Competitive Replacement of Talinum mengesii by T. teretifolium in Granite Outcrop Communities of Georgia

Abstract

The distribution ranges of Talinum mengesii (2n = 24) and T. teretifolium (2n = 48) meet and overlap in the central Piedmont region of Georgia, where both species occur only as members of granite outcrop communities. Plants of the two species frequently occur at the same outcrop sites, and competition for a similar niche leads to the gradual replacement of T. mengesii by T. teretifolium. The latter has a more versatile breeding system (it can both self- and cross-pollinate, while T. mengesii is almost totally dependent on cross-pollination) and greater drought tolerance at a young seedling stage than the former. These factors could account for the observed process of competitive replacement.