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245	1	0	_aEvolution of a triplet repeat in a conifer
490	0		_vGenome, 48, p.417-426, 2005
520	3		_aThe opportunity to trace the evolution of a triplet repeat is rare, especially for seed-plant lineages with a well-defined fossil record. Microsatellite PtTX2133 sequences from 18 species in 2 conifer genera were used to calibrate the birth of a CAGn repeat, from its protomicrosatellite origins to its repeat expansion. Birth occurred in the hard-pine genome ~ 136 million years ago, or 14 million generations ago, then expanded as a olymorphic triplet repeat 136-100 million years before a major North American vicariance event. Calibration of the triplet-repeat birth and expansion is supported by the shared allelic lineages among Old and New World hard pines and the shared alleles solely among North American diploxylon or hard pines. Five CAGn repeat units appeared to be the expansion threshold for Old and New World diploxylon pines. Haploxylon pine species worldwide did not undergo birth and repeat expansion, remaining monomorphic, with a single imperfect 198-bp allele. A sister genus, Picea, had only a region of cryptic simplicity, preceding a proto-microsatellite region. The polymorphic triplet repeat in hard pines is older than some long-lived microsatellites reported for reptiles, yet younger than those reported for insects. Some cautionary points are raised about phylogenetic applications for this long-lived microsatellite.
650	1	4	_aGYMNOSPERMS
650	1	4	_aMICROSATELLITE EVOLUTION
650	1	4	_aCLADOGENESIS
650	1	4	_aPHYLOGENETIC ANALYSIS
700	1	2	_aSokol, K.A.
700	1	2	_aWilliams, C.G.
856	4	0	_uhttps://drive.google.com/file/d/1dG_tkcnpHZhpsM0Dp7emvwoA2b-FWMNR/view?usp=drivesdk _zPara ver el documento ingresa a Google con tu cuenta: @cicy.edu.mx
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