Joined: June 2007
Although animals display a rich variety of shapes and patterns, the genetic changes that explain how complex forms arise are still unclear. Here we take advantage of the extensive diversity of Heliconius butterflies to identify a gene that causes adaptive variation of black wing patterns within and between species. Linkage mapping in two species groups, gene-expression analysis in seven species, and pharmacological treatments all indicate that cis-regulatory evolution of the WntA ligand underpins discrete changes in color pattern features across the Heliconius genus. These results illustrate how the direct modulation of morphogen sources can generate a wide array of unique morphologies, thus providing a link between natural genetic variation, pattern formation, and adaptation.
|This first discovery of a Wnt-pathway gene driving variation in natural populations complements developmental evolution studies [e.g., the previous reports of wing color patterning by wingless (30, 31)] with one important difference: we show that genetic changes at a Wnt locus itself are responsible for pattern variation. WntA is deployed early during wing development and may determine pattern boundaries and identities rather than acting directly as a melanic activator, as suggested by its complementarity with pattern-specific optix expression at later stages (Fig. 2B). As such, linking a patterning molecule to the evolution of a protean, highly variable trait fills an empirical gap between the genetics of adaptive change (6, 43) and the developmental pathways that generate complex phenotypic diversity (3, 4). Because of its repeated association with mimetic phenotypes in two independent color pattern radiations, cis-regulatory changes of WntA expression also appear to represent a path of least resistance in evolution of novel wing patterns. Spatial shifts of morphogen sources may thus be a key mechanism for generating phenotypic novelty through quantum leaps across the landscape of possible morphologies. |
You're obviously illiterate as hell. Peach, bro.-FtK
Finding something hard to believe based on the evidence, is science.-JoeG
the odds of getting some loathsome taint are low-- Gordon E Mullings Manjack Heights Montserrat
I work on molecular systems with pathway charts and such.-Giggles