The rapid warming of the Earth caused by anthropogenic factors has profound long-term implications for preventing pests and controlling vector-borne diseases. Put simply, Arthropods, ectotherms animals, do better in a warmer world. One of the advantages of a more hospitable environment is spreading geographically to establish new niches. However, appropriate communication both within and between individuals is crucial for successful niche realization, and one of the most ancient ways of communication occurs via chemicals and chemoreception. This project will examine chemosensory adaptations to specialized lifestyles in two arthropods as biological models. First, Ixodes ricinus (Chelicerata) is a vector for multiple tick-borne diseases common in Europe and, as a result, has a significant impact on public health. Despite their epidemiological importance, there is still limited knowledge of the chemosensory system of this species, and thus a poor understanding of host-seeking behavior and chemical ecology. By a comprehensive phylogenetic analysis and comparative genomics approaches, we will investigate how the chemosensory receptor genes are conserved or diversified in seven tick species among twelve tick species. In addition, we have sequenced and analyzed the transcriptomes of the mouthparts of the tick I. ricinus to identify candidate gustatory and olfactory receptor genes and compare their expression levels in male and female ticks. The highly abundant chemosensory receptor genes will then be cloned and functionally characterized in the Xenopus oocyte heterologous expression system. This project aims to perform a comparative genomic and transcriptomic analysis of multiple tick species, integrating genome quality assessment, orthology inference, phylogenetic reconstruction, gene family evolution, and expression quantification.