Dataset Information

Olfactory receptor repertoire size in dinosaurs.

ABSTRACT: The olfactory bulb (OB) ratio is the size of the OB relative to the cerebral hemisphere, and is used to estimate the proportion of the forebrain devoted to smell. In birds, OB ratio correlates with the number of olfactory receptor (OR) genes and therefore has been used as a proxy for olfactory acuity. By coupling OB ratios with known OR gene repertoires in birds, we infer minimum repertoire sizes for extinct taxa, including non-avian dinosaurs, using phylogenetic modelling, ancestral state reconstruction and comparative genomics. We highlight a shift in the scaling of OB ratio to body size along the lineage leading to modern birds, demonstrating variable OR repertoires present in different dinosaur and crown-bird lineages, with varying factors potentially influencing sensory evolution in theropods. We investigate the ancestral sensory space available to extinct taxa, highlighting potential adaptations to ecological niches. Through combining morphological and genomic data, we show that, while genetic information for extinct taxa is forever lost, it is potentially feasible to investigate evolutionary trajectories in extinct genomes.

SUBMITTER: Hughes GM

PROVIDER: S-EPMC6571463 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Publications

Olfactory receptor repertoire size in dinosaurs.

Hughes Graham M GM Finarelli John A JA

Proceedings. Biological sciences 20190612 1904

The olfactory bulb (OB) ratio is the size of the OB relative to the cerebral hemisphere, and is used to estimate the proportion of the forebrain devoted to smell. In birds, OB ratio correlates with the number of olfactory receptor (OR) genes and therefore has been used as a proxy for olfactory acuity. By coupling OB ratios with known OR gene repertoires in birds, we infer minimum repertoire sizes for extinct taxa, including non-avian dinosaurs, using phylogenetic modelling, ancestral state recon ...[more]

PMID: 31185870

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Project description:For rodents, olfaction is essential for locating food, recognizing mates and competitors, avoiding predators, and navigating their environment. It is thought that rodents may have expanded olfactory receptor repertoires in order to specialize in olfactory behavior. Despite being the largest clade of mammals and depending on olfaction relatively little work has documented olfactory repertoires outside of conventional laboratory species. Here we report the olfactory receptor repertoire of the African giant pouched rat (Cricetomys ansorgei), a Muroid rodent distantly related to mice and rats. The African giant pouched rat is notable for its large cortex and olfactory bulbs relative to its body size compared to other sympatric rodents, which suggests anatomical elaboration of olfactory capabilities. We hypothesized that in addition to anatomical elaboration for olfaction, these pouched rats might also have an expanded olfactory receptor repertoire to enable their olfactory behavior. We examined the composition of the olfactory receptor repertoire to better understand how their sensory capabilities have evolved. We identified 1145 intact olfactory genes, and 260 additional pseudogenes within 301 subfamilies from the African giant pouched rat genome. This repertoire is similar to mice and rats in terms of size, pseudogene percentage and number of subfamilies. Analyses of olfactory receptor gene trees revealed that the pouched rat has 6 expansions in different subfamilies compared to mice, rats and squirrels. We identified 81 orthologous genes conserved among 4 rodent species and an additional 147 conserved genes within the Muroid rodents. The orthologous genes shared within Muroidea suggests that there may be a conserved Muroid-specific olfactory receptor repertoire. We also note that the description of this repertoire can serve as a complement to other studies of rodent olfaction, as the pouched rat is an outgroup within Muroidea. Thus, our data suggest that African giant pouched rats are capable of both natural and trained olfactory behaviors with a typical Muriod olfactory receptor repertoire.

Dataset Information

Olfactory receptor repertoire size in dinosaurs.

Publications

Olfactory receptor repertoire size in dinosaurs.

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