Patterns of flowering and sex-ratio variation in the Mediterranean shrub Phillyrea angustifolia (Oleaceae): implications for the maintenance of maleswith hermaphrodites

Citation
Jr. Pannell et F. Ojeda, Patterns of flowering and sex-ratio variation in the Mediterranean shrub Phillyrea angustifolia (Oleaceae): implications for the maintenance of maleswith hermaphrodites, ECOL LETT, 3(6), 2000, pp. 495-502
Citations number
40
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
ECOLOGY LETTERS
ISSN journal
1461-023X → ACNP
Volume
3
Issue
6
Year of publication
2000
Pages
495 - 502
Database
ISI
SICI code
1461-023X(200011)3:6<495:POFASV>2.0.ZU;2-M
Abstract
The Mediterranean shrub Phillyrea angustifolia is one of the few plants tha t display androdioecy, a rare breeding system in which males co-occur with hermaphrodites. However, it has been difficult to account for male frequenc ies previously documented for this species, which have frequently been high er than 0.5. Here we present sex-ratio data from 13 sites in Spain and Port ugal that throw further light on the maintenance of androdioecy in P. angus tifolia. The inferred proportion of males in these populations was around 0 .3, substantially lower that 0.5 and concurring with theoretical prediction s for androdioecy. Differences in the proportion of hermaphrodites in flowe r between "stressed" and "nonstressed" sites suggest the existence of an im portant life-history trade-off between fruit production and the rate at whi ch plants recover from recurrent disturbances such as fire. The reduced fre quency of flowering by hermaphrodites relative to males map help to explain the maintenance of androdioecy in this long-lived, woody species.