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Dispersal strategies, rapid geographic range expansion and their effects on invasive European starlings, Sturnus vulgaris, in South Africa and Australia
Thesis (MSc)--Stellenbosch University, 2015.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2015
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| _version_ | 1867614096521691136 |
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| access_status_str | Open Access |
| author | Phair, David James |
| author2 | Hui, Cang |
| author_browse | Hui, Cang Phair, David James |
| author_facet | Hui, Cang Phair, David James |
| author_sort | Phair, David James |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2015. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/97715 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:46:36.532Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2015 |
| publishDateRange | 2015 |
| publishDateSort | 2015 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/97715 Dispersal strategies, rapid geographic range expansion and their effects on invasive European starlings, Sturnus vulgaris, in South Africa and Australia Phair, David James Hui, Cang Le Roux, Jaco Visser, Vernon Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. Sturnus vulgaris -- Genetics European starling -- Australia European starling -- South Africa Australia -- Environmental conditions South Africa -- Environmental conditions Biological invasions -- Environmental aspects Isolation by distance Sturnus vulgaris -- Dispersal UCTD Thesis (MSc)--Stellenbosch University, 2015. ENGLISH ABSTRACT: Species dispersal can have far reaching effects on morphology, demography and genetics. Specifically dispersal is inherent to two theoretical frameworks, that of Isolation-By-Distance (IBD) and range dynamics. IBD is based on the assumption of a linear increase in pairwise genetic distance with an increase in pairwise Euclidean distance. Despite its ubiquity, IBD theory and its application has been questioned, specifically regarding its relevance in the face of modern techniques and the Mantel test used to assess IBD. I aimed to determine whether IBD patterns follow a linear parametric form or if alternate non-linear forms (exponential, logarithmic or power) apply, and to find predictors of this form and the slope of IBD under linear or logarithmic regressions. I undertook a meta-analysis of 74 studies whereby I fit plots of IBD to four parametric forms and determined the best fit. Furthermore I tested for strong predictors of parametric form, using boosted regression trees and IBD slope, using generalized additive models. I found that the linear parametric form was the least likely fit of the forms detected, although no general pattern was determined. I found that parametric form was significantly predicted by the scale of the study and methodological factors including, sample number and the number of microsatellites assessed. Scale of study also predicted IBD slope, together with the continent of study and the taxonomic class. My findings suggest the occurrence of non-linear IBD patterns and provide a first attempt at determining predictors of these patterns. Within the field of range dynamics a topic receiving great interest is that of spatial sorting, where dispersal enhancing traits assort towards the range edge of expanding populations. This leads to increased dispersal rates developing as species expand, which is most commonly detected in non- native species. Despite the wealth of studies assessing spatial sorting no single study to date has assessed patterns of spatial sorting across multiple continents and invasion contexts. I set out to assess patterns of spatial sorting in the invasive European starling, Sturnus Vulgaris, in both South Africa and Australia. The European starling experiences similar conditions at both these introduction sites and has had similar residence times. Through the use of multi-scale pattern analyses and generalized additive models, I set out to determine whether dispersal linked traits show an increase in size as the distance from introduction site increases. I also assessed non- dispersal linked traits and compared both types of traits to environmental conditions. I found that spatial sorting is occurring in Australia, but not South Africa. The difference detected may be attributed to differences in dispersal rates, clinal variation or environmental heterogeneity or demography. Genetic analyses have found that starlings in South Africa may experience frequent long distance dispersal events which may temper or override spatial sorting patterns. This analysis provides the first attempt at assessing spatial sorting dynamics context across continents and identified a system which can be used to determine drivers of spatial sorting. Overall I identified that dispersal context can modify findings resulting in deviations from expectations given theoretical frameworks. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2015-12-14T07:41:53Z 2015-12-14T07:41:53Z 2015-12 Thesis http://hdl.handle.net/10019.1/97715 en_ZA Stellenbosch University 152 pages : illustrations, maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Sturnus vulgaris -- Genetics European starling -- Australia European starling -- South Africa Australia -- Environmental conditions South Africa -- Environmental conditions Biological invasions -- Environmental aspects Isolation by distance Sturnus vulgaris -- Dispersal UCTD Phair, David James Dispersal strategies, rapid geographic range expansion and their effects on invasive European starlings, Sturnus vulgaris, in South Africa and Australia |
| title | Dispersal strategies, rapid geographic range expansion and their effects on invasive European starlings, Sturnus vulgaris, in South Africa and Australia |
| title_full | Dispersal strategies, rapid geographic range expansion and their effects on invasive European starlings, Sturnus vulgaris, in South Africa and Australia |
| title_fullStr | Dispersal strategies, rapid geographic range expansion and their effects on invasive European starlings, Sturnus vulgaris, in South Africa and Australia |
| title_full_unstemmed | Dispersal strategies, rapid geographic range expansion and their effects on invasive European starlings, Sturnus vulgaris, in South Africa and Australia |
| title_short | Dispersal strategies, rapid geographic range expansion and their effects on invasive European starlings, Sturnus vulgaris, in South Africa and Australia |
| title_sort | dispersal strategies rapid geographic range expansion and their effects on invasive european starlings sturnus vulgaris in south africa and australia |
| topic | Sturnus vulgaris -- Genetics European starling -- Australia European starling -- South Africa Australia -- Environmental conditions South Africa -- Environmental conditions Biological invasions -- Environmental aspects Isolation by distance Sturnus vulgaris -- Dispersal UCTD |
| url | http://hdl.handle.net/10019.1/97715 |
| work_keys_str_mv | AT phairdavidjames dispersalstrategiesrapidgeographicrangeexpansionandtheireffectsoninvasiveeuropeanstarlingssturnusvulgarisinsouthafricaandaustralia |