High altitude favours long chained cuticular hydrocarbons in Drosophila

Cuticular hydrocarbons (CHCs) are key components of the insect cuticle and
contribute to the wide geographical distribution of this taxon. Many
studies have investigated sex and population differences in CHC profiles,
with these investigations mostly focusing on latitudinal CHC variation,
whereas CHC variation across altitudinal transects is less well-studied.
Here, we tested whether CHC profiles vary along an altitudinal gradient in
the cosmopolitan vinegar fly Drosophila melanogaster. We collected three
populations of D. melanogaster from the Western Himalayas at altitudes
ranging from 760 to 2592 m above sea level and studied their CHC profiles
for standing and plastic differences. We found quantitative differences in
25 CHCs across populations, and at higher elevations, males and females
expressed higher amounts of particular long-chained hydrocarbons. We also
found an overall shift in CHCs in all three populations when flies were
exposed to desiccating conditions. Overall, our findings suggest that
there is an altitudinal cline in CHCs; however, this does not mirror the
well-established latitudinal clines in fly hydrocarbons.