Chrysomela confluens (Leaf Beetle)
Credit: Nathan Rank
about the species
Chrysomela confluens occurs in Western North America from mountainous regions of Utah to Washington. In California, it occurs along the central coast, in the Central Valley, and in the western Sierra Nevada range. Two color forms are found, either a dark (melanic) form with a blue or green sheen or a pale form with black spots. The pale form closely resembles Chrysomela scripta in the eastern USA and related species in Europe. This species feeds on aspen and willow, and has been used in ecological studies of insect-plant interactions. The inheritance of the color polymorphism was investigated by Isabel McCracken at Stanford in 1905, an early example of a trait that was shown to be inherited according to Mendel's principles in animals.
why species was selected
Populations of this species show evidence of adaptation to temperature by varying in the frequency of the dark (melanic) forms depending on local thermal conditions. They also tolerate warmer temperatures than most Chrysomela species, and the genetic differences among California chrysomelids may reveal traits that facilitate adaptation to warmer conditions in natural populations of animals.
