Olfactory receptor subgenome and expression in a highly olfactory procellariiform seabird

Abstract

24Procellariiform seabirds are known for their well-developed olfactory capabilities, 25 reflected by their large olfactory bulb to brain ratio and olfactory-mediated behaviors. Many 26 species in this clade use olfactory cues for foraging and navigation, and some species can 27 recognize individual-specific odors. Their genomes and transcriptomes may yield important 28 clues about how the olfactory receptor (OR) subgenome was shaped by natural and sexual 29 selection. In this study, we assembled a high-quality Leach's storm petrel (Oceanodroma 30 leucorhoa) genome to facilitate characterization of the OR repertoire. We also surveyed 31 expressed OR genes through transcriptome analysis of the olfactory epithelium -to our 32 knowledge, the first avian study to interrogate OR diversity in this way. We detected a large 33 number (~61) of intact OR genes, and identified OR genes under positive selection. In 34 addition, we estimated that this species has the lowest proportion (~60%) of pseudogenes 35 compared to other waterbirds studied thus far. We show that the traditional annotation-based 36 genome mining method underestimates OR gene number (214) as compared to copy number 37 analysis using depth-of-coverage analysis, which estimated a total of 492 OR genes. By 38 examining OR expression pattern in this species, we identified highly expressed OR genes, 39 and OR genes that were differentially expressed between age groups, providing valuable 40 insight into the development of olfactory capabilities in this and other avian species. Our 41 genomic evidence is consistent with the Leach's storm petrel's well-developed olfactory 42 sense, a key sensory foundation for its pelagic lifestyle and behavioral ecology. 43 44

The genome of the Balearic shearwater (Puffinus mauretanicus), a Critically Endangered seabird: a valuable resource for evolutionary and conservation genomics

“…The copyright holder for this preprint this version posted December 19, 2021. ; https://doi.org/10.1101/2021.12.17.473171 doi: bioRxiv preprint navigation [58-60], partner recognition and mating [61][62][63], finding their own burrows [64] or foraging [65][66][67][68].…”