Browsing by Subject "Microsatellites"
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Item Diversity of Low Chill Peaches (Prunus persica) from Asia, Brazil, Europe and the USA(2011-08-08) Anderson, Natalie A.One hundred fifty-five peach (Prunus persica) cultivars, from Asia, Brazil, Europe, and the USA, were examined using eleven Simple Sequence Repeats (SSRs) to study the genetic relationships among low chill as compared to high chill peach germplasm. Data was analyzed by NTSYSpc to form a similarity matrix using Nei and Li?s Dice similarity coefficient. This similarity matrix was then subjected to a cluster analysis and a dendrogram was constructed using the UPGMA (Unweighted Pair-Group Method, Arithmetic Mean) method. A wide range of diversity was detected, from 0.33 coefficient of similarity amongst the Thai peaches to 0.97 between two Brazilian peaches. The most distant clusters were the low chill peaches from Thailand and Taiwan and the local cultivars (both fruit and ornamental types) from China. Among the improved germplasm, there were distinct clusters for the Chinese/Japanese cultivars, three clusters for the Brazilian cultivars and one for the cultivars from the USA and Europe. The Brazilian materials clustered according to breeding programs in S?o Paulo and Pelotas reflecting the different sets of local cultivars used in the breeding efforts. The largest group investigated was the European/USA peaches. This group subdivided into three distinct clusters, with a general clustering of the low chill germplasm. The low chill accessions from Asia were genetically distant from the improved low chill peaches from the USA or Brazil. The low chill peaches from the Americas were more closely related to the high chill peaches developed in the USA and China/Japan due to the introgression of this germplasm into a low chill background.Item Population Genetic Analyses of the Baird's Pocket Gopher, Geomys breviceps(2012-10-19) Welborn, SarahThe Baird?s pocket gopher (Geomys breviceps) is a solitary, fossorial rodent found throughout areas of Texas, Arkansas, Oklahoma, and Louisiana. Research focusing on the population genetics of pocket gophers and other species with limited vagility and isolated populations is lacking. Through the use of mitochondrial and microsatellite data, a series of population genetic analyses were completed to better understand the population structure and gene flow among a series of G. breviceps localities. Pocket gophers were captured from five localities in the Brazos Valley and used in this study. Due to the lack of microsatellite loci available for G. breviceps, 10 loci were created for use in this study. Overall estimates from the population genetic analyses showed high levels of gene flow amongst nearby localities with decreasing levels as distance between localities increased. Findings suggest that 2-3 localities located within 2 km of each other function as one genetic cluster thus showing 3-4 total genetic clusters total in this study. Results also suggest that the Baird?s pocket gopher is capable of moving at least 2 km, but further analyses should be completed to better understand dispersal distance.Item Population structure of the American crocodile (crocodylus acutus) in Coiba Island, Panama, inferred from morphometric measurement and microsatellite markers(2010-12) Garcia, Liza M. M.; Densmore, Llewellyn D.; Bradle, Robert D.; Strauss, Richard E.The purpose of this project was to characterize the genetic and morphological composition of Crocodylus acutus in Coiba Island, Panama, and to infer the population structure derived from the genetic variability between the North and South region of the Island as influenced by geographic barriers and proximity to continental Panama. Multivariate analysis of variance (MANOVA) was performed to analyze the morphometric measurements. The MANOVA for the effect of sample site indicate differences between locations (P = 0.010). Regarding morphometric variables, North and South of Coiba Island overlapped in the discriminant space, but individuals in Mainland were slightly separated from the South of Coiba Island. The analysis of molecular variance (AMOVA) reported a variation among populations of 17.04%, and within populations of 82.96% with an Fst of 0.17 (P < 0.01) implying genetic structure between the populations sampled. The Bayesian analysis based on a clustering method for inferring population structure confirmed the subdivision identifying the maximum likelihood in a K = 3. Geographic barriers influenced the genetic and morphometric variation in the populations of C. acutus in Coiba Island, as confirmed by the presence of three subdivisions, the absence of immigrants and the landscape heterogeneity in the Island. This genetic structure should be considered in conservation programs.