Show simple item record

dc.contributor.advisorIngram, Travis
dc.contributor.authorMorrison, Scott
dc.date.available2016-10-09T20:36:59Z
dc.date.copyright2016
dc.identifier.citationMorrison, S. (2016). Life history variation and diet preference in non-diadromous Otago galaxiids (Thesis, Master of Science). University of Otago. Retrieved from http://hdl.handle.net/10523/6824en
dc.identifier.urihttp://hdl.handle.net/10523/6824
dc.description.abstractLife history theory states that selection acts upon individuals to produce optimal reproductive success, through maximising number of recruited offspring. Selection pressures vary across different environments and subsequently produce a wide variation in optimal life history, resulting in variation of life history traits. Previous research has identified that life history variation can occur across large scale latitudinal and elevational gradients and between small scale allopatric populations. Research concerning the diets and life history variation at early life stages, particularly in fish, is severely limited. This thesis investigates the importance of diets and resource availability on the observed life history variation between four species of the ‘Galaxias vulgaris complex’; G. anomalus, G. eldoni, G. depressiceps and G. pullus across an altitude gradient and between life history categories at the larval life stage. Diet analyses displayed that Chironomidae were the most prevalent food item, which accounted for 62% of the observed diet contents, followed by Copepoda (20%) and Algae (8%). Chironomidae commonly dominate small freshwater fish diets, and as predicted, larval galaxiid populations displayed a correlation between larval galaxiid length and prey item size, as expected in gape-size limited fish. Additionally, species was observed to be a much poorer predictor of prey item length than either larval length or site. Galaxiids also displayed higher selectivity when exposed to extreme resource abundance. However, there were no significant trends observed between galaxiid diets and elevation or life history categories. Conversely, invertebrate communities displayed significantly greater diversity at fast life history populations than intermediate life history populations. Additionally, diets consistently displayed significantly lower diversity than their respective invertebrate community. This research highlights the importance of investigating multiple selection pressures when attempting to discern causal effects of life history variation. It is likely that, while resource abundance is important in defining life history, other selection pressures, such as disturbance and predation may be acting as stronger selection pressures upon populations of larval galaxiids.
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherUniversity of Otago
dc.rightsAll items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectGalaxias
dc.subjectOtago
dc.subjectdepressiceps
dc.subjecteldoni
dc.subjectpullus
dc.subjectanomalus
dc.subjectNew Zealand
dc.subjectLife history
dc.titleLife history variation and diet preference in non-diadromous Otago galaxiids
dc.typeThesis
dc.date.updated2016-10-09T11:31:33Z
dc.language.rfc3066en
thesis.degree.disciplineZoology
thesis.degree.nameMaster of Science
thesis.degree.grantorUniversity of Otago
thesis.degree.levelMasters
otago.openaccessOpen
 Find in your library

Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record