Background: Distributional responses by alpine taxa to repeated, glacial-interglacial cycles throughout the last two million years have signi cantly in uenced the spatial genetic structure of populations. These effects have been exacerbated for the American pika (Ochotona princeps), a small alpine lagomorph constrained by thermal sensitivity and a limited dispersal capacity. As a species of conservation concern, long-term lack of gene ow has important consequences for landscape genetic structure and levels of diversity within populations. Here, we use reduced representation sequencing (ddRADseq) to provide a genome-wide perspective on patterns of genetic variation across pika populations representing distinct subspecies. To investigate how landscape and environmental features shape genetic variation, we collected genetic samples from distinct geographic regions as well as across ner spatial scales in two geographically proximate mountain ranges of eastern Nevada. Results: Our genome-wide analyses corroborate range-wide, mitochondrial subspeci c designations and reveal pronounced ne-scale population structure between the Ruby Mountains and East Humboldt Range of eastern Nevada. Populations in Nevada were characterized by low genetic diversity (=0.0006-0.0009; W =0.0005-0.0007) relative to populations in California (=0.0014-0.0019; W =0.0011-0.0017) and the Rocky Mountains (=0.0025-0.0027; W =0.0021-0.0024), indicating substantial genetic drift in these isolated populations. Tajima's D was positive for all sites (D=0.240-0.811), consistent with recent contraction in population sizes range-wide. Conclusions: Substantial in uences of geography, elevation and climate variables on genetic differentiation were also detected and may interact with the regional effects of anthropogenic climate change to force the loss of unique genetic lineages through continued population extirpations in the Great Basin and Sierra Nevada.

The recommended prosthesis designs investigated in this study proved to be reliable, with encouraging success rates for an observation period of 36 months following placement.

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In Part 1 of this two-part literature review, the biomechanics of cantilever fixed partial dentures are reviewed. Theoretical constructs of implant biomechanics with special emphasis on implant-supported cantilevers are also discussed. Finally, an overview of the literature regarding occlusal forces generated by patients with implant-supported prostheses is presented.

The results of this study indicate that an optimum biomechanical environment should exist when cantilever spans exceeding 7 mm are planned regardless of the number of supporting abutments. Strain transmitted to the crestal bone can be decreased by maximizing the number and anterior-posterior spread of supporting fixtures while minimizing the distance between the distal abutment and its adjacent abutment.

In Part 2 of this literature review, a summary of the literature regarding the determination of acceptable cantilever lengths for fixed implant prostheses is presented. Studies examining the possible effects of biomechanical stress on both the implant prosthesis and the supporting bone are also discussed.

Patients indicated that they (1) were highly satisfied with the final results of the replacements for their natural teeth that were retained or supported by this new implant design, (2) would not hesitate to recommend this form of treatment to their friends and relatives, and (3) would not hesitate to seek the same treatment again if necessary in the future.

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