In autopolyploids, although the diversity of genetic potential increases by the development of new alleles, as has been shown in Tolmiea
menziesii (Soltis & Rieseberg, 1986) and in Dactylis glomerata (Lum aret & Barrientos, 1990), an autopolyploid has very little chance of becoming established because multivalents form during meiosis, causing partial sterility.
Five of these genera (Bensoniella, Conimitella, Elmera, Tellima, and Tolmiea) are monotypic and restricted in distribution to western North America.
Tolmiea menziesii contains both diploid (2n = 14) and tetrapoloid populations (2n = 28) (Soltis 1984), and both cytotypes were included herein.
A deletion of 12 bp was detected within the ITS-1 region of both populations examined of Conimitella williamsii; a 14-bp deletion was found in the ITS-2 region of both samples of Tolmiea menziesii.
The first group (Group 1), comprises species of Lithophragma, Tellima grandiflora, Bensoniella oregona, Tolmiea menziesii, all species of Heuchera examined, and Mitella pentandra, M.
Both collections of the monotypic Tolmiea appear as the sister to M.
Most of the size variation observed in ITS-1 and ITS-2 for members of the Heuchera group is the result of two relatively large deletions, as interpreted from outgroup comparisons: (1) a 12-bp deletion within ITS-1 of both populations of Conimitella williamsii; and (2) a 14-bp deletion in ITS-2 of both samples of Tolmiea menziesii.
Two such islands of shortest trees were found for the Heuchera group [ILLUSTRATION FOR FIGURES 2, 3 OMITTED], the only differences being the monophyly of Group 2 and placement of Tolmiea. Most of our discussion below of monophyletic groups will be based on the consensus tree of all 112 shortest trees [ILLUSTRATION FOR FIGURE 4 OMITTED]; this is the most conservative approach, as it illustrates relationships observed in all shortest trees.
diversifolia, and Tolmiea emerges from within, or is the sister to the clade containing M.
Based on cpDNA restriction-site data, the Heuchera group comprises two major clades [ILLUSTRATION FOR FIGURE 8 OMITTED]: (1) Bensoniella, Lithophragma, and Tolmiea; (2) Conimitella, Elmera, Tellima, and species of Heuchera, Mitella, and Tiarella.
1991a) and matK sequences (Johnson and Soltis 1994) reveal two major lineages within the Heuchera group: (1) Lithophragma, Bensoniella, and Tolmiea; and (2) all other genera.