St Andrews Research Repository

St Andrews University Home
View Item 
  •   St Andrews Research Repository
  • Biology (School of)
  • Biology
  • Biology Theses
  • View Item
  •   St Andrews Research Repository
  • Biology (School of)
  • Biology
  • Biology Theses
  • View Item
  •   St Andrews Research Repository
  • Biology (School of)
  • Biology
  • Biology Theses
  • View Item
  • Login
JavaScript is disabled for your browser. Some features of this site may not work without it.

Multiple origins of 'Senecio cambrensis' Rosser and related evolutionary studies of British 'Senecio'

Thumbnail
View/Open
PaulAllanAshtonPhDThesis.pdf (40.87Mb)
Date
1991
Author
Ashton, Paul Allan
Supervisor
Abbott, Richard J.
Funder
Natural Environment Research Council (NERC)
Metadata
Show full item record
Altmetrics Handle Statistics
Abstract
The most important finding to emerge from the studies reported in this thesis was the discovery that the newly arisen allopolyploid species, S. cambrensis Rosser, has originated on more than one occasion in Britain. A survey of isozyme variation for acid phosphatase (ACP) and a-esterase (a-EST) in S. cambrensis (2n = 60) and its putative parents, the Oxford Ragwort, Senecio squalidus L. (2n = 20) and the Common Groundsel, S. vulgaris L. (2n = 40), produced clear evidence that the Scottish and Welsh populations of S. cambrensis have separate origins. In addition, isozyme banding patterns for glutamate oxaloacetate transaminase (GOT) indicated that populations of S. cambrensis from Wrexham and Mochdre in N. Wales also represent independent origins of the species in Britain. Extending the isozyme survey to include other populations of the two parental species led to the confirmation that the radiate allele in S. vulgaris has an introgressive origin from S. squalidus. Evidence for this came from an analysis of variation at the Got-1 locus. It was established that the Got-1a allele which is present in British S. squalidus populations at high frequency also occurs in the radiate morph of S. vulgaris, but is virtually absent from the non-radiate morph. The greater allelic variation found at the Got-1 locus in the radiate morph, compared to the non-radiate morph, was considered to be a direct result of this introgression. In contrast, at other loci, the non-radiate morph exhibited greater allelic variation than the radiate morph, despite having a higher level of inbreeding. The reduced level of genetic variation in the radiate variant at these loci is presumed to be due to the recent origin of the radiate morph in Britain. Of additional interest was the finding that S. squalidus contains a low level of genetic variation compared with most other outcrossing species that have been surveyed to date, probably due to a genetic bottleneck experienced by the species during its colonisation of Britain. Nevertheless, the level of variation within S. squalidus was still higher than that observed in the predominantly selfing S. vulgaris. Finally, evidence from the electrophoretic survey has confirmed the close evolutionary relationship of several other members of Senecio section Annui (S. viscosus, S. sylvaticus, S. vulgaris ssp. denticulatus, S. teneriffae and S. vernalis ) to S. vulgaris var. vulgaris and S. squalidus, but has failed to support the hypothesis that S. vulgaris originated from S. vernalis via autopolyploidy.
Type
Thesis, PhD Doctor of Philosophy
Collections
  • Biology Theses
URI
http://hdl.handle.net/10023/14206

Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Advanced Search

Browse

All of RepositoryCommunities & CollectionsBy Issue DateNamesTitlesSubjectsClassificationTypeFunderThis CollectionBy Issue DateNamesTitlesSubjectsClassificationTypeFunder

My Account

Login

Open Access

To find out how you can benefit from open access to research, see our library web pages and Open Access blog. For open access help contact: openaccess@st-andrews.ac.uk.

Accessibility

Read our Accessibility statement.

How to submit research papers

The full text of research papers can be submitted to the repository via Pure, the University's research information system. For help see our guide: How to deposit in Pure.

Electronic thesis deposit

Help with deposit.

Repository help

For repository help contact: Digital-Repository@st-andrews.ac.uk.

Give Feedback

Cookie policy

This site may use cookies. Please see Terms and Conditions.

Usage statistics

COUNTER-compliant statistics on downloads from the repository are available from the IRUS-UK Service. Contact us for information.

© University of St Andrews Library

University of St Andrews is a charity registered in Scotland, No SC013532.

  • Facebook
  • Twitter