The evolution of exaggerated male weaponry in New Zealand sheet-web spiders

During my  doctorate, I investigated the evolution and function of exaggerated chelicerae in New Zealand sheet-web spiders (Cambridgea spp.) using a range of morphological, behavioural and phylogenetic techniques in order to compare weapon morphology across different species of the genus and to characterise the way that sexual selection may be acting upon them. My PhD was supervised by Drs Greg Holwell (The University of Auckland) and Cor Vink (Canterbury Museum).

Key research techniques:

  • Studying the role of weapons in male-male contests
    • Field collecting, behavioural observations, animal husbandry, model selection and applying contest assessment models
  • Comparing weapon morphology across closely related species
    • Specimen collection and identification; DNA extracting, PCR, sequencing, editing and tree building in Geneious; Phylogenetic least squares; Morphometrics
  • Analysing chelicerae function and small scale morphology
    • Preparation of arachnids for micro-CT, segmentation of micro-CT scans using AMIRA, analysis of force transduction data
C foliata L Walker

Male sheet-webs spiders (Cambridgea foliata) contesting access to a female (foreground)

Sexual cannibalism in a facultative parthenogen

The dissertation project for my Honours degree aimed to determine whether high or low foraging success of female Springbok mantises (Miomantis caffra) influenced the probabilities of cannibalism and copulation. We found that females on both low and high diets cannibalised prospective mates/meals at a roughly equal rate but that, as the season progressed, females became more likely to copulate with males which suggests that there is still value for females to reproduce sexually rather than entirely depending on parthenogenesis in which this species engaged readily.

Female Springbok mantis and 75% of a male