Evo-devo of novel traits: the genetic basis of butterfly colour patterns

Abstract

The origin and diversification of novel morphological traits is a major research theme in evolutionary developmental biology, or evo-devo. Wing patterns of butterflies, in particular eyespots, are lineage-specific novelties crucial for visual communication. This thesis explores different aspects of eyespot evo-devo, ranging from redeployment of conserved developmental genes in their formation, to the genetic basis of variation in laboratory populations of the model Bicyclus anynana, to evolutionary diversification of eyespot gene networks in a range of butterfly species. We demonstrated that the conserved Hox protein Antennapedia is involved in eyespot formation, in a particular subfamily of Nymphalidae. This highlights the diversification of the regulatory interactions underlying the very first step in eyespot development. We also characterized the segregation and developmental effects of alleles at a single locus that controls eyespot morphology and embryonic segment polarity via the regulation of Wingless signalling. Linkage mapping of this locus revealed that it is a novel, possibly lineage-specific, negative regulator of this signalling pathway. This suggests that not only conserved, but also putative lineage-specific genes can play a role in the formation of novel traits.