Congress Abstracts - Society for Developmental Biology

evolutionary analysis to study the patterns of sequence evolution of all the FOS-GRN genes during angiosperm evolution. We found
that all the genes of the FOS-GRN are generally conserved, and we also found several gene duplications in certain FOS-GRN nodes.
Our analyses suggest that strong functional constraints have been the main force driving the evolution of the genes in the FOS-GRN,
although some nodes seem to have been more constrained than others. Overall, our results are consistent with a scenario where the
functional (dynamical) independence of a developmental module and the strong interdependence of its components play a major role
in constraining evolutionary rates at the molecular level of individual module components.
Program/Abstract # 273
Of Butterfly Wings and Hopeful Monsters: the loci of discrete evolution
Martin, Arnaud (Cornell Univ, USA); Papa, Riccardo (Univ of Puerto Rico-Rio Piedras, Puerto Rico); Orgogozo, Virginie (CNRS,
France); McMillan, Owen (Smithsonian Tropical Research Inst, Puerto Rico); Reed, Robert (Cornell Univ, USA)
Is phenotypic evolution gradual and consisting of many mutations of small effects, or saltational and based on Hopeful Monster
mutations resembling developmental biology experiments? Answering this question empirically requires the identification of the
genes that drive variation in the wild. The wing patterns of Heliconius butterflies are involved in predator avoidance and are a model
of choice for the study of developmental evolution due to their explosive diversity. We fine-mapped two genes responsible for pattern
variation in this genus. Cis- regulatory variants of the transcription factor optix switch color pattern identities prior to pigmentation 1 ,
and cis- regulatory variants of the WntA ligand determine differences in pattern shape 2 . Both genes qualify as genetic hotspots of
evolution since they have been repeatedly involved in driving adaptive phenotypic variation 3 . How widespread is this gene re-use
phenomenon? In a compilation of 1000 alleles that cause phenotypic differences among animals, plants and yeasts 3 , more than 100
hotspot genes drove the repeated evolution of a wide range of traits. While Hopeful Monsters are uncommon, several natural alleles of
large effect have been shown to result from the aggregation of multiple small-effect mutations at the same hotspot locus, thus
reconciling micromutationist models with the empirical observation of large-effect variants. This synthesis suggests that evolution is
repeatable, gradual at the mutational level, and that phenotypic saltation is due to an accumulation of mutations at single genes. 1 Reed
RD et al. 2011 Science 333:1137-1141 2 Martin A et al. 2012 PNAS 109:12632-12637 3 Martin A, Orgogozo V. 2013 Evolution
10.1111/evo.12081
Program/Abstract # 274
The role of toolkit genes in the evolution of complex wing, thorax, and abdominal color patterns in Drosophila guttifera
Werner, Thomas (Michigan Technological University, USA); Shigeyuki, Koshikawa (U of Wisconsin-Madison, USA) Williams,
Thomas (Univ of Dayton, USA); Bollepogu Raja, Komal Kumar (Michigan Technological Univ, USA); Carroll, Sean (Univ of
Wisconsin-Madison, USA)
Animal color patterns such as zebra stripes, leopard spots, and the myriad variants of butterfly wing color patterns are known to play
important ecological and physiological roles in the life of animals and are crucial for the survival of species. Scientists first tried to
solve the secret of animal patterns with mathematical approaches to find models that could explain how these patterns developed. In
1952, Turing proposed the famous reaction-diffusion model in which a short-range acting activator molecule diffuses from a source to
stimulate color production, while a long-range acting inhibitor molecule prevents pigmentation. Using the spectacularly ornamented
fruit fly Drosophila guttifera , we developed a transgenic protocol to study the development and evolution of color patterns. We
identified that the Wingless morphogen had evolved a new function in the D. guttifera lineage by activating the yellow gene on preexisting
structural landmarks on the wing, causing black melanin spots around sensory organs, tips of the veins, and crossveins. We
are currently expanding this work by investigating if the melanin patterns on different body parts of D. guttifera evolved by the same
mechanisms involving Wingless, or if they are a product of convergent evolution. We optimized an in situ hybridization technique for
the developing thorax and abdomen and show that the yellow and tan genes are expressed in identical patterns precisely
foreshadowing the four longitudinal melanin stripes on the thorax and the six rows of abdominal spots that decorate the body of the
adult D. guttifera fly. We will use the in situ hybridization technique to identify candidate regulators that govern the complex yellow
and tan expression patterns.
Program/Abstract # 275
Insights into origin of new elements in the Dorso-Ventral patterning network in dipterans.
Hodar, Christian; Cambiazo, Veronica (INTA - Universidad de Chile - CRG , Chile)
Evolutionary changes of Dorso-Ventral patterning network (DVN) among Diptera, results in morphology changes of the embryonic
ectoderm. Thus, Drosophila species differentiate a single extra-embryonic membrane, the amnioserosa (AS), in contrast to the amnion
and serosa observed in lower dipterans. This transition might have involved the recruitment of new genes to the network. Some
components of the DVN have been compared between Drosophila and other lower dipterans, which shared a common ancestor 150-
200My ago but, since AS origin was estimated ~100My ago and Drosophila radiation occurs after that event, the question then arises
as to if members of the DV network are novelties in Drosophila lineages or they appear concomitant with the amnioserosa origin.
Using RNA sequencing of early embryos of Musca domestica (~100My of divergence with D. melanogaster) we searched orthologs
of DVN to determinate whether their expression correlated with amnioserosa origin. We identified an ortholog for D. melanogaster
CG6234 gen, which until now had been only found in Drosophilidae group and loss-of-function of this gene results in AS alterations.
In situ hybridizations (ISH) in whole-mount embryos reveal a conserved temporal and spatial expression of CG6234 mRNA.
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