Sexual tetramorphism in Thymelaea hirsuta (Thymelaeaceae): morph ratios in open-pollinated progeny |
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Authors: | Bertrand Dommée Andrée Biascamano Nicole Denelle Jean-Louis Bompar John D. Thompson |
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Affiliation: | 1. Centre d'Ecologie Fonctionnelle et Evolutive, Centre National de la Recherche Scientifique, BP 5051, 34033 Montpellier Cedex, France;2. Laboratoire de Systématique et d'Ecologie Méditerranéennes, Institut de Botanique, Université Montpellier II, Sciences et Techniques du Languedoc, 163 rue Auguste Broussonet, 34000 Montpellier, France;3. Laboratoire de Botanique, Institut de Botanique, Université Montpellier II, Sciences et Techniques du Languedoc, 163 rue Auguste Broussonet, 34000 Montpellier, France |
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Abstract: | Natural populations of Thymelaea hirsuta have previously been shown to comprise four distinct sexual morphs: males, females, protogynous individuals, i.e., first female then male, and protandrous individuals, i.e., first male then female. The objective of the present study has been to confirm the genetic basis of this sexual tetramorphism by quantifying morph ratios in the open-pollinated progeny of the four sexual phenotypes growing in a natural population. All four phenotypes were recovered in the progeny of each morph. All observed plants displayed a single sexual phenotype, thus confirming the genetic basis of the tetramorphism. The progeny sex ratios indicate that the genetic determination of sex in this species may be influenced by cytoplasmic factors, while the observed levels of functional female fertility suggest a near-dioecious system. The evolutionary significance of this tetramorphism as a transitional stage in the evolution of dioecy is discussed. |
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