Mate guarding, competition and variation in size in male orb-web spiders, Metellina segmentata: A field experiment

John Prenter*, Robert W. Elwood, W. Ian Montgomery

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

In the common orb-web spider Metellina segmentata, males are more powerfully built with longer legs, although females are heavier because of their egg load. Males guard females before attempting to mate, and there is considerable male-male competition because of the male-biased operational sex ratio. We used a field removal experiment to examine (1) seasonal changes in the average morphology of guarding males and (2) whether there is a pool of small males that is excluded from the webs of females. Morphological measures were subjected to a principal components analysis and changes in PC scores were examined for seasonal effects and the effects of previous removal of males. The size of guarding males (PC1) increased over the season, suggesting that smaller males were increasingly excluded from webs, but the condition of guarding males (PC2) decreased, indicating that energy reserves are depleted because the males gain little access to food during the reproductive season. When guarding males were removed, smaller males were able to take up residence. Our results show that large males have a clear advantage in monopolizing females. We discuss the manner in which selection acts to maintain large male size in this spider.

Original languageEnglish
Pages (from-to)1053-1058
Number of pages6
JournalAnimal Behaviour
Volume66
Issue number6
DOIs
Publication statusPublished - Dec 2003

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