Examinando por Autor "Ruess, Holly"

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Extended studies of interspecific relationships in Daucus (Apiaceae) using DNA sequences from ten nuclear orthologues
(Oxford University, 2019-09-24) Martínez Flores, Fernando; Crespo, Manuel B.; Geoffriau, Emmanuel; Allender, Charlotte; Ruess, Holly; Arbizu Berrocal, Carlos Irvin; Simon, Philipp W.; Spooner, David M.
Daucus has traditionally been estimated to comprise 21–25 species, but a recent study expanded the genus to c. 40 species. The present study uses ten nuclear orthologues to examine 125 accessions, including 40 collections of 11 species (D. annuus, D. arcanus, D. decipiens, D. durieua, D. edulis, D. gracilis, D. minusculus, D. montanus, D. pumilus, D. setifolius and D. tenuissimus) newly examined with nuclear orthologues. As in previous nuclear orthologue studies, Daucus resolves into two well-defined clades, and groups different accessions of species together. Maximum likelihood and maximum parsimony analyses provide concordant results, but SVD quartets reveals many areas of disagreement of species within these two major clades. With maximum likelihood and maximum parsimony analyses Daucus montanus (hexaploid) is resolved as an allopolyploid between D. pusillus (diploid) and D. glochidiatus (tetraploid), whereas with SVD quartets it is resolved as an allopolyploid between D. glochidiatus and an unknown Daucus sp. We propose the new combination Daucus junceus (Durieua juncea) for a neglected species endemic to the south-western Iberian Peninsula often referred to as D. setifolius, and we place D. arcanus in synonymy with D. pusillus. Three lectotypes are also designated.
Greatly reduced phylogenetic structure in the cultivated potato clade (Solanum section Petota pro parte)
(John Wiley & Sons, 2018-02-15) Spooner, David M.; Ruess, Holly; Arbizu Berrocal, Carlos Irvin; Rodríguez, Flor; Solís Lemus, Claudia
•Premise of the Study: osible ies boundaries of wild and cultivated potatoes are controversial, with osible the taxonomic problems in the cultivated potato clade. We here provide the first in‐depth phylogenetic study of the cultivated potato clade to explore osible causes of these problems. •Methods: We examined 131 diploid accessions, using 12 nuclear orthologs, producing an aligned data set of 14,072 DNA characters, 2171 of which are parsimony‐informative. We analyzed the data to produce phylogenies and perform concordance analysis and goodness‐of‐fit tests. •Key Results: There is good phylogenetic structure in clades traditionally referred to as clade 1+2 (North and Central American diploid potatoes exclusive of Solanum verrucosum), clade 3, and a newly discovered basal clade, but drastically reduced phylogenetic structure in clade 4, the cultivated potato clade. The results highlight a clade of species in South America not shown before, ‘neocardenasii’, sister to clade 1+2, that possesses key morphological traits typical of diploids in Mexico and Central America. Goodness‐of‐fit tests suggest potential hybridization between some species of the cultivated potato clade. However, we do not have enough phylogenetic signal with the data at hand to explicitly estimate such hybridization events with species networks methods. •Conclusions: We document the close relationships of many of the species in the cultivated potato clade, provide insight into the cause of their taxonomic problems, and support the recent reduction of species in this clade. The discovery of the neocardenasii clade forces a reevaluation of a hypothesis that section Petota originated in Mexico and Central America.
Integrated Molecular and Morphological Studies of the Daucus guttatus Complex (Apiaceae)
(BioOne, 2016-06-28) Arbizu Berrocal, Carlos Irvin; Simon, Philipp W.; Martínez Flores, Fernando; Ruess, Holly; Crespo, Manuel B.; Spooner, David M.
In a previous study using 94 nuclear orthologs, we reported the species status of the Daucus guttatus complex to be unresolved, partitioned into three clades. In the present study, a subset of ten of these 94 orthologs was used to infer the phylogeny of the D. guttatus complex and related species. A near parallel set of accessions, planted in a common garden, was used for morphological analyses. The molecular trees are highly resolved for most of the clades, grouping accessions of the D. guttatus complex into four clades. Bayesian concordance analysis and a coalescent approach gave slightly different topologies. Morphological data likewise support four taxa in the complex. Moreover, herbarium research from a companion study informs nomenclature for taxa of the complex. We identify these four clades as D. bicolor, D. conchitae, D. guttatus, and D. setulosus; internested in or among these segregates are the phenetically distinctive species D. glochidiatus, D. involucratus, D. littoralis, and D. pusillus. Our research redefines species variation in the D. guttatus complex, clarifies species names, interspecific relationships, confirms a useful subset of nuclear orthologs for studies of dominant topologies of Daucus, and discovers morphological characters allowing proper identification of the four species of the D. guttatus complex and related species.
Phylogenomics of the Carrot Genus (Daucus, Apiaceae)
(John Wiley & Sons, 2014-10-01) Arbizu Berrocal, Carlos Irvin; Ruess, Holly; Senalik, Douglas; Simon, Philipp W.; Spooner, David M.
•Premise of the study: We explored the utility of multiple nuclear orthologs for the taxonomic resolution of wild and cultivated carrot, Daucus species. •Methods: We studied the phylogeny of 92 accessions of 13 species and two subspecies of Daucus and 15 accessions of related genera (107 accessions total) with DNA sequences of 94 nuclear orthologs. Reiterative analyses examined data of both alleles using ambiguity codes or a single allele with the highest coverage, trimmed vs. untrimmed homopolymers; pure exonic vs. pure intronic data; the use of all 94 markers vs. a reduced subset of markers; and analysis of a concatenated data set vs. a coalescent (species tree) approach. •Key results: Our maximum parsimony and maximum likelihood trees were highly resolved, with 100% bootstrap support for most of the external and many of the internal clades. They resolved multiple accessions of many different species as monophyletic with strong support, but failed to support other species. The single allele analysis gave slightly better topological resolution; trimming homopolymers failed to increase taxonomic resolution; the exonic data had a smaller proportion of parsimony‐informative characters. Similar results demonstrating the same dominant topology can be obtained with many fewer markers. A Bayesian concordance analysis provided an overall similar phylogeny, but the coalescent analysis provided drastic changes in topology to all the above. •Conclusions: Our research highlights some difficult species groups in Daucus and misidentifications in germplasm collections. It highlights a useful subset of markers and approaches for future studies of dominant topologies in Daucus.