Allometric engineering

Examples and application

Lack's hypothesis

Allometric engineering has been used to test David Lack's hypothesis in the lizard Sceloporus occidentalis. In this study, two populations were "engineered" to fit the morphology of the other by manipulating egg yolk quantity, removing effect of size difference between groups. After manipulation, they found that speed was inversely proportional to body size.

Nature versus nurture

Maternal investment was "allometrically engineered" by surgically removing an ovary in cockroaches (Diploptera punctata). This effectively reduced number of progeny and increased resource allocation to each offspring. They coupled this manipulation with group effects (faster development in large groups), and found that maternal investment can overcome group effect.

Sexual selection

The male long-tailed widowbird (Euplectes progne) has exceptionally long tail feathers roughly half a meter in length. Male tail feathers were cropped and glued and those with artificially enhanced tail lengths secured the most matings, demonstrating female preference. In the fruit fly Drosophila melanogaster, the posterior lobe of the male genitalia is thought to be used by females to recognize conspecifics. The slope scaling relationship between the lobe and the body is very flat, so that lob size is more-or-less the same size regardless of body size. This is consequence of reduced expression of the forkhead transcription factor FOXO . Increasing expression of FOXO in the male genitalia alone reduces the size of the lobe and reduces male mating success . This demonstrates that the flat scaling of genital size maintains mating success in male flies.

Natural selection

The fly Zonosemata vittigera has a banding pattern on its wings that was found to mimic movements of a jumping spider. Greene et al. engineered novel phenotypes, breaking correlation between a behavior and morphology, by cutting and transplanting the wings of this fly with the common housefly. This manipulation demonstrated that it was behavior coupled with the banding pattern that deterred jumping spiders from attacking, though not other predators.