The effect of temperature and wing morphology on quantitative genetic variation in the cricket Gryllus firmus, with an appendix examining the statistical properties of the Jackknife–manova method of matrix comparison

• Published in: Journal of evolutionary biology 2004-11, Vol.17 (6), p.1255-1267
• Main Authors: Bégin, M., Roff, D. A., Debat, V.
• Format: Article
• Language: English
• Subjects: additive genetic variation; Analysis of Variance; Animals; Biological Evolution; Biological variation; body size; Body Weights and Measures; common principal components; Entomology; Environmental Sciences; Evolutionary biology; Florida; G matrix; genetic correlation; Genetic diversity; Genetic Variation; Gryllidae - anatomy & histology; Gryllidae - genetics; Gryllus firmus; heritability; Insects; Matrix; Orthoptera; Phenotype; phenotypic plasticity; Quantitative Trait, Heritable; Temperature; wing dimorphism; Wings, Animal - anatomy & histology
• ISSN: 1010-061X; 1420-9101
• DOI: 10.1111/j.1420-9101.2004.00772.x

We investigated the effect of temperature and wing morphology on the quantitative genetic variances and covariances of five size‐related traits in the sand cricket, Gryllus firmus. Micropterous and macropterous crickets were reared in the laboratory at 24, 28 and 32 °C. Quantitative genetic parameters were estimated using a nested full‐sib family design, and (co)variance matrices were compared using the T method, Flury hierarchy and Jackknife–manova method. The results revealed that the mean phenotypic value of each trait varied significantly among temperatures and wing morphs, but temperature reaction norms were not similar across all traits. Micropterous individuals were always smaller than macropterous individuals while expressing more phenotypic variation, a finding discussed in terms of canalization and life‐history trade‐offs. We observed little variation between the matrices of among‐family (co)variation corresponding to each combination of temperature and wing morphology, with only one matrix of six differing in structure from the others. The implications of this result are discussed with respect to the prediction of evolutionary trajectories.