منابع مشابه
Rapid hybrid speciation in wild sunflowers.
Hybrid or "recombinational" speciation refers to the origin of a new homoploid species via hybridization between chromosomally or genetically divergent parental species. Theory predicts that this mode of speciation is punctuated, but there has been little empirical evidence to support this claim. Here, we test the hypothesis of rapid hybrid speciation by estimating the sizes of parental species...
متن کاملSunflowers in Lattices
A Sunflower is a subset S of a lattice, with the property that the meet of any two elements in S coincides with the meet of all of S. The Sunflower Lemma of Erdös and Rado [2] asserts that a set of size at least 1 + k!(t − 1)k of elements of rank k in a Boolean Lattice contains a sunflower of size t. We develop counterparts of the Sunflower Lemma for distributive lattices, graphic matroids, and...
متن کاملGenomics of homoploid hybrid speciation: diversity and transcriptional activity of long terminal repeat retrotransposons in hybrid sunflowers.
Hybridization is thought to play an important role in plant evolution by introducing novel genetic combinations and promoting genome restructuring. However, surprisingly little is known about the impact of hybridization on transposable element (TE) proliferation and the genomic response to TE activity. In this paper, we first review the mechanisms by which homoploid hybrid species may arise in ...
متن کاملWilliam Pickles lecture 1989. Seeing sunflowers.
THE clearest memory I have from my first year as a medical student is of a botany practical. We had the task, one sunny Thursday afternoon, of cutting a very thin slice of a sunflower stem, putting it under the microscope and drawing what we saw. In the textbook there was an illustration of what we should expect to see: as I remember, it showed regular, neatly-'packed cells with several smaller...
متن کاملRe-creating ancient hybrid species' complex phenotypes from early-generation synthetic hybrids: three examples using wild sunflowers.
Can the complex phenotypes that characterize naturally occurring hybrid species be re-created in early-generation artificial hybrids? We address this question with three homoploid hybrid species (Helianthus anomalus, Helianthus deserticola, Helianthus paradoxus) and their ancestral parents (Helianthus annuus, Helianthus petiolaris) that are phenotypically distinct and ecologically differentiate...
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ژورنال
عنوان ژورنال: Botanical Gazette
سال: 1919
ISSN: 0006-8071
DOI: 10.1086/332445