title: Modeling olfactory bulb evolution through primate phylogeny.
abstract: Adaptive characterizations of primates have usually included a reduction in olfactory sensitivity. However, this inference of derivation and directionality assumes an ancestral state of olfaction, usually by comparison to a group of extant non-primate mammals. Thus, the accuracy of the inference depends on the assumed ancestral state. Here I present a phylogenetic model of continuous trait evolution that reconstructs olfactory bulb volumes for ancestral nodes of primates and mammal outgroups. Parent-daughter comparisons suggest that, relative to the ancestral euarchontan, the crown-primate node is plesiomorphic and that derived reduction in olfactory sensitivity is an attribute of the haplorhine lineage. The model also suggests a derived increase in olfactory sensitivity at the strepsirrhine node. This oppositional diversification of the strepsirrhine and haplorhine lineages from an intermediate and non-derived ancestor is inconsistent with a characterization of graded reduction through primate evolution.
authors.affiliation: Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, New York, United States of America.
authors.forename: Steven
authors.initials: S
authors.lastname: Heritage
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005580:Fossils; D006801:Humans; D008954:Models, Biological; D008957:Models, Genetic; D009830:Olfactory Bulb / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*; D010802:Phylogeny; D011323:Primates; D012903:Smell