Biology Faculty Articles

Title

Olfactory Receptor Subgenomes Linked with Broad Ecological Adaptations in Sauropsida

Document Type

Article

Publication Date

11-2015

Publication Title

Molecular Biology and Evolution

Keywords

Olfactory receptors, Adaptation, Selection, Birds

ISSN

0737-4038

Volume

32

Issue/No.

11

First Page

2832

Last Page

2843

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.

Comments

©The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved

Additional Comments

FCT grant and project #s: SFRH/BD/48518/2008, PEst-C/MAR/ LA0015/2013, PTDC/AAC-AMB/104983/2008 (FCOMP-01-0124-FEDER-008610), PTDC/AAC-AMB/121301/2010 (FCOMP-01-0124-FEDER-019490), PTDC/AAG-GLO/6887/2014; Russian Ministry of Science grant #: 11.G34.31.0068

ORCID ID

0000-0001-7353-8301

ResearcherID

N-1726-2015

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