Graduation Date

Fall 2020

Document Type

Thesis

Program

Master of Science degree with a major in Biology

Committee Chair Name

John Reiss

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Micaela Szykman Gunther

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Justus Ortega

Third Committee Member Affiliation

HSU Faculty or Staff

Fourth Committee Member Name

Sharyn Marks

Fourth Committee Member Affiliation

HSU Faculty or Staff

Subject Categories

Biology

Abstract

Morphology is the physical expression of a species’ evolutionary history and adaptation to its environment and as such is tied to ecology. Salamander larvae have historically been separated into "pond-type" and "stream-type" groups based on their morphology, however no studies have been performed quantifying the relationship between morphology and ecology. In this study I utilized in-situ behavioral observations, morphological measurements, and in-lab performance tests of Dicamptodon tenebrosus (stream-type) and Ambystoma gracile (pond-type) to examine the relationship between salamander larval morphology and ecology. In the field, behavior was video recorded during nighttime surveys; afterwards animals were captured and limb measurements were taken. Flow resistance was measured in the lab using a flow chamber and water velocity meter. Swim escapes were video recorded in lab trials and analyzed using video analysis software. In the field, aquatic walking was the predominant form of movement observed in D. tenebrosus, constituting 98.1 percent of all movements; by contrast, aquatic walking made up only 65.4 percent of all movements in A. gracile. Aquatic walking was correlated with more robust forelimbs with a smaller length:width ratio. Swimming was correlated with slender forelimbs with a larger length:width ratio. Forelimb ratio, hindlimb ratio, and caudal fin area were all significantly different between species. Of the fourteen muscles measured, seven were significantly heavier in relative mass in D. tenebrosus. Specifically, muscles that are used in moving the animals forward or closer to the substrate. Dicamptodon tenebrosus were significantly more adept at resisting flows than A. gracile. There was no significant difference in mean swim escape velocities between A. gracile and D. tenebrosus. However, there was a significant difference in variability of swim escape, with D. tenebrosus more variable. These results support the hypothesis that the salamander larval morphotypes are connected to their ecology by behavior and performance. The larval types are not just morphotypes, they are ecomorphotypes.

Citation Style

APA

Included in

Biology Commons

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