The University of St Andrews

Research@StAndrews:FullText >
Biology (School of) >
Biology >
Biology Theses >

Please use this identifier to cite or link to this item:
This item has been viewed 14 times in the last year. View Statistics

Files in This Item:

File Description SizeFormat
GordonSBrownPhDThesis.pdf1.67 MBAdobe PDFView/Open
Title: Sperm competition and male forceps dimorphism in the European earwig Forficula auricularia (Dermaptera: Forficulina)
Authors: Brown, Gordon S.
Supervisors: Tomkins, Joseph L.
Ritchie, Michael Gordon
Keywords: Male dimorphism
Alternative reproductive tactics
Conditional strategy
European earwig
Forficula auricularia
Sperm competition
Issue Date: 22-Jun-2007
Abstract: The European earwig exhibits a remarkable male-dimorphism in forceps morphology that is associated with alternative reproductive tactics under the control of a conditional evolutionarily stable strategy. Populations on the small, rocky islands of the Farnes off the Northumberland coast are known to sustain populations with dramatically higher morph ratios than observed on the UK mainland. A survey conducted of island and mainland sites around the UK showed that the dimorphic populations of the Farnes are similar to other islands and that mainland populations generally exhibit low morph ratios. Additionally, a correlation between morph ratio and population density was found lending support to the hypothesis that the ESS thresholds that define the morph ratios have diverged through local adaptation. A set of seven microsatellite markers are presented that were developed from a Farne island population of F. auricularia with one additional, previously published locus. These eight markers exhibit genetic variability within and between populations and as such can potentially be applied at a range of scales, from broad-scale phylogeography to within population parentage studies. A phylogeographic study of the UK populations using these markers suggests a single postglacial colonisation from mainland Europe and give further support to the local adaptation hypothesis of ESS threshold evolution. A study of ejaculate size in F. auricularia showed that the males transfer free sperm at a steady rate and that the morphs do not differ in the number of sperm per ejaculate. Measurements of change in body-mass were found to be ineffective measures of ejaculate size, but that macrolabic males lost more weight during copula than brachylabic males. This may be the result of differential investment in accessory ejaculate components between the morphs, as a result of the differing risk of sperm competition.
Description: Some portions of this electronic text have been removed owing to copyright restrictions
Other Identifiers: 
Type: Thesis
Publisher: University of St Andrews
Appears in Collections:Biology Theses

This item is protected by original copyright

This item is licensed under a Creative Commons License
Creative Commons

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.


DSpace Software Copyright © 2002-2012  Duraspace - Feedback
For help contact: | Copyright for this page belongs to St Andrews University Library | Terms and Conditions (Cookies)