Date of Award

2023

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Biological and Environmental Sciences

Department

Biological Sciences

First Advisor

Jacqueline F. Webb

Abstract

In addition to the sensory modalities familiar to humans (vision, hearing, smell, touch and taste), fishes have a flow-sensing system that detects local abiotic and biotic water flows called the lateral line system. The neuromast receptor organs of the lateral line system detect hydrodynamic stimuli and are located either on the skin (superficial neuromasts) or within pored, bony canals associated with the dermatocranial bones (canal neuromasts) or scales. In Manuscripts 1 and 2, the development of the cranial lateral line system in brook trout and how climate change impacts the development of this system are described. The lateral line in brook trout develops slowly over several months in concert with their prolonged early life history. When brook trout are reared at higher temperatures, lateral line development is accelerated and the canal neuromasts are larger. In Manuscript 3, the regional specialization of the lateral line canal morphology and its ontogenetic origin in the silverjaw minnow, Notropis buccatus, are investigated and their development is compared to the development of the fathead minnow, Pimephales promelas, for phylogenetic context. The ventral widened lateral line canals of the silverjaw minnow enclose earlier than the narrow canals of the silverjaw minnow and those of the fathead minnow. Additionally, hundreds of ventrally located superficial neuromasts are present with extraoral taste buds distributed amongst the superficial neuromasts, contributing to regional specialization of the lateral line system. In Manuscript 4, the hypothesis that the regional specialization of the lateral line mediates nocturnal, benthic foraging is tested using behavioral experiments. The sensory modalities hypothesized to mediate prey localization (vision, lateral line, chemoreception) were manipulated using experimental variables of light, chemical ablation of the lateral line system, and the presentation of live and dead prey. In the dark, silverjaw minnows were able to detect and localize live and dead prey using only their chemosensory modalities, which challenges our notion that the regional specialization of the lateral line in silverjaw minnows is primarily beneficial for nocturnal, benthic prey detection. These four manuscripts contribute to our knowledge of how the lateral line system develops, lateral line homologies and insights into lateral line evolution, how increased temperatures from climate change can affect lateral line development, and to what extent particular lateral line morphologies are adaptive for feeding behavior.

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