Ecological speciation occurs when populations diverge due to adaptation to different environmental conditions, leading to reproductive isolation. Cuticular hydrocarbons (CHCs) serve dual roles in desiccation resistance and mate choice, making them key traits to investigate in ecological divergence. This thesis examines CHC variation between two populations of Drosophila lummei from Japan and Russia to investigate their role in ecological speciation. Our results showed significant differences in CHC composition between the populations, with Japan exhibiting a greater diversity of CHCs. Desiccation resistance assays showed that the Japan population had higher desiccation resistance compared to the Russia population. However, reciprocal crosses between these populations did not show any significant differences in desiccation resistance, suggesting that the genetic factors effecting desiccation resistance is not sex-linked. Male mate choice assays showed no preference for females of either population, suggesting that CHCs may not influence male mate choice in this species. Additionally, reproductive assays showed that offsprings counts varied across temperature conditions, with Russia D. lummei producing fewer offspring than Japan D. lummei and hybrid crosses. These findings suggest that the CHC variation in D. lummei may be shaped by ecological factors but do not affect mate choice based on our limited experiments. Future research will include incorporating female choice experiments and transcriptomic analyses to determine whether CHC variation in this species affects female choice and the genetic basis underlying this variation. This study provides valuable insights into how environmental pressures may drive divergence in mating traits, contributing to our broader understanding of speciation mechanisms in Drosophila.
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