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ABSTRACT Extant vascular plants comprise three major lineages: Lycophytina, Moniliformopses and Spermatophytata. We have investigated the evolution of body plans of vascular plants using a phylogenetic framework to reconstruct... more
ABSTRACT Extant vascular plants comprise three major lineages: Lycophytina, Moniliformopses and Spermatophytata. We have investigated the evolution of body plans of vascular plants using a phylogenetic framework to reconstruct morphological character state changes. Our phylogenetic definition of body plans is based on synapomorphies of the lineages of extant vascular plants. Fundamental body plan features considered include the structure of meristems, the position of sporangia, spore/pollen wall development, and life ...
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ABSTRACT
The giant African snail, Achatina fulica, followed trails made with the mucus of A. fulica, but did not follow those consisting of mucus from Otala vermiculata. In olfactometer experiments, A. fulica and Helix aperta oriented... more
The giant African snail, Achatina fulica, followed trails made with the mucus of A. fulica, but did not follow those consisting of mucus from Otala vermiculata. In olfactometer experiments, A. fulica and Helix aperta oriented preferentially toward the odor of their own species ...
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A new species of Adiantum is described from California. This species is endemic to northern California and is currently known only from Shasta County. We describe its discovery after first being collected over a century ago and... more
A new species of Adiantum is described from California. This species is endemic to northern California and is currently known only from Shasta County. We describe its discovery after first being collected over a century ago and distinguish it from Adiantumjordanii and Adiantumcapillus-veneris. It is evergreen and is sometimes, but not always, associated with limestone. The range of Adiantumshastense Huiet & A.R.Sm., sp. nov., is similar to several other Shasta County endemics that occur in the mesic forests of the Eastern Klamath Range, close to Shasta Lake, on limestone and metasedimentary substrates.
Group I introns are one of the four major classes of introns as defined by their distinct splicing mechanisms. Because they catalyze their own removal from precursor transcripts, group I introns are referred to as autocatalytic introns.... more
Group I introns are one of the four major classes of introns as defined by their distinct splicing mechanisms. Because they catalyze their own removal from precursor transcripts, group I introns are referred to as autocatalytic introns. Group I introns are common in fungal and protist nuclear ribosomal RNA genes and in organellar genomes. In contrast, they are rare in all other organisms and genomes, including bacteria. Here we report five group I introns, each containing a LAGLIDADG homing endonuclease gene (HEG), in large subunit (LSU) rRNA genes of cyanobacteria. Three of the introns are located in the LSU gene of Synechococcus sp. C9, and the other two are in the LSU gene of Synechococcus lividus strain C1. Phylogenetic analyses show that these introns and their HEGs are closely related to introns and HEGs located at homologous insertion sites in organellar and bacterial rDNA genes. We also present a compilation of group I introns with homing endonuclease genes in bacteria. We h...
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Using DNA sequence data from multiple genes (often from more than one genome compartment) to reconstruct phylogenetic relationships has become routine. Augmenting this approach with genomic structural characters (e.g., intron gain and... more
Using DNA sequence data from multiple genes (often from more than one genome compartment) to reconstruct phylogenetic relationships has become routine. Augmenting this approach with genomic structural characters (e.g., intron gain and loss, changes in gene order) as these data become available from comparative studies already has provided critical insight into some long-standing questions about the evolution of land plants. Here we report on the presence of a group II intron located in the mitochondrial atp1 gene of leptosporangiate and marattioid ferns. Primary sequence data for the atp1 gene are newly reported for 27 taxa, and results are presented from maximum likelihood-based phylogenetic analyses using Bayesian inference for 34 land plants in three data sets: (1) single-gene mitochondrial atp1 (exon+intron sequences); (2) five combined genes (mitochondrial atp1 [exon only]; plastid rbcL, atpB, rps4; nuclear SSU rDNA); and (3) same five combined genes plus morphology. All our ph...
Research Interests: Evolutionary Biology, Genetics, Zoology, Molecular Evolution, Morphology, and 16 moreComparative Study, Bayesian Inference, Phylogeny, Sequence alignment, Maximum Likelihood, Structured data, Gene Order, Molecular Phylogenetics and Evolution, Introns, Ferns, Amino Acid Sequence, Base Sequence, Equisetum, DNA sequence, Mitochondrial Proteins, and Molecular Sequence Data
Most of the 470-million-year history of plants on land belongs to bryophytes, pteridophytes and gymnosperms, which eventually yielded to the ecological dominance by angiosperms 90 Myr ago. Our knowledge of angiosperm phylogeny,... more
Most of the 470-million-year history of plants on land belongs to bryophytes, pteridophytes and gymnosperms, which eventually yielded to the ecological dominance by angiosperms 90 Myr ago. Our knowledge of angiosperm phylogeny, particularly the branching order of the earliest lineages, has recently been increased by the concurrence of multigene sequence analyses. However, reconstructing relationships for all the main lineages of vascular plants that diverged since the Devonian period has remained a challenge. Here we report phylogenetic analyses of combined data--from morphology and from four genes--for 35 representatives from all the main lineages of land plants. We show that there are three monophyletic groups of extant vascular plants: (1) lycophytes, (2) seed plants and (3) a clade including equisetophytes (horsetails), psilotophytes (whisk ferns) and all eusporangiate and leptosporangiate ferns. Our maximum-likelihood analysis shows unambiguously that horsetails and ferns toget...