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Assessing the patterns and drivers of shape complexity in the amblypygid pedipalp using elliptical Fourier analysis
  • Callum McLean,
  • Russell Garwood,
  • Charlotte Brassey
Callum McLean
Manchester Metropolitan University

Corresponding Author:[email protected]

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Russell Garwood
The University of Manchester
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Charlotte Brassey
Manchester Metropolitan University
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Amblypygids are an arachnid order possessing a unique pair of spined pedipalps: appendages that perform in prey capture, courtship and contest. Pedipalp length, hypothesised to be under sexual selection, varies markedly across amblypygid species, and pedipalp spination, thought to reflect selection for function in prey capture, also differs interspecifically. Differences in pedipalp shape between species may indicate that the relative strength of selection for prey capture and sexual selection vary across the group. However, interspecific differences in pedipalp shape have not been quantified, due to difficulties in identifying homologous features. For the first time, we quantify trends in amblypygid pedipalp shape complexity. We use elliptical Fourier analysis to quantify 2D complexity in pedipalp outlines across eleven species and six genera. We find that complexity significantly decreases as pedipalp length increases. This appears to be driven by relative spine length, suggesting that a trade-off exists between pedipalp length and spination. Furthermore, significant female-biased sexual dimorphism in shape complexity is present in the tibial segment of the amblypygid pedipalp. Our results provide novel insights into the drivers of amblypygid pedipalp evolution, and suggest that a functional trade-off between performance in prey capture and other functions under sexual selection exist in this enigmatic structure.
01 Feb 2021Submitted to Ecology and Evolution
12 Feb 2021Submission Checks Completed
12 Feb 2021Assigned to Editor
16 Feb 2021Reviewer(s) Assigned
10 Mar 2021Review(s) Completed, Editorial Evaluation Pending
12 Mar 2021Editorial Decision: Revise Minor
21 May 20211st Revision Received
26 May 2021Submission Checks Completed
26 May 2021Assigned to Editor
26 May 2021Review(s) Completed, Editorial Evaluation Pending
03 Jun 2021Editorial Decision: Accept