Award Date


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Biological Science

First Committee Member

Brett Riddle

Second Committee Member

John Klicka

Number of Pages



Pine and oak (pine-oak hereafter) woodlands are some of the most widespread floral communities in North America. They are distributed across the continent at mid-latitudes, but do exist as far north as British Columbia and as far south as Nicaragua. They are also disjunct habitats with distinct regional species assemblages (Eastern North America, Rocky Mountain/Great Basin, Californian, Sierra Nevada/Cascades, and Mexican/Central American [Madrean] assemblages). The division of pine-oak forests into specific regional communities should be reflected by patterns of faunal diversity, if the fauna that inhabit these forests evolved in situ over time in pine-oak forests. In fact this is the case for many pine-oak adapted fauna; however, there are a number of bird species that exhibit widespread distributions across these disjunct pine-oak habitats; In this dissertation, I propose three hypotheses to explain the evolution of the widespread distributions of three common pine-oak birds, the Pygmy Nuthatch (Sitta pygmaea), Mountain Chickadee (Poecile gambeli), and White-breasted Nuthatch (Sitta carolinensis ), and evaluate these three hypotheses through a comparative phylogeographic study of mitochondrial DNA (mtDNA) variation in each of these species. Overall, the genetic structure of pine-oak birds has been shaped by two biogeographic events: the in situ evolution of populations in the isolated regional forests and post-glacial population expansion. However, these studies only represent a tiny portion of the diversity of birds that occupy pine and oak forests in North America. Future study of additional co-distributed species will help determine if the genetic patterns observed in this study are broadly applicable across all pine-oak distributed birds.


Birds; Comparative; Forests; Oak; Phylogeography; Pine; Pine-oak; Poecile Gambeli; Sitta Carolinensis; Sitta Pygmaea

Controlled Subject

Zoology; Ecology

File Format


File Size

3737.6 KB

Degree Grantor

University of Nevada, Las Vegas




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