Sarah Mathews

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Dated molecular phylogenies are the basis for understanding species diversity and for linking changes in rates of diversification with historical events such as restructuring in developmental pathways, genome doubling, or dispersal onto a new continent. Valid fossil calibration points are essential to the accurate estimation of divergence dates, but for(More)
Two novelArabidopsis phytochrome genes,PHYD andPHYE, are described and evidence is presented that, together with the previously describedPHYA, PHYB andPHYC genes, the primary structures of the complete phytochrome family of this plant are now known. ThePHYD- andPHYE-encoded proteins are of similar size to the other phytochrome apoproteins and show sequence(More)
Partial sequences of the nuclear gene encoding the photoreceptor phytochrome A (PHYA) are used to reconstruct relationships within Orobanchaceae, the largest of the parasitic angiosperm families. The monophyly of Orobanchaceae, including nonphotosynthetic holoparasites, hemiparasites, and nonparasitic Lindenbergia is strongly supported. Phytochrome A data(More)
An analysis of duplicate phytochrome genes (PHYA and PHYC) is used to root the angiosperms, thereby avoiding the inclusion of highly diverged outgroup sequences. The results unambiguously place the root near Amborella (one species, New Caledonia) and resolve water lilies (Nymphaeales, approximately 70 species, cosmopolitan), followed by Austrobaileya (one(More)
The angiosperm order Malpighiales includes ~16,000 species and constitutes up to 40% of the understory tree diversity in tropical rain forests. Despite remarkable progress in angiosperm systematics during the last 20 y, relationships within Malpighiales remain poorly resolved, possibly owing to its rapid rise during the mid-Cretaceous. Using phylogenomic(More)
Most recent phylogenetic analyses of basal angiosperms have converged on the placement of Amborella as sister to all other extant angiosperms. However, certain recent studies suggest that Amborella and Nymphaeales (water lilies) form a clade sister to all remaining angiosperms or that Nymphaeales alone are the sister to the remaining angiosperms. We report(More)
The family Brassicaceae comprises 3710 species in 338 genera, 25 recently delimited tribes, and three major lineages based on phylogenetic results from the chloroplast gene ndhF. To assess the credibility of the lineages and newly delimited tribes, we sequenced an approximately 1.8-kb region of the nuclear phytochrome A (PHYA) gene for taxa previously(More)
Explanations for biogeographic disjunctions involving South America and Africa typically invoke vicariance of western Gondwanan biotas or long distance dispersal. These hypotheses are problematical because many groups originated and diversified well after the last known connection between Africa and South America (approximately 105 million years ago), and(More)
Effects of taxonomic sampling and conflicting signal on the inference of seed plant trees supported in previous molecular analyses were explored using 13 single-locus data sets. Changing the number of taxa in single-locus analyses had limited effects on log likelihood differences between the gnepine (Gnetales plus Pinaceae) and gnetifer (Gnetales plus(More)
UNLABELLED PREMISE Orobanchaceae are a family of angiosperms that range from fully autotrophic and free-living to completely heterotrophic and dependent on their hosts (holoparasites). Most of the ca. 2060 species are hemiparasites that photosynthesize throughout all or part of their life cycles. Certain family members are ecologically important due to(More)