Reproductive biology, ecological life history/demography and genetic diversity of the megagenus Astragalus (Fabaceae, Papilionoideae)

Abstract

Astragalus is the largest genus of seed plants; however, information on its reproductive biology and life history is widely scattered in the literature. About 96% of the species are perennials and 4% annuals; many are rare endemics. Astragalus species are obligate or facultative outcrossers, and inbreeding depression is higher in self-compatible (SC) than in self-incompatible (SI) species. The most frequent pollinators are Bombus , Osmia and Anthophora . On average, 48% of ovules produce seeds, and 40% of flowers produce fruits. Seed/ovule and fruit/flower ratios are lower in SC than in SI species. Predispersal insect seed predation ranges from 0 to 93%, and major predators are Acanthoscelides , Bruchophagus and Tychius . Seeds have physical dormancy and typically form a seed bank. C 3 is the only photosynthetic pathway in the genus. Population growth may be cyclic or noncyclic, and genetic diversity of a taxon may or may not be related to size of geographic range.