Date of Award:

2016

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Advisor/Chair:

David J. Hole

Abstract

Utah lotus (Lotus utahensis Ottley) is a North American legume related to the Eurasian birdsfoot trefoil (L. corniculatus L.), which is an economically valuable forage legume for pastures. Our objectives were to describe the genetic variation within Utah lotus seed collections by measuring adaptive phenotypic traits at three common garden sites in northern Utah, and to determine the genetic structure of populations and the extent of local adaptation through AFLP (amplified fragment length polymorphisms) analysis. We evaluated 14 Utah lotus seed collections from Nevada and Utah, and five seed collections of scrub lotus (L. wrightii (A. Gray) Greene) from Arizona. Significant variation was observed among collections for all phenotypic traits measured. Spring emergence date, flowering date, survival, dry-matter yield, and canopy width discriminated these two species with 100% accuracy. Population structure estimates from 552 AFLP markers of Utah lotus, scrub lotus, and the birdsfoot trefoil check resulted in five genetically differentiated groups. The three primary groups were the three species; within the Utah lotus collections three sub-groups were identified, which corresponded to geographic locations of the collection sites. Two collections of Utah lotus (LU-5 and LU-20) were among the top-tier collections for important phenotypic traits, including dry-matter yield, pod production, number of stems, canopy height, and survival. No significant Pearson’s correlations or canonical correlations were found among the phenotypic traits and environmental characteristics at the collection sites. Significant correlations were detected between genetic and geographic, and phenotypic and geographic distance matrices (r = 0.888, P = 0.001 and r = 0.235, P = 0.044, respectively). No other significant distance matrix correlations were found. Despite the significant isolation by distance correlation, both the genetic and phenotypic evaluations provide little evidence to support local adaptation. Based on these results, one pooled germplasm source of Utah lotus could be developed for use in rangeland restoration and revegetation of the southern Great Basin. Collections LU-5 and LU-20 would be good candidate collections that would represent minimal risk of maladaptation and out-breeding depression with natural populations.

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