Candidate genes and SNPs for body size related traits in Drosophila melanogaster

ORTIZ, V. E.; J. J. FANARA; V. P. CARREIRA

Raleigh

Congreso; Evolution Conference; 2014

Society for the Study of Evolution, Society of Systematic Biologists, American Society of Naturalists

Body size is a complex character which is associated to many important fitness related traits. In order to study its genetic basis, we analyzed face width (FW), thorax length (TL) and wing length (WL) in 40 lines of the Drosophila Genetic Reference Panel (i.e. isogenic lines of D. melanogaster derived from a natural population whose nuclear genomes were completely sequenced). We identified 19, 20 and 114 Single Nucleotide Polimorphisms (SNPs) associated to variation in FW, TL and WL respectively, most of which are located in intronic and intergenic regions. These candidate SNPs are associated to 18, 15 and 89 genes for FW, TL and WL respectively. Some SNPs are related to more than one candidate gene as well as multiple SNPs affect a single gene in many cases. We found only two genes, A2bp1 and axo, affecting two traits simultaneously (i.e. TL and WL) and no gene affecting all of them at the same time. Furthermore, SNPs affecting both traits simultaneously were different for each gene. These results suggest a low level of pleiotropy regarding the studied characters. The distribution of these genes through the genome departed from a random one as we found far less candidate genes located in the 3R chromosome than expected. Finally, a gene ontology analysis associated 93 annotated genes with 118 terms of Biological Process including anatomical structure morphogenesis, organ development, locomotion, tissue development, imaginal disc morphogenesis and imaginal disc-derived appendage morphogenesis. Most candidate SNPs associated to TL and WL showed sex-specific results although an important number of SNPs were associated to WL variation in both sexes simultaneously. Several of these SNPs are associated to genes as fruitless, which have been related to inter-male aggressive behavior. On the other side, most SNPs associated to FW were related to the SNP by sex interaction, although some of them showed sex-specific results. One of the two genes related to variation in males´s FW, Gr39a, has been associated to courtship behavior in males. Finally, our results confirmed five candidate genes which have been related to different morphological traits in other type of isogenic lines (e.g. CG9171, CG42684, bif, bol and ed), many of which have been associated to inter-male aggressive behavior. These results greatly contribute to the knowledge regarding the genetic basis of body size traits as well as they raise interesting questions concerning its relationship with characters related to sexual behavior.