Differences in Long-Chained Cuticular Hydrocarbons between Males and Gynes inCataglyphisDesert Ants

Abstract

8Cuticualar hydrocarbons play an important role in chemical communication in social insects, 9 serving, among other things, as nestmate, gender, dominance and fertility recognition cues. In 10 ants, however, very little is known about the precopulatory signals cuticular hydrocarbons carry. 11These signals may serve as affecting sex pheromones and aphrodisiacs or as reliable signals for 12 idiosyncratic traits, which indirectly affect sexual selection. In this study, we examined, for the 13 first time, in the Cataglyphis genus, sex-specific variability in cuticular hydrocarbons. We 14 focused on a species that exhibits split sex-ratio and found significant quantitative differences 15 between virgin queens and their potential mates. In an analyses of both absolute amounts and 16 relative amounts, we found different compounds to be significantly displayed on gynes and 17 drones, suggesting absolute and relative amounts may carry different signals influencing mating 18 behavior and mate choice. We discuss the possible signals advertised by the non-polar fraction of 19 these hydrocarbon profiles. 20 Key Words-Cataglyphis, Sexual selection, Sex-specific cuticular hydrocarbons. 21 103 population was previously described as C. drusus (Eyer et al. 2017) but our recent species 104 delimitation study raised the question of whether C. drusus is separate species or is it the same 105 species as C. niger, because these populations are not differentiated by their nuclear genomic 106 DNA (Reiner-Brodetzki et al. 2018). Colonies of this population are monogyne (headed by a 107 single queen), polyandrous (queens are multiply mated), and monodomous (single nest per 108 colony) (Eyer et al. 2017). We recently reported that this population exhibits split sex-ratio 109 6allocation, that is, colonies produce either gynes or males but never both sexulas (Inbar and 110 Privman 2018). Queens usually mate during the spring and sexuals can be found in nests in early 111 spring. In the present study we used samples from twelve nests, 6 female-producing colonies and 112 6 male-producing colonies, with 1-3 gynes/drones collected from each colony. All sexuals were 113 frozen on the same evening of collection. 114 115 Cuticular hydrocarbon analysis: 116 Whole bodies were individually immersed in hexane, containing 400 ng/µl of tetracosane (C24) 117 as internal standard. Initial analysis was conducted by gas chromatography/mass spectrometry 118 (GC/MS), using a VF-5ms capillary column, temperature-programmed from 60•C to 300•C 119 (with 1 min initial hold) at a rate of 10•C per min, with a final hold of 15 min. Compound were 120 identified according to their fragmentation pattern and respective retention time compared to 121 authentic standards. We identified 34 compounds in gynes and the same 34 compounds in 122 drones. Quantitative analyses were performed by flame ionization gas chromatography 123 (GC/FID), using the above running conditions. Peak integration was performed using the 124 program Galaxie Varian 1.9. 125 126 RESULTS 127

Genomic architecture of nestmate recognition cues in the desert ant

“…See supplementary Figure S3. Of the 171,570 / 171,355 loci analysed, 155,815 / 155,807 were mapped to a linkage group on the genetic map 52 .…”