The reproductive biology of island plants

Abstract

Since the review of the reproductive biology of island plants by Ehrendorfer (1979) three decades ago, there has been a veritable explosion of studies on plants of oceanic islands. Although the primary emphasis, particularly the past two decades, has been on molecular phylogenetics of island lineages (Baldwin et al., 1998; Emerson, 2002), there also has been progress in understanding their reproductive biology. However, the comment by Ehrendorfer (1979, p. 293) about reproductive biology of island plants still applies today: “This is an extensive, fascinating, and complex field of inquiry, still insufficiently covered by relevant work and factual evidence.” And, of course, there is the exhortation by Herbert Baker from his classic paper in Evolution from 1967: “Clearly, the greatest need in this area of biology is for further field and experimental studies (by as many workers as can spare their time) on the reproductive biology of the plants which make up floras of all kinds....” The present review uses Ehrendorfer’s (1979) chapter as a general framework for highlighting progress since that contribution. Also, Barrett (1996) presented a concise review of the reproductive biology and genetics of insular plants, and incorporated several topics (e.g., phylogenetic analyses) not featured in Ehrendorfer (1979). We will use two general approaches in discussing the evolution of the reproductive and pollination biology of island lineages as compared with their presumptive colonizing ancestors. One will be to look at specific islands, and make comparisons between and among them to derive patterns. Another approach will be to discuss specific examples illustrating how plants have adapted, however perfectly or imperfectly, to the situation in the island setting. We will also consider the influence of invasive plants and pollinators on the reproductive biology and conservation of island lineages. Lastly, important areas for future studies will be considered.