Frequency-dependent selection in hermaphrodites: the rule rather than the exception |
| |
Authors: | M. D. ROSS |
| |
Affiliation: | Abteilung für Forstgenetik und Forstpflanzenzüchtung, Universität Göttingen, Büsgenweg 2, D-3400 Göttingen-Weende, Federal Republic of Germany |
| |
Abstract: | It is shown for simple assumptions that frequency-dependent selection in seed plants may have at least three causes, namely: (a) sexual asymmetry; (b) differential genotypic selfing rates; and (c) gene-cytoplasm fertility interactions. Sexual asymmetry is defined as the situation where the ratio of pollen: ovule fertility is not the same for all genotypes or phenotypes in a population. A review of the literature suggests that all three causes of frequency-dependent selection probably occur in nature, and that at least the first cause, sexual asymmetry, is probably widespread in hermaphrodites. It is shown that resource-allocation theory leads to the expectation that sexual asymmetry and, therefore, frequency-dependent selection should be almost universal in hermaphrodite populations which are not largely selfed. A method for obtaining frequency-dependent fitness values is presented and applied to a population of Scots pine ( Pinus sylvestris ) showing strong sexual asymmetry. |
| |
Keywords: | Selection— frequency-dependent selection— sexual asymmetry— selfing— cytoplasmic inheritance— pollen: ovule ratios— resource allocation— Pinus sylvestris— fitness |
|
|