Latitudinal cogradient variation of development time and growth rate and a negative latitudinal body weight cline in a widely distributed cabbage beetle

Abstract

The evolutionary and phenotypic responses to environmental gradients are often assumed to be the same, a phenomenon known as “cogradient variation”. However, only a few insect species display cogradient variation in physiological traits along a latitudinal gradient. We found evidence for such a response in the examination of the life history traits of the cabbage beetle Colaphellus bowringi from 6 different geographical populations at 16, 19, 22, 24, 26 and 28°C. Our results showed that larval and pupal development times significantly decreased as rearing temperature increased, and that growth rates were positively correlated with temperature. Body weight tended to decrease with increasing temperature, consistent with the general pattern in ectothermic animals. Larval development time was positively correlated with latitude, whereas the growth rate decreased as latitude increased, showing an example of latitudinal cogradient variation. Body weight significantly decreased with increasing latitude in a stepwise manner, showing a negative latitudinal body weight cline. Females were significantly larger than males, consistent with the female biased sex dimorphism in insects. Body weight tended to decrease with increasing rearing temperature, whereas the differences in sexual size dimorphism (SSD) tended to decrease with increasing body weight, which biased our results toward acceptance of Rensch’s rule. We found that weight loss was an important regulator of SSD, and because male pupae lost significantly more weight at metamorphosis than female pupae, SSD was greater in adults than in pupae. Overall, our data provide a new example that a latitudinal cogradient variation in physiological traits is associated with a negative latitudinal body weight cline.

Cross‐sex genetic correlations and the evolution of sex‐specific local adaptation: Insights from classical trait clines in Drosophila melanogaster

“…Lab‐based studies, which are less common, occasionally report evidence for genetically based divergence in SSD among populations (e.g., nonclinal population differences in SSD in cabbage beetles: Tang et al. ). Other studies report no significant divergence among populations in SSD (e.g., Tesche and Hodges ; Sniegula et al.…”

Summary of the morphological and ecological traits of Central European dung beetles

“…However, such geographic variations at large geographical scales covering more than 10° of latitude (Chown & Gaston ; Tang et al . ) are beyond the scope of our dataset on the Central European dung beetles.…”

Expression of alternative developmental pathways in the cabbage butterfly, Pieris melete and their differences in life history traits

“…We speculate whether an insect species follows the TSR or not may be related to its diapause characteristic. Those species with summer diapause may exhibit the TSR, as indicated by the cabbage beetle, C. bowringi (Tang, He, Chen, Fu, & Xue, ) and this butterfly, P. melete because their reproductive periods occur in the spring and autumn and because these insects have experienced strong selection for body size under relatively low environmental temperatures during the process of evolution. Those species with winter diapause triggered by shortening day lengths combined with high autumn temperatures may exhibit the reverse TSR, as indicated by the Asian corn borer, O. furnacalis (He et al, ; Xiao et al, ), and the rice stem borer, C. suppressalis (Fu et al, ; Huang et al, ).…”

“…We speculate whether an insect species follows the TSR or not may be related to its diapause characteristic. Those species with summer diapause may exhibit the TSR, as indicated by the cabbage beetle, C. bowringi (Tang, He, Chen, Fu, & Xue, 2017) Xiao et al, 2016), and the rice stem borer, C. suppressalis (Fu et al, 2016;Huang et al, 2018). These two species enter winter diapause in response to high autumn temperatures and experience strong selection for body size under warm conditions.…”