engleski

Comparative Transcriptomic analyses of Hawaiian epigean and hypogean planthoppers in the genus Oliarus

The Hawaiian cave fauna represent an ideal, and understudied, system for investigating the convergent suite of troglomorphic characters observed in cave-adapted species. In particular, planthoppers in the genus Oliarus are a useful taxonomic group for evolutionary studies of cave adaptation because there are multiple cave-adapted species, exhibiting variations in the degree of troglomorphy, found in caves on multiple islands, allowing for precise estimates of divergence times from surface ancestors. Furthermore, most animal systems to date that have been used for studies of cave adaptation are aquatic. To begin developing Oliarus as a terrestrial model for investigations of cave adaptation, we generated transcriptomic data for two epigean and two subterranean Oliarus species. The two subterranean Oliarus species further represent variation in the degree of troglomorphy, with O. lorettae having reduced eyes and pigmentation in comparison to the completely blind and depigmented O. polyphemus. Comparative analyses among species will target differences in the genes represented in the transcriptome, as well as expression level differences, for major pathways involved in troglomorphic features, such as eyes and pigmentation. In preliminary analyses of just visual transduction cascades, and specifically the visual pigment gene opsin, we found that surface Oliarus species express two visual (Rh4 and Rh6) and two nonvisual (peropsin and pteropsin) opsin genes. Surprisingly, both cave-adapted species also expressed both visual opsin genes. Continuing studies will look at additional visual signal transduction genes, as well as compare expression levels across species.

cave fauna ; planthoppers ; convergent evolution ; transcriptome

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