Eco-evolutionary mechanisms shaping aggregation and ‘piggy-backing’ of the endemic Kermadec Islands giant limpet, Scutellastra kermadecensis : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biological Sciences at Massey University, Albany, New Zealand
| dc.contributor.author | Kim, Julia (Ji Hyun) | |
| dc.date.accessioned | 2023-03-23T20:29:40Z | |
| dc.date.available | 2023-03-23T20:29:40Z | |
| dc.date.issued | 2022 | |
| dc.description.abstract | The Kermadec giant limpet, Scutellastra kermadecensis, is a broadcast-spawning, protandrous hermaphrodite that is endemic to Rangitāhua, Kermadec archipelago, New Zealand. This limpet is the most abundant intertidal/shallow-subtidal grazer on these islands and lives at very high density, covering most of the available rocky substrate. Nonetheless, the species is extremely range-restricted and therefore vulnerable to extinction. My thesis investigated the socioecology of the Kermadec giant limpet, using surveys as well as genetic analysis of relatedness and spatial structure to better understand the population dynamics of this species. In Chapter 2, I focused on the “piggy-backing” habit of these limpets, whereby small limpets (piggies), predominantly male, piggy-back on the shells of larger, predominantly female, limpets. I investigated whether the ontogenetic habitat shift between piggy-backing and being rock-attached was determined by rock space availability, as a mechanism to avoid bulldozing by larger limpets, to access grazing opportunities on limpet shells, and/or to monopolize breeding with rock-attached females. I found that available rock space did not influence the transitional size from being a piggy to rock-attached, suggesting that social environment motivated piggy-backing behaviour rather than space constraints. As spatial proximity often determines fertilization success in broadcast spawning marine invertebrates, in Chapter 3, I investigated the genetic relationships of piggy-host pairs, and among neighbouring limpets. I sought to understand whether the species had mechanisms to promote genetic diversity, such as kin-avoidance in piggy-host pairings, or among piggies on the same host, or whether there was evidence for limpets moving away from relatives when transitioning from piggy-backing to being rock-attached. I found that paired and neighbouring limpets were no more related to each other than to any other sampled limpet in the subpopulation. However, there was spatial genetic structure among sampled sites and locations, and evidence for adaptive genetic divergence over very small scales (<1 metre). Furthermore, estimated levels of inbreeding were very high (FIS = 1.37-1.43), but in keeping with estimates for other marine invertebrates. Unveiling these eco-evolutionary drivers of piggy-backing behaviour helps us to understand how Kermadec giant limpets have persisted despite their isolation and provides insight into how to conserve them. | en |
| dc.identifier.uri | http://hdl.handle.net/10179/18107 | |
| dc.language.iso | en | en |
| dc.publisher | Massey University | en |
| dc.rights | The Author | en |
| dc.subject.anzsrc | 310307 Population ecology | en |
| dc.subject.anzsrc | 310907 Animal physiological ecology | en |
| dc.title | Eco-evolutionary mechanisms shaping aggregation and ‘piggy-backing’ of the endemic Kermadec Islands giant limpet, Scutellastra kermadecensis : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biological Sciences at Massey University, Albany, New Zealand | en |
| dc.type | Thesis | en |
| massey.contributor.author | Kim, Julia (Ji Hyun) | |
| thesis.degree.discipline | Biological Sciences | en |
| thesis.degree.level | Masters | en |
| thesis.degree.name | Master of Science (MSc) | en |