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dc.contributor.advisorPainting, Chrissie
dc.contributor.authorLambert, Michaela
dc.date.accessioned2022-05-24T02:51:33Z
dc.date.available2022-05-24T02:51:33Z
dc.date.issued2021
dc.identifier.urihttps://hdl.handle.net/10289/14874
dc.description.abstractSexual selection is thought to be the main driver for the evolution of pre-copulatory traits (e.g., weapons and ornaments) used to gain access to mates, and post-copulatory traits (e.g., sperm form and function) used to maximize fertilisation success. Individuals that have a greater ability to acquire resources from their environment may be able to invest in both types of traits equally, and therefore may have a competitive advantage during mate acquisition and sperm competition. For males that are competitively inferior, they may choose to invest more into one type of trait, resulting in a trade-off between the investment in one trait over another. The New Zealand giraffe weevil, Lasiorhynchus barbicornis, provides an ideal study system to explore size-dependent investment in sexual traits. Males show extreme size variability, leading to differences in mating success between males of different body sizes. Large males are better at acquiring mates and winning fights and as a result, small males have adopted a sneaking tactic to avoid pre-copulatory competition with larger rivals. Therefore, small males may choose to invest more into their post-copulatory traits. Further, giraffe weevils form large aggregations on host trees during the summer months, making them an ideal subject to explore how demographic factors can influence the mating success of males. In giraffe weevils, how body size and population density interact to influence mating success is not well understood. In this study, I used an experimental behavioural assay and morphometrics to investigate how males of different body sizes may be investing into their pre- and post-copulatory traits to engage or avoid sperm competition. I found that small males may be investing more into post-copulatory traits than large males. However, I found no evidence of a phenotypic trade-off between pre- and post-copulatory traits. I also used an observational dataset collected from a natural population to explore how population density, among other demographic factors, interact with body size to influence male mating success. I found that male giraffe weevils have density-dependent mating success, with small males doing best at high densities, and large males at low densities. My research will contribute to a growing body of work looking at how sexual selection can shape the life-history traits of insects.
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherThe University of Waikato
dc.rightsAll items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectEcology
dc.subjectSperm competition
dc.subjectBehavioural ecology
dc.subject.lcshBeetles -- Sexual behavior -- New Zealand
dc.subject.lcshInsects -- New Zealand -- Reproduction
dc.subject.lcshBeetles -- New Zealand -- Geographical distribution
dc.subject.lcshSexual behavior in animals -- New Zealand
dc.subject.lcshSperm competition -- New Zealand
dc.titleThe effect of population density on mating dynamics and the interaction between pre- and post-copulatory selection in the New Zealand giraffe weevil
dc.typeThesis
thesis.degree.grantorThe University of Waikato
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (Research) (MSc(Research))
dc.date.updated2022-05-11T22:35:37Z
pubs.place-of-publicationHamilton, New Zealanden_NZ


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