Olfaction in whales: Evidence from a young odontocete of the late Oligocene North Sea

Hoch, Ella

doi:10.1080/10292380009380556

Cited by 23 publications

(17 citation statements)

References 53 publications

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“…4). These results are consistent with fossil evidence for independent loss of olfaction in divergent lineages of odontocetes (Kellogg, 1928;Hoch, 2000;Geisler and Sanders, 2003), but larger samples of complete OR genes from multiple species are necessary to further corroborate this hypothesis. Nevertheless, it is evident that pseudogenization has occurred in multiple odontocete OR genes, resulting in mass silencing of a gradually dying gene superfamily.…”

Section: Pseudogene Content Of or Repertoires And The Degradation Of supporting

confidence: 90%

The Vestigial Olfactory Receptor Subgenome of Odontocete Whales: Phylogenetic Congruence between Gene-Tree Reconciliation and Supermatrix Methods

2008

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The macroevolutionary transition of whales (cetaceans) from a terrestrial quadruped to an obligate aquatic form involved major changes in sensory abilities. Compared to terrestrial mammals, the olfactory system of baleen whales is dramatically reduced, and in toothed whales is completely absent. We sampled the olfactory receptor (OR) subgenomes of eight cetacean species from four families. A multigene tree of 115 newly characterized OR sequences from these eight species and published data for Bos taurus revealed a diverse array of class II OR paralogues in Cetacea. Evolution of the OR gene superfamily in toothed whales (Odontoceti) featured a multitude of independent pseudogenization events, supporting anatomical evidence that odontocetes have lost their olfactory sense. We explored the phylogenetic utility of OR pseudogenes in Cetacea, concentrating on delphinids (oceanic dolphins), the product of a rapid evolutionary radiation that has been difficult to resolve in previous studies of mitochondrial DNA sequences. Phylogenetic analyses of OR pseudogenes using both gene-tree reconciliation and supermatrix methods yielded fully resolved, consistently supported relationships among members of four delphinid subfamilies. Alternative minimizations of gene duplications, gene duplications plus gene losses, deep coalescence events, and nucleotide substitutions plus indels returned highly congruent phylogenetic hypotheses. Novel DNA sequence data for six single-copy nuclear loci and three mitochondrial genes (> 5000 aligned nucleotides) provided an independent test of the OR trees. Nucleotide substitutions and indels in OR pseudogenes showed a very low degree of homoplasy in comparison to mitochondrial DNA and, on average, provided more variation than single-copy nuclear DNA. Our results suggest that phylogenetic analysis of the large OR superfamily will be effective for resolving relationships within Cetacea whether supermatrix or gene-tree reconciliation procedures are used.

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Section: Pseudogene Content Of or Repertoires And The Degradation Of supporting

confidence: 90%

The Vestigial Olfactory Receptor Subgenome of Odontocete Whales: Phylogenetic Congruence between Gene-Tree Reconciliation and Supermatrix Methods

2008

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“…In contrast to odontocetes, mysticetes were shown in a recent study to have fully-equipped olfactory nervous system structures and histologically complex olfactory bulbs, indicating that they can smell in air . To explain the ecological reason why olfaction is present in mysticetes but absent in odontocetes, it has widely been considered that the acquisition of echolocation causes a reduction of the importance of olfaction (echolocation-priority hypothesis) (Cave, 1988;Hoch, 2000). However, mysticetes can smell in air, but not underwater , meaning that mysticete olfaction cannot be compensated for by the acquisition of echolocation, i.e., an underwater sonar system.…”

Section: Introductionmentioning

confidence: 98%

Evolutionary changes of the importance of olfaction in cetaceans based on the olfactory marker protein gene

Kishida

Thewissen

2012

Gene

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Odontocetes and mysticetes are two extant suborders of cetaceans. It is reported that the former have no sense of olfaction, while the latter can smell in air. To explain the ecological reason why mysticetes still retain their sense of smell, two hypotheses have been proposed - the echolocation-priority hypothesis, which assumes that the acquisition of echolocation causes the reduction of the importance of olfaction, and the filter-feeder hypothesis, which assumes that olfactory ability is important for filter-feeders to locate their prey because clouds of plankton give off a peculiar odor. The olfactory marker protein (OMP) is almost exclusively expressed in vertebrate olfactory receptor neurons, and is considered to play important roles in olfactory systems. In this study, full-length open reading frames of OMP genes were identified in 6 cetacean species and we analyzed the nonsynonymous to synonymous substitution rate ratio based on the maximum likelihood method. The evolutionary changes of the selective pressures on OMP genes did fit better to the filter-feeder hypothesis than to the echolocation-priority hypothesis. In addition, no pseudogenization mutations are found in all five odontocetes OMP genes investigated in this study. It may suggest that OMP retains some function even in 'anosmic' odontocetes.

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“…odontocete whales [64,65]. Another trait is that the location of any centre that is claimed to genealogically correspond to an insect mushroom body is situated in the most anterior neuromere of the brain or just the rostral brain in those invertebrates that possess asegmental brains, such as nemertean worms, annelids and Platyhelminthes.…”

Section: Introductionmentioning

confidence: 99%

Genealogical correspondence of a forebrain centre implies an executive brain in the protostome–deuterostome bilaterian ancestor

Wolff

Strausfeld

2016

Phil. Trans. R. Soc. B

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One contribution of 16 to a discussion meeting issue 'Homology and convergence in nervous system evolution'. Orthologous genes involved in the formation of proteins associated with memory acquisition are similarly expressed in forebrain centres that exhibit similar cognitive properties. These proteins include cAMP-dependent protein kinase A catalytic subunit (PKA-Ca) and phosphorylated Ca 2þ /calmodulindependent protein kinase II (pCaMKII), both required for long-term memory formation which is enriched in rodent hippocampus and insect mushroom bodies, both implicated in allocentric memory and both possessing corresponding neuronal architectures. Antibodies against these proteins resolve forebrain centres, or their equivalents, having the same ground pattern of neuronal organization in species across five phyla. The ground pattern is defined by olfactory or chemosensory afferents supplying systems of parallel fibres of intrinsic neurons intersected by orthogonal domains of afferent and efferent arborizations with local interneurons providing feedback loops. The totality of shared characters implies a deep origin in the protostomedeuterostome bilaterian ancestor of elements of a learning and memory circuit. Proxies for such an ancestral taxon are simple extant bilaterians, particularly acoels that express PKA-Ca and pCaMKII in discrete anterior domains that can be properly referred to as brains.

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Olfaction in whales: Evidence from a young odontocete of the late Oligocene North Sea

Cited by 23 publications

References 53 publications

The Vestigial Olfactory Receptor Subgenome of Odontocete Whales: Phylogenetic Congruence between Gene-Tree Reconciliation and Supermatrix Methods

The Vestigial Olfactory Receptor Subgenome of Odontocete Whales: Phylogenetic Congruence between Gene-Tree Reconciliation and Supermatrix Methods

Evolutionary changes of the importance of olfaction in cetaceans based on the olfactory marker protein gene

Genealogical correspondence of a forebrain centre implies an executive brain in the protostome–deuterostome bilaterian ancestor

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