DOI: 10.5061/dryad.gmsbcc2r5
title: Data for: Static allometries do not reflect evolutionary allometry in exaggerated weaponry of male New Zealand sheetweb spiders (Cambridgea spp.)

description: Across the animal kingdom, exaggerated weaponry is frequently used by one
 sex to contest access for potential mates. Within species, if
 disproportionate investment in weaponry confers an advantage to larger
 individuals, this may result in positive static allometry. It is predicted
 that the same selective pressures may also lead to positive evolutionary
 allometry, where larger species bear disproportionately large weapons on
 average, compared with smaller species. However it is unclear whether the
 slopes of species-specific static allometries are steeper among larger
 species, or remain consistent. All adult males across the New Zealand
 sheet-web spider genus Cambridgea bear exaggerated chelicerae which are
 used to compete for control of females’ webs. Here, we characterise the
 distribution of chelicera lengths within each sex of 12 Cambridgea species
 to show that chelicerae almost always exhibit positive static allometry in
 males while female chelicera lengths are consistently isometric. We use
 comparative phylogenetic methods to demonstrate that the slopes of static
 allometries steepen in males of larger species but that the ratio of
 average chelicera length to cephalothorax width is tightly conserved
 across taxa, leading to an isometric evolutionary allometry. While sexual
 selection may drive weapon exaggeration within species, resulting in
 steeper or shallower static allometries, this conservation of relative
 trait size suggests that chelicera length is subject to other stabilising
 selective pressures. Changes to species body plans might be constrained,
 while allowing for disproportionate investment in weapon traits at the
 extremes of body sizes within species.
description: Dataset includes measurements of cephalothorax width (CW) and
 chelicera length (Chl) in millimetres (mm) for adult males (m) and female
 (f) for 12 species of Cambridgea (Desidae), a genus of sheet-web spider
 endemic to Aotearoa New Zealand. Species included in dataset: <em>C.
 ambigua</em>, <em>C. annulata</em>, <em>C.
 antipodiana</em>, <em>C. arboricola</em>, <em>C.
 fasciata</em>, <em>C. foliata, C. obscura, C. pallidula, C.
 peelensis, C. plagiata, C. quadromaculata</em>, and <em>C.
 reinga</em>. Data was collected to examine intra- and inter-specific
 variations in chelicera length. Measured using digital hand callipers on
 specimens collected in the field and accessed from museums including the
 Entomology Research museum, Lincoln University (LUNZ); the Museum of New
 Zealand Te Papa Tongarewa, Wellington (MONZ); the New Zealand Arthropod
 Collection, Landcare research (NZAC); Auckland War Memorial Museum,
 Auckland (AMNZ); and Otago Museum (OMNZ). Field localities and collection
 details included in separate .csv files.  The
 conservation status for the species included in this dataset has been
 designated as "data deficient" by the New Zealand Department of
 Conservation, indicating that these taxa cannot be assessed due to a lack
 of current information about their distribution and abundance. Specimens
 were collected under Department of Conservation permits (Authorizations:
 45478-FAU, 45668-FAU). 
 Reference: Sirvid, P.J.; Vink, C.J.; Fitzgerald, B.M.;
 Wakelin, M.D.; Rolfe, J.; Michel, P. 2020: Conservation status of New
 Zealand Araneae (spiders), 2020. New Zealand Threat Classification Series
 34. Department of Conservation, Wellington. 33 p
description: Cambridgea chelicera length: Length of male and female Cambridgea
 of 12 species (cambridgea_chelicera_length.csv).