DOI: 10.5061/dryad.bvq83bkc8
title: Olfactory receptor alignments for: Ecological constraints on highly evolvable olfactory receptor genes and morphology in neotropical bats

description: While evolvability of genes and traits may promote specialization during
 species diversification, how ecology subsequently restricts such variation
 remains unclear. Chemosensation requires animals to decipher a complex
 chemical background to locate fitness-related resources, and thus the
 underlying genomic architecture and morphology must cope with constant
 exposure to a changing odorant landscape; detecting adaptation amidst
 extensive chemosensory diversity is an open challenge. In phyllostomid
 bats, an ecologically diverse clade that evolved plant-visiting from an
 insectivorous ancestor, the evolution of novel food detection mechanisms
 is suggested to be a key innovation, as plant-visiting species rely
 strongly on olfaction, supplementarily using echolocation. If this is
 true, exceptional variation in underlying olfactory genes and phenotypes
 may have preceded dietary diversification. We compared olfactory receptor
 (OR) genes sequenced from olfactory epithelium transcriptomes and
 olfactory epithelium surface area of bats with differing diets.
 Surprisingly, although OR evolution rates were quite variable and
 generally high, they are largely independent of diet. Olfactory epithelial
 surface area, however, is relatively larger in plant-visiting bats and
 there is an inverse relationship between OR evolution rates and surface
 area. Relatively larger surface areas suggest greater reliance on
 olfactory detection and stronger constraint on maintaining an already
 diverse OR repertoire. Instead of the typical case in which specialization
 and elaboration are coupled with rapid diversification of associated
 genes, here the relevant genes are already evolving so quickly that
 increased reliance on smell has led to stabilizing selection, presumably
 to maintain the ability to consistently discriminate among specific
 odorants — a potential ecological constraint on sensory evolution.
description: Specimens were collected over the course of five field
 expeditions: two to the Dominican Republic in 2014 and 2015 (collection
 permit VAPB-01436), one to Belize in 2014 (Belize Forestry Department
 Scientific Research and Collecting Permit CD/60/3/14), one to Peru in 2015
 (collection permit 0002287), and one to Costa Rica in 2017 (collection
 permit R-041-2017-OT-CONAGEBIO). All genetic tissue and morphological
 specimens were exported in accordance with research permit and country
 guidelines. Samples were imported in accordance with U.S. Center for
 Disease Control and U.S. Fish & Wildlife guidelines. All specimens
 were collected, handled, and euthanized in accordance with Stony Brook
 University IACUC permit 614763-3 for Peru, and 448712-3 for Costa Rica,
 and Brown University IACUC 1205016 and 1504000134, University of Georgia
 IACUC AUP A2009-10003-0 and A2014 04-016-Y3-A5 for Belize.
 The main olfactory epithelium was dissected, RNA was extracted
 and sequenced, olfactory receptor reading frames were identified, and
 receptors were aligned.
description: These can be opened in a text editor or any phylogenetic
 alignment handling program.