Natural Genetic Variation and Candidate Genes for Morphological Traits in Drosophila melanogaster

CARREIRA VALERIA; MENSCH JULIÁN; HASSON ESTEBAN; FANARA JUAN JOSÉ

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2016

1932-6203

Body size is a complex character associated to several fitness related traits which show differences between species and within them due to environmental and genetic factors. Latitudinal and altitudinal clines for different morphological traits have been described in several species of Drosophila and different analyses have identified genomic regions associated with such variation in D. melanogaster. However, the genetic basis that orchestrates the morphological variation has been barely studied. Here, our main objective was to study the genetic variation associated to the second chromosome for different morphological traits in natural populations of D. melanogaster located along latitudinal and altitudinal gradients in Argentina. Our results revealed weak clinal signals and a strong effect of the population factor on morphological variation. However, most of the populations showed significant differences among them, suggesting that this factor includes information regarding geographical gradients and genetic aspects. Our analyses also revealed important within-population genetic variation which must be associated to the second chromosome, as the lines are otherwise genetically identical. In order to examine the contribution of different candidate genes to natural variation for these traits, we performed quantitative complementation tests between mutant lines in which the mutated gene is in the second chromosome and six second chromosome substitution lines derived from different populations. The test indicated failure of complementation in all candidate genes studied: invected, Fasciclin 3, toucan, Reticulon-like1, jing and CG14478. These results reveal that natural variation at these loci affects the studied characters suggesting that they are Quantitative Trait Genes for morphological traits. Finally, the different phenotypic outcomes observed suggest that different natural alleles of each gene might contribute to natural variation for morphological traits. However, non-additive effects cannot be ruled out, as wild-derived strains differ at myriad loci in the second chromosome which may interact epistatically with the mutant allele.