Variability in the cephalothorax shape within and between populations of the spiny orb weaver spider Gasteracantha kuhli

Abstract

Spiders are dominant sit-and-wait predators, and they are of potential value in biological control by feeding on other insects. The sizes and shapes of the spider's body are considered essential for their survival, especially in prey capture. The cephalothorax of the genus Gasteracantha, for example, is considered not only as ahierarchical status of their predation success but also as a defense mechanism from environmental disturbances. It is believed, therefore, that investigating how populations of a species vary, especially those collected from various geographical locations, is important. Thus, in this study, morphometric variations in the cephalothorax of Gasteracantha kuhli from selected local populations were assessed using relative warp analysis (RWA). Thirty-one landmarks were identified in the cephalothorax; coordinates were taken, Procrustes-transformed, and relative warp analysis was conducted. Results of RWA showed significant population variability in the cephalothorax shapes within and between G. kuhli populations, especially on the spines. The observed morphological differences can be argued to reflect their success on how well they do in their growth, survival, and reproduction in different environments where the spiders were found to dwell and are reflected in their external phenotype.

Keywords

• biological indicator
• environmental disturbances
• morphometric techniques
• predators
• variations