Do you smell what I smell? Linking inner nose phenotypic traits and their underlying olfactory receptor genes to olfactory performance based on genotype-phenotype associations. A case study in Primates (Mammalia)

• Applicant: Dr. Franziska Wagner
• Subject Area: Systematics and Morphology (Zoology)
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 507060877

The olfactory ability of mammals is difficult to assess based on morphological traits, which are mostly studied apart from the analyses of olfactory receptor (OR) genes. In the present project, we apply comparative genomics to associate the genotype (OR genes) with the phenotype (e.g., morphology) of the nasal region in microsmatic (poor sense of smell) primates to reveal their yet comparatively high sensitivity to odorants despite a reduced nasal region. We apply the innovative phenotyping approach, in that phenotypic traits are given in a numeric code in an online data matrix which includes 45 primate species of 13 families. The primary data (e.g., olfactory epithelium thickness and surface area, neuron density) will be inferred based on a novel application which was developed by my two host researchers: a specimen is first scanned with micro-computed tomography (μCT) or additionally stained with an iodine solution for diceCT and subsequently prepared for histological sectioning. The μCT and diceCT sections of the nasal cavity are then matched with the corresponding digitized histological serial sections to merge individual cell and tissue structures for the reconstruction of an overall virtual 3D model. Morphological and topographical traits are collected based on descriptive data, and morphometric traits by use of Geometric Morphometrics. We further include activity patterns and diets inferred from literature, as they are associated with olfaction and assumed to interact with intranasal morphology, too. The primary data collected on the specimens and the worded literature information on ecological/ethological traits are converted into machine-actionable data. They represent the phenotypes which are associated with the sequenced OR genes (collaboration with geneticists) by use of descriptive and statistical analyses. We consider phylogenetic relationships and apply grundplan reconstruction to explore how the co-evolution between the nose phenotypes and their associated OR genes determine the olfactory ability among primates. We examine evolutionary constraints along selected lineages and their effects on adaptive strategies during ecological niche occupation. By combining two innovative approaches, phenotyping and the fusion of complementary imaging techniques, we provide comprehensive computer-accessible phenotypic data for multidisciplinary research in neontology and paleontology, like ecological interactions, evolutionary patterns, and genotype-phenotype associations. Particularly, the merging of histology with CT data offers so far the most precise examination of structural complexes. It can be transferred to any body part and tissue, and will promote biological and biomedical research.

• DFG Programme: WBP Fellowship
• International Connection: USA
• Hosts: Professorin Valerie Burke DeLeon, Ph.D.; Professor Timothy D. Smith, Ph.D.