Color and wing size: identifying targets of sexual selection in Drosophila melanogaster

Abstract: This study explores the relationship between wing size, coloration, and reproductivesuccess in Drosophila melanogaster, fruit flies. Sexual selection, a key aspect ofevolutionary biology, often involves visual signaling as a means of displaying geneticinformation. The study aims to identify the morphological traits targeted by sexualselection, specifically examining the hypotheses that both wing size and coloration(thin-film interference patterns) influences reproductive success, and that these traitsare correlated. Data was collected from standardized images of 229 fruit flies thatwere used in a competitive mating assay, and the analysis included color analyses inFiji (ImageJ) to obtain red, green, and blue (RGB) values, as well as sizemeasurements in both vertical and horizontal size dimensions for one wing from eachfly. Statistical analyses, including correlation analysis and multiple regression inSPSS, were conducted to examine the relationships between morphological aspects,color, and mating success in the competitive mating assay. Results indicate asignificant relationship between horizontal wing length and male reproductivefitness, suggesting that larger wings may confer advantages in mate choice andreproductive success for males. Phenotypic selection analysis indicated thathorizontal wing length is under significant directional selection independent of wingcoloration, which was not subject to significant selection. The correlation analysisrevealed a weak but significant correlation between wing size and average coloration.Sexual dimorphism in wing dimensions was observed, with females exhibiting largerwings than males. The study suggests that coloration may be influenced by wing size,raising questions about the causal relationship between wing size, coloration, andreproductive success. Importantly, this study suggests that wing size may be a moreimportant target of selection than wing color, suggesting that past findings of sexualselection on color without consideration of wing size or shape may be premature.