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Molecular systematic study of the Cactaceae: Using chloroplast DNA variation to elucidate Cactus phylogeny
Changes detected in the chloroplast DNA involving structural rearrangements, restriction site variation, and gene sequence variation have provided phylogenetically informative data, useful in the construction of cladograms which infer evolutionary relatedness among the various cactus groups investigated. Expand
Phylogenetic studies of Mammillaria (Cactaceae)--insights from chloroplast sequence variation and hypothesis testing using the parametric bootstrap.
Phylogenies derived from the parsimony and Bayesian analyses indicate that Mammillaria is not monophyletic and that the genus Mammilloydia is embedded within a "core" group of mammillaria species. Expand
Molecular Systematics of Tribe Cacteae (Cactaceae: Cactoideae): A Phylogeny Based on rpl16 Intron Sequence Variation
Parsimony analysis of plastid rpl16 sequences from 62 members of Tribe Cacteae, and four outgroup taxa yielded 1296 equally parsimonious trees of length 666, which established a highly pectinate topology, which delimited clades within the tribe that correspond to several previously considered generic groups. Expand
Phylogeny of the Portulacaceous Cohort Based on ndhF Sequence Data
A molecular phylogeny of the portulacaceous cohort showed that several generic circumscriptions remain inadequate, particularly that of Talinum sensu lato, which was polyphyletic in this analysis, and that all present classifications of the Portulacaceae include demonstrably non-monophyletic tribes. Expand
Karyotypic studies in the genus Echinocereus (Cactaceae) and their taxonomic significance
Robertsonian changes and centric fusion of telocentric chromosomes, are thought to be involved in the existence of homogeneous karyotypes and karyotype asymmetry increases as the chromosome and genome length increases. Expand
Evolution and Systematics
Phylogenetic relationships and patterns of character change in the tribe Lactuceae (Asteraceae) based on chloroplast DNA restriction site variation
The results of this study of chloroplast DNA restriction site variation suggest that rapid diversification played an important role in early stages of the Lactuceae tribe's evolution, and the monophyly of many groups is strongly supported. Expand
Oceanographic and climatic factors influencing breeding and colony attendance patterns of Humboldt penguins Spheniscus humboldti in central Chile
This 2-peak breeding strategy of Humboldt penguins appears to have evolved in response to the more favourable oceanographic and climatic conditions of Peru, where breeding is continuous and not interrupted by rains. Expand
Plasma tocopherol, retinol, and carotenoid concentrations in free-ranging Humboldt penguins (Spheniscus humboldti) in Chile
Both physiologic changes associated with season, and the change in locale may have contributed to the differences seen in the assay means and the number of samples with detectable levels. Expand