Meeting Abstract
Polyphenic traits develop different final states due to environmental cues. However, it is unclear how developmental processes differ at the level of gene function to achieve distinct morphs. Differences in gene regulation may be particularly important in instances where structures are alternatively patterned, rather than one morph simply lacking the polyphenic structure. The red-shouldered soapberry bug Jadera haematoloma exhibits polyphenic wing morphs in both sexes, where individuals may develop to adulthood with complete wings and functional flight muscles or brachypterous wings with undeveloped flight muscles. Therefore, wing morphs present a combination of alternative patterning and growth, especially within the distal membrane region of the wing. While wings exhibit this polyphenism, other appendages are more canalized in their size. We have explored the biology of the polyphenism using studies of growth and functional tests of gene expression through RNA interference. A steep positive scaling coefficient exists for the wing of both morphs, with modest positive scaling for legs and antennae, and isometric growth for the beak. RNAi was used to knock down several genes with roles in wing patterning and organ size regulation during juvenile-to-adult development. Several genes, including Distal-less are required for growth and patterning within the distal region of the wing. Knock down of the insulin signaling pathway component encoded by FoxO alters the relative size of the body and various appendages. Despite different scaling coefficients, wings and beaks both increased in relative size after FoxO RNAi. This effect was restricted to long-wing morphs. These findings suggest that insulin signaling mediates the relative growth of appendages in this species, and that this influence contributes to polyphenic developmental outcomes.
