Heritability of body size matches trait evolution in the range expansion of a biological control agent

The heritability of a trait determines whether selection will lead to a change in that trait. Heritability can be measured through breeding designs where the parents are known and the trait is measured on offspring of known relatedness, such as full siblings and half siblings. During range expansion, individuals at the edge are predicted to evolve higher fecundity and greater dispersal ability than core individuals. In insects, both of these are correlated with larger body size. These data were collected to investigate the genetic variation available for evolution of body size of a beetle introduced to North America for biological control (Diorhabda carinulata). The data consist of measurements of body mass and thorax width of full sibling and half sibling families of D. carinulata from one population at the origin of the range expansion. 

Methods
The data consists of measurements of two traits related to body size: weight at eclosion and thorax width of individual beetles of known parentage in full sibling families, nested into half-sibling families. Weight at eclosion was measured on the day that the beetle emerged as an adult. Thorax width is unlikely to change after eclosion, so it was measured on adults in the weeks after eclosion. Due to experimental constraints, we could not measure thorax width on all individuals, so some individuals are missing this data. Traits were measured on three offspring per full-sibling family, two females and one male. At the time of the measurements, the rearing environment of all full-siblings was identical. At eclosion, beetles were separated and reared separately in individual cups with plenty of food.

Rearing conditions of all beetles were standardized in growth chambers set to long daylengths that would promote reproduction. Beetles were fed ad libitum with fresh tamarisk, the natural food source.

Research was performed in summer of 2019 at Colorado State University, Fort Collins, Colorado, USA in the Agricultural Biology Department.