Publication Date

2021

Document Type

Dissertation/Thesis

First Advisor

Naples, Virginia L.

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Biological Sciences

Abstract

Berylmys, the White-toothed rats, and other members of the Rattus sl (Rattus, Maxomys, Leopoldamys, Niviventer, Bandicota, and Sundamys) evolved from 3-5 million years ago during a period of dynamic landscape change in Indochinese south Asia wherein climatically stable, warm forests of Miocene and Pliocene Indochina transitioned to a modern landscape regime. From the late Pliocene through the terminal Pleistocene, climate changes, ecological shifts, rising and falling sea levels, and tectonic uplift drove adaptive radiation within Rattus sl, in complex interactions that are still not completely understood. The goal of this study is to understand species relationships and population structure in Berylmys, establish the timing and mode of species diversification, and understand what environmental factors were important in establishing current species distributions. This study will add to knowledge of how landscape level changes of the last 5 million years influenced evolution in different members of this diverse murid radiation. In this study, metric and geometric morphometric analysis of cranial dimensions were used to define specific and intraspecific relationships. Analysis of mitochondrial CYTB and CO1 genes assessed phylogenetic species-level relationships, population structure, and times of divergence. Species distribution models based on climatic and landscape variables were produced in DIVAGIS. Patterns of phylogeographic evolution seen in Berylmys correlate well with what is known of climate and landscape conditions in south Asia over the past 5 million years and are consistent with an in-situ divergence of a widespread ancestral population. While B. bowersi adapted to occupy edge habitats and seasonal dipterocarp forests across Indochina and into Malaysia, B. berdmorei, B. mackenziei, and B. manipulus originate from ancestral populations remaining in relicts of closed evergreen forest in the south and northwest. The juxtaposition within the same region of evergreen and deciduous broadleaf and dipterocarp forests, within tropical, sub-tropical, and montane climates, made possible by the complex topography of Indochina, has allowed these species to occupy different ecological niches within the same landscape. Finally, molecular and morphometric evidence substantiate the subspecific status of Malaysian B. bowersi, and places into question the existence of vicariant populations of B. mackenziei in southern Vietnam and southern China.

Extent

192 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

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