How diverse are Annonaceae with regard to pollination?

Abstract

Studies during the last decades on representatives of Annonaceae have revealed their diversification with regard to pollination. Examples are given of species pollinated by beetles (cantharophily), which is the predominant mode of the majority of species worldwide, by small or large beetles (both groups having either diurnal or nocturnal flowers with or without thermogenesis), species pollinated by thrips (Thysanoptera), flies (myiophily and sapromyiophily), cockroaches and even bees (melittophily). Adaptational features of floral structures are compared with the behaviour of flower visitors, emphasizing floral rhythm, flower size, petal thickness, stamen structure and odour production. Anaxagorea, the earliest divergent surviving genus in Annonaceae, exhibits floral characters thought to be basal for the family: tissue-rich thick petals that form a pollination chamber; several Anaxagorea spp. exhibit thermogenesis, emit a fruit-like odour and attract small beetles as pollinators. As cantharophily is plesiomorphic in Anaxagorea and in Annonaceae, characters associated with beetle pollination appear imprinted in members of the whole family. Even non-cantharophilous species retain one or more characteristic features of beetle-pollinated species, such as thick petals, flattened and sclerified connective shields or protogynous dichogamy. © 2012 The Linnean Society of London.