Genome scans of variation and adaptive change: extended analysis of a candidate locus close to the phantom gene region in Drosophila melanogaster.
Nucleotide variation in populations originating from the recent range expansion of a species should reflect their adaptation to new habitats as well as their demographic history. A survey of nucleotide variation at 109 noncoding X-chromosome fragments in a European population of Drosophila melanogaster allowed identifying some candidates to have been recently affected by positive selection. Adaptive changes leave a spatial differential footprint that can be used to discriminate among candidates by extending their study to neighboring regions. Here, we surveyed variation at an approximately 190-kb region spanning a locus exhibiting a significantly skewed frequency spectrum. A stretch of approximately 12 kb with reduced variation was detected within a continuously sequenced region that included the focal fragment. Moreover, the regions flanking this stretch exhibited an excess of high-frequency derived variants. Application of maximum likelihood ratio and goodness-of-fit tests suggested that the pattern of variation detected at the studied region (at cytological bands 17C-17D) might have been shaped by a recent selective change, most probably at or around the phantom gene that encodes CYP306A1, a cytochrome P450 enzyme in the ecdysteroidogenic pathway.
Orengo
Dorcas J
DJ
Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain. dorcasorengo@ub.edu
Aguadé
Montserrat
M
D000220:Adaptation, Biological / Q000235:genetics*; D000818:Animals; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000378:metabolism*; D019143:Evolution, Molecular; D014644:Genetic Variation; D049750:Genome, Insect; D006899:Mixed Function Oxygenases / Q000235:genetics*; D009154:Mutation; D011110:Polymorphism, Genetic; D014960:X Chromosome
D029721:Drosophila Proteins; D006899:Mixed Function Oxygenases; C496261:Phm protein, Drosophila