CASTA�EDA, L.E.*; NESPOLO, R.F.; ROFF, D.A.; Univ Austral de Chile; Univ Austral de Chile; Univ of California, Riverside: Dissecting the variance-covariance structure in insect physiology: the multivariate association between metabolism and morphology in the nymphs of the sand cricket (Gryllus firmus)

How is the relationship between morphology and metabolism in arthropods? There exists a clear association of different body parts and specific types of metabolism? Commonly, energy metabolism has been explored in response to different to exogenous source of variation (e.g., feeding, locomotion, temperature). However, because they give insight into the relationship between whole metabolism and lower organizational levels such as organs and tissues, examination of endogenous determinants of metabolism other than body mass is itself very important. For this reason, we were interested in studying the multivariate association of body parts and several aspects of energy metabolism in an insect, the nymphs of the sand cricket, Gryllus firmus. By using a variety of both univariate and multivariate techniques, we explored the resultant variance-covariance matrix to build a path diagram with latent variables. After controlling for body mass, we found a significant canonical correlation between metabolism and morphology. According to the factor loadings and path coefficient, the most important contributions of morphology to the correlation were thorax and abdomen size measures, whereas the most important metabolic contribution was resting metabolism. Activity metabolism was mostly explained by body mass rather body parts, which could be a result of resting rates being chronic consequences of the functioning of the metabolic machinery that the insect must maintain.