Generalist and specialist pollination in basal angiosperms (ANITA grade, basal monocots, magnoliids, Chloranthaceae and Ceratophyllaceae): what we know now

摘要

An updated description of the pollination and reproductive biology of basal angiosperms is given to show their principal associations with pollinating agents. The review considers members of the ANITA grade, as well as some basal monocots, the magnoliids, Chloranthaceae and Ceratophyllaceae. Morphological, physiological and behavioral characteristics of flowers and their pollinating insects are evaluated. Based on current evidence, early-divergent angiosperms were and are pollination generalists, even so there has been early specialization for either flies, beetles, thrips or bees. Although there are many tendencies for development from generalist flowers to specialist ones, there are also reversals with the development from specialist flowers to generalist ones. The earliest specialization seems to be fly pollination. Adaptations to more recently evolved insect groups, such as scarab beetles or perfume-collecting euglossine bees, demonstrate that several basal angiosperm lines were flexible enough to radiate into modern ecological niches.