural conditions in field enclosure (Chapter 3). In laboratory based manipulation studies I estimate the effect of a) different juvenile and adult diets on the ageing patterns (Chapter 4), and b) a reduction of the ability to spend energy on calling and how this relates to lifespan (Chapter 5). In a half-sib breeding design I measure early and late reproductive effort in males and in females to estimate genetic correlations and thereby test for antagonistic pleiotropy between early and late components and between males and females. The studies in the wild indicate that Teleogryllus commodus senesce under natural conditions and that males have overall higher mortality rates. Females, not males, show reproductive ageing under both enclosure and laboratory conditions. The genetic architecture revealed no discord between male and female fitness components and there was no evidence for antagonistic pleiotropy between early and late fitness components. These results show that a) it is important to include male measures of reproductive effort in ageing studies and that b) the field of ageing research should benefit a lot from incorporating sexual selection, life-history and sexual conflict theory.
| Identifer | oai:union.ndltd.org:ADTP/242698 |
| Date | January 2007 |
| Creators | Zajitschek, Felix , Biological, Earth and Environmental Sciences, Faculty of Science, UNSW |
| Publisher | Awarded by:University of New South Wales. |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Felix Zajitschek, http://unsworks.unsw.edu.au/copyright |
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