Dissertation
Reproductive strategies of females in the red-backed fairy wren (Malurus melanocephalus)
Washington State University
Doctor of Philosophy (PhD), Washington State University
12/2008
DOI:
https://doi.org/10.7273/000005577
Abstract
When females are limited in the quantity of offspring they can produce, one way they can improve their reproductive success is by increasing offspring quality. Here we examine two ways in which females red-backed fairy-wrens may produce higher quality offspring, first through sex ratio manipulation, and second through choice of extra-pair mates. If one sex of offspring has a greater chance of surviving and reproducing then females benefit if they preferentially produce that sex. Depending on the benefit provided by auxiliary helpers, females in cooperatively breeding species may either prefer to produce the helping sex, in order to gain their assistance with future reproduction, or the dispersing sex, in order to avoid local competition between relatives. In the red-backed fairy-wren we found that females gain little or no fitness benefit from auxiliary males and accordingly females with auxiliaries tend to produce broods biased towards the dispersing sex. Further, the population wide primary sex ratio is biased towards the dispersing sex. Extra-pair mating is another way that females may increase the quality of their offspring. However, because the benefits of extra-pair mating are indirect, if large direct costs are associated with this behavior, it cannot evolve as an adaptive female strategy. In the red-backed fairy-wren we found little or no cost associated with extra-pair mating. This suggests that indirect benefits to females may partially drive the evolution of extra-pair mating. One benefit that females may gain is through extra-pair mating is increased offspring heterozygosity. This may be particularly important when dispersal is limited and inbreeding is common. We found that female red-backed fairy-wrens who produce extra-pair offspring are more related to their social mates than those who do not and that extra-pair offspring are more heterozygous than within-pair offspring. Further, an experimental test shows that females paired to closely related males produce a greater proportion of extra-pair young than those paired to unrelated males. Thus there appear to be several behaviors female red-backed fairy-wrens use to increase offspring quality.
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Details
- Title
- Reproductive strategies of females in the red-backed fairy wren (Malurus melanocephalus)
- Creators
- Claire Willow Varian Ramos
- Contributors
- Michael S. Webster (Chair)Hubertus Georg Schwabl (Committee Member) - Washington State University, School of Biological SciencesPaul Adam Verrell (Committee Member) - Washington State University, School of Biological SciencesRichard Gomulkiewicz (General Contributor) - Washington State University, School of Biological Sciences
- Awarding Institution
- Washington State University
- Academic Unit
- School of Biological Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 132
- Identifiers
- 99901054739901842
- Language
- English
- Resource Type
- Dissertation