@article {4411, title = {Evolution of the tan locus contributed to pigment loss in Drosophila santomea: a response to Matute et al.}, journal = {Cell}, volume = {139}, year = {2009}, month = {2009 Dec 11}, pages = {1189-96}, abstract = {

We have shown previously that the loss of abdominal pigmentation in D. santomea relative to its sister species D. yakuba resulted, in part, from cis-regulatory mutations at the tan locus. Matute et al. claim, based solely upon extrapolation from genetic crosses of D. santomea and D. melanogaster, a much more divergent species, that at least four X chromosome regions but not tan are responsible for pigmentation differences. Here, we provide additional evidence from introgressions of D. yakuba genes into D. santomea that support a causative role for tan in the loss of pigmentation and present analyses that contradict Matute et al.{\textquoteright}s claims. We discuss how the choice of parental species and other factors affect the ability to identify loci responsible for species divergence, and we affirm that all of our previously reported results and conclusions stand.

}, keywords = {Animals, Chimera, Chromosomal Proteins, DNA-Binding Proteins, Drosophila, Drosophila Proteins, Evolution, Molecular, Non-Histone, Pigmentation, Species Specificity, X Chromosome}, issn = {1097-4172}, doi = {10.1016/j.cell.2009.11.004}, author = {Rebeiz, Mark and Ramos-Womack, Margarita and Jeong, Sangyun and Andolfatto, Peter and Werner, Thomas and True, John and Stern, David L and Carroll, Sean B} } @article {2468, title = {Rapid evolution of sex pheromone-producing enzyme expression in Drosophila.}, journal = {PLoS Biology}, volume = {7}, year = {2009}, month = {2009 Aug 4}, pages = {e1000168}, abstract = {

A wide range of organisms use sex pheromones to communicate with each other and to identify appropriate mating partners. While the evolution of chemical communication has been suggested to cause sexual isolation and speciation, the mechanisms that govern evolutionary transitions in sex pheromone production are poorly understood. Here, we decipher the molecular mechanisms underlying the rapid evolution in the expression of a gene involved in sex pheromone production in Drosophilid flies. Long-chain cuticular hydrocarbons (e.g., dienes) are produced female-specifically, notably via the activity of the desaturase DESAT-F, and are potent pheromones for male courtship behavior in Drosophila melanogaster. We show that across the genus Drosophila, the expression of this enzyme is correlated with long-chain diene production and has undergone an extraordinary number of evolutionary transitions, including six independent gene inactivations, three losses of expression without gene loss, and two transitions in sex-specificity. Furthermore, we show that evolutionary transitions from monomorphism to dimorphism (and its reversion) in desatF expression involved the gain (and the inactivation) of a binding-site for the sex-determination transcription factor, DOUBLESEX. In addition, we documented a surprising example of the gain of particular cis-regulatory motifs of the desatF locus via a set of small deletions. Together, our results suggest that frequent changes in the expression of pheromone-producing enzymes underlie evolutionary transitions in chemical communication, and reflect changing regimes of sexual selection, which may have contributed to speciation among Drosophila.

}, keywords = {Animal, Animal Communication, Animals, Binding Sites, DNA-Binding Proteins, Drosophila, Drosophila Proteins, Evolution, Fatty Acid Desaturases, Female, Gene Expression Regulation, In Situ Hybridization, Male, Mating Preference, Molecular, Sex Attractants, Sex Characteristics, Sexual Behavior}, issn = {1545-7885}, doi = {10.1371/journal.pbio.1000168}, author = {Shirangi, Troy R and Dufour, H{\'e}lo\"{\i}se D and Williams, Thomas M and Carroll, Sean B} } @article {45753, title = {Pleiotropic functions of a conserved insect-specific Hox peptide motif.}, journal = {Development}, volume = {132}, year = {2005}, month = {2005 Dec}, pages = {5261-70}, abstract = {

The proteins that regulate developmental processes in animals have generally been well conserved during evolution. A few cases are known where protein activities have functionally evolved. These rare examples raise the issue of how highly conserved regulatory proteins with many roles evolve new functions while maintaining old functions. We have investigated this by analyzing the function of the ;QA{\textquoteright} peptide motif of the Hox protein Ultrabithorax (Ubx), a motif that has been conserved throughout insect evolution since its establishment early in the lineage. We precisely deleted the QA motif at the endogenous locus via allelic replacement in Drosophila melanogaster. Although the QA motif was originally characterized as involved in the repression of limb formation, we have found that it is highly pleiotropic. Curiously, deleting the QA motif had strong effects in some tissues while barely affecting others, suggesting that QA function is preferentially required for a subset of Ubx target genes. QA deletion homozygotes had a normal complement of limbs, but, at reduced doses of Ubx and the abdominal-A (abd-A) Hox gene, ectopic limb primordia and adult abdominal limbs formed when the QA motif was absent. These results show that redundancy and the additive contributions of activity-regulating peptide motifs play important roles in moderating the phenotypic consequences of Hox protein evolution, and that pleiotropic peptide motifs that contribute quantitatively to several functions are subject to intense purifying selection.

}, keywords = {Amino Acid Motifs, Animals, Conserved Sequence, Drosophila melanogaster, Drosophila Proteins, Extremities, Genes, Homeobox, Homeodomain Proteins, Phenotype, Sequence Deletion, Transcription Factors}, issn = {0950-1991}, doi = {10.1242/dev.02146}, author = {Hittinger, Chris Todd and Stern, David L and Carroll, Sean B} }