title: Sensory specificity and speciation: a potential neuronal pathway for host fruit odour discrimination in Rhagoletis pomonella.
abstract: Behavioural changes in habitat or mate choice can trigger population divergence, leading to speciation. However, little is known about the neurological bases for such changes. Rhagoletis pomonella (Diptera: Tephritidae) is a model for ecological speciation via host plant shifts. Within the past 180 years, Rhagoletis flies infesting hawthorn (Crataegus spp.) shifted to attack domesticated apple (Malus pumila). The two populations differ in their olfactory preferences for apple versus hawthorn fruit. Here, we looked for patterns of sensory organization that may have contributed to this shift by characterizing the morphology, specificity and distribution of olfactory sensory neurons (OSNs) on the antennae of Rhagoletis responding to host fruit and non-host volatiles. Of 28 OSN classes identified, two colocalized OSN pairs were found that specifically responded to the major behavioural attractant and antagonist volatiles for each fly population. A reversal in the response of these OSNs to fruit volatiles, either through a switch in receptor expression between these paired neurons or changes in neuronal projections in the brain, could therefore account for the behavioural difference between apple and hawthorn flies. The finding supports the hypothesis that relatively minor changes in olfactory sensory pathways may contribute to rapid host shifting and divergence in Rhagoletis.
authors.affiliation: Department of Biological Sciences, University of Notre Dame, South Bend, IN 46556, USA ctait@nd.edu.
authors.forename: Cheyenne
authors.identifier: 0000-0002-1851-8911
authors.initials: C
authors.lastname: Tait
authors.affiliation: Naturalist-Inspired Chemical Ecology, National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bellary Road, Bangalore 560065, India.
authors.forename: Srishti
authors.initials: S
authors.lastname: Batra
authors.affiliation: Naturalist-Inspired Chemical Ecology, National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bellary Road, Bangalore 560065, India.
authors.forename: Sree Subha
authors.initials: SS
authors.lastname: Ramaswamy
authors.affiliation: Department of Biological Sciences, University of Notre Dame, South Bend, IN 46556, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Feder
authors.affiliation: Naturalist-Inspired Chemical Ecology, National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bellary Road, Bangalore 560065, India.
authors.forename: Shannon B
authors.identifier: 0000-0003-4126-7353
authors.initials: SB
authors.lastname: Olsson
mesh_terms: D000818:Animals; D057506:Arthropod Antennae / Q000502:physiology; D005638:Fruit / Q000737:chemistry; D049810:Genetic Speciation; D027845:Malus; D009812:Odorants; D055696:Olfactory Perception; D018034:Olfactory Receptor Neurons / Q000502:physiology*; D033621:Tephritidae / Q000502:physiology*; D055549:Volatile Organic Compounds / Q000737:chemistry
chemical_list: D055549:Volatile Organic Compounds
keywords: chemosensory system; ecological speciation; electrophysiology; host choice; host shifts; phytophagous insects