Olfactory Receptor Subgenomes Linked with Broad Ecological Adaptations in Sauropsida.
Abstract
Olfactory receptors (ORs) govern a prime sensory function. Extant birds have distinct
olfactory abilities, but the molecular mechanisms underlining diversification and
specialization remain mostly unknown. We explored OR diversity in 48 phylogenetic
and ecologically diverse birds and 2 reptiles (alligator and green sea turtle). OR
subgenomes showed species- and lineage-specific variation related with ecological
requirements. Overall 1,953 OR genes were identified in reptiles and 16,503 in birds.
The two reptiles had larger OR gene repertoires (989 and 964 genes, respectively)
than birds (182-688 genes). Overall, birds had more pseudogenes (7,855) than intact
genes (1,944). The alligator had significantly more functional genes than sea turtle,
likely because of distinct foraging habits. We found rapid species-specific expansion
and positive selection in OR14 (detects hydrophobic compounds) in birds and in OR51
and OR52 (detect hydrophilic compounds) in sea turtle, suggestive of terrestrial and
aquatic adaptations, respectively. Ecological partitioning among birds of prey, water
birds, land birds, and vocal learners showed that diverse ecological factors determined
olfactory ability and influenced corresponding olfactory-receptor subgenome. OR5/8/9
was expanded in predatory birds and alligator, suggesting adaptive specialization
for carnivory. OR families 2/13, 51, and 52 were correlated with aquatic adaptations
(water birds), OR families 6 and 10 were more pronounced in vocal-learning birds,
whereas most specialized land birds had an expanded OR family 14. Olfactory bulb ratio
(OBR) and OR gene repertoire were correlated. Birds that forage for prey (carnivores/piscivores)
had relatively complex OBR and OR gene repertoires compared with modern birds, including
passerines, perhaps due to highly developed cognitive capacities facilitating foraging
innovations.
Type
Journal articleSubject
adaptationbirds
olfactory receptors
selection
Acclimatization
Adaptation, Physiological
Alligators and Crocodiles
Animals
Birds
Ecology
Evolution, Molecular
Genetic Variation
Genome
Phylogeny
Receptors, Odorant
Reptiles
Sequence Analysis, DNA
Species Specificity
Turtles
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https://hdl.handle.net/10161/11139Published Version (Please cite this version)
10.1093/molbev/msv155Publication Info
Khan, Imran; Yang, Zhikai; Maldonado, Emanuel; Li, Cai; Zhang, Guojie; Gilbert, M
Thomas P; ... Antunes, Agostinho (2015). Olfactory Receptor Subgenomes Linked with Broad Ecological Adaptations in Sauropsida.
Mol Biol Evol, 32(11). pp. 2832-2843. 10.1093/molbev/msv155. Retrieved from https://hdl.handle.net/10161/11139.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Erich David Jarvis
Adjunct Professor in the Deptartment of Neurobiology
Dr. Jarvis' laboratory studies the neurobiology of vocal communication. Emphasis is
placed on the molecular pathways involved in the perception and production of learned
vocalizations. They use an integrative approach that combines behavioral, anatomical,
electrophysiological and molecular biological techniques. The main animal model used
is songbirds, one of the few vertebrate groups that evolved the ability to learn vocalizations.
The generality of the discoveries is tested in other vocal lear

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