Figure 2. gilt expression during development and evolution in the semi-aquatic bugs.

(a) Comparative analysis of gene expression profiles between midlegs and hindlegs during early embryogenesis in Limnoporus dissortis. The transcript corresponding to gilt is encircled. (b) Sequence comparison between L. dissortis and Homo sapiens Gilt proteins. Gilt active site and signature motif are highlighted in red, identical amino acids are in bold. (c) In situ hybridization detecting gilt mRNA expression in the midlegs of an early Limnoporus embryo (48 h: ∼30% development). T1, 2, 3: Thoracic segments 1, 2, 3. (d) Evolution of gilt expression across six semi-aquatic bugs representing four families and both the ancestral and derived leg-length plan. gilt expression in the midlegs is detected in species with derived relative leg length plan and absent in species with the ancestral leg plan. The gain of Ubx in midlegs at the base of the Gerromorpha lineage is indicated with green circle and the evolution of gilt expression at the base of the Gerridae with pink rectangle. Scale bars indicated are body sizes of adult individuals.