Self-incompatibility in the Hawaiian Madiinae (Compositae): An exception to Baker’s Rule
- Author:
-
Carr, Gerald D., Kyhos, Donald W., Powell, Elizabeth A.
- Title:
- Self-incompatibility in the Hawaiian Madiinae (Compositae): An exception to Baker’s Rule
- Periodical:
- Evolution
- Year:
- 1986
- Volume:
- 40
- Pages:
- 430-434
- Subject:
-
Argyroxiphium
Dubautia
Silverswords
- Summary:
- The apparent occurrences of self-incompatibility in Argyroxiphium, Dubautia, and Wilkesia may be interpreted as three exceptions to "Baker's Rule." However, there is considerable cytogenetic and biosystematic evidence that the 28 species of these three genera, in spite of enormous morphological and ecological diversification, are so genetically cohesive that their adaptive radiation from a single colonizing ancestor is very likely. Thus, if anything, these genera very probably do not constitute more than one exception to Baker's observation. This example appears to indicate either that long-distance dispersal and colonization were accomplished at the same time and place by sufficient numbers of individuals to keep a preexisting multiple allelic self-incompatibility mechanism intact or that such a mechanism arose from a single self-compatible progenitor after long distance dispersal to Hawaii. Alternatively, the Hawaiian Madiinae may have been established by a rhizomatous self-incompatible ancestor that could reproduce indefinitely by vegetative means while additional incompatibility alleles accumulated by mutations. The occurrence of rhizomatous self-incompatible species of Madia, Holozonia, and Hermizonia in the mainland Madiinae gives this hypothesis some credibility. Although none of these alternatives discounts the validity of "Baker's Law - as a rule", it seems safe to conclude that they are exceptions.
- Label:
- Silverswords
- URL:
- http://cletus.uhh.hawaii.edu:2075/stable/2408823
- Date:
- 1986
- Collection:
- Periodicals