Date of Graduation

12-2020

Document Type

Thesis

Degree Name

Master of Science in Biology (MS)

Degree Level

Graduate

Department

Biological Sciences

Advisor/Mentor

Douglas, Marlis R.

Committee Member

Douglas, Michael E.

Second Committee Member

Philipp, David P.

Third Committee Member

Pummill, Jeff F.

Keywords

Glyptosternoids; Himalayan Tectonism; Nemacheilidae; Phylogeography; Rheophilic Fishes; Sisoridae

Abstract

Biogeography of the Himalayan region [to include the Qinghai-Tibetan Plateau (QTP)] evolved over a ~30M year span, catalyzed by the collision of the Indian and Eurasian plates. The resulting uplift produced major ecological and climatic effects, that in turn drove the diversification of biodiversity. As a result, the QTP is designated as a global biodiversity hotspot particularly vulnerable to cumulative climatic effects, including shrinking distributions, declining numbers, and local extinctions. Understanding how the biodiversity within the Himalaya/ QTP was established and maintained is a necessary first step in prioritizing conservation efforts.

Fishes in global montane regions, such as the Himalaya, are at an elevated risk to climate change, in that their natural histories reflect adaptations to local conditions such as water temperature and flow regimes. An historic baseline for the specialized freshwater fishes of the region, in tandem with a contemporary understanding of their trajectory, is needed to promote collaboration among conservation and management agencies in regional countries, an activity that is to date unfortunately missing. One approach is to derive an historic baseline for these fishes by quantifying their biogeographies, including their dispersals and diversifications.

My thesis evaluates the phylogenetic relationships within two families of fishes [i.e., Loaches (Nemacheilidae) and Asian catfish (Sisoridae)] whose Grinnellian niches (i.e., their habitat and its accompanying behavioral adaptations) identify them as ‘rheophilic’ (i.e., inhabiting swiftly flowing water). I specifically evaluate the distribution of these fishes within the drainages of Bhutan, where aquatic biodiversity is relatively undefined. The diversification and speciation in both study groups reflect the geomorphic evolution of the Himalaya/QTP. My results indicate Bhutanese drainages maintain undiagnosed variation that is allocated to species-groups within each family.

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