Evolutionary steps in the reproductive biology of Annonaceae

Abstract

-Flowers of Annonaceae are characterized by fleshy petals, many stamens with hard connective shields and numerous carpels with sessile stigmas often covered by sticky secretions. The petals of many representatives during anthesis form a closed pollination chamber. Protogynous dichogamy with strong scent emissions especially during the pistillate stage is a character of nearly all species. Scent emissions can be enhanced by thermogenesis. The prevailing reproductive system in the family seems to be self-compatibility. The basal genus Anaxagorea besides exhibiting several ancestral morphological characters has also many characters which reappear in other genera. Strong fruit-like scents consisting of fruit-esters and alcohols mainly attract small fruit-beetles (genus Colopterus, Nitidulidae) as pollinators, as well as several other beetles (Curculionidae, Chrysomelidae) and fruit-flies (Drosophilidae), which themselves gnaw on the thick petals or their larvae are petal or ovule predators. The flowers and the thick petals are thus a floral brood substrate for the visitors and the thick petals of Anaxagorea have to be interpreted as an antipredator structure. Another function of the closed thick petals is the production of heat by accumulated starch, which enhances scent emission and provides a warm shelter for the attracted beetles. Insight into floral characters and floral ecology of Anaxagorea, the sister group of the rest of the Annonaceae, is particularly important for understanding functional evolution and diversification of the family as a whole. As beetle pollination (cantharophily) is plesiomorphic in Anaxagorea and in Annonaceae, characters associated with beetle pollination appear imprinted in members of the whole family. Pollination by beetles (cantharophily) is the predominant mode of the majority of species worldwide. Examples are given of diurnal representatives (e.g., Guatteria, Duguetia, Annona) which function on the basis of fruit-imitating flowers attracting mainly fruit-inhabiting nitidulid beetles, as well as nocturnal species (e.g., large-flowered Annona and Duguetia species), which additionally to most of the diurnal species exhibit strong flower warming and provide very thick petal tissues for the voracious dynastid scarab beetles (Dynastinae, Scarabaeidae). Further examples will show that a few Annonaceae have adapted in their pollination also to thrips, flies, cockroaches and even bees. Although this non-beetle pollinated species have adapted in flower structure and scent compounds to their respective insects, they still retain some of the specialized cantharophilous characters of their ancestors. Index terms: Floral biology, pollination, cantharophily, dichogamy.A EVOLUÇÃO DA BIOLOGIA REPRODUTIVA DE ANNONACEAE RESUMO -As flores de Annonaceae são caraterizadas por pétalas carnosas, muitos estames com conectivos duros em forma de escudo e numerosos carpelos com estigmas sésseis que produzem exsudados pegajosos. As pétalas de muitas espécies formam uma câmara de polinização durante a...

Contrasting pollination ecology ofDisepalumspecies (Annonaceae): evolutionary loss of the floral chamber and partial breakdown of protogyny associated with a shift in pollination system

“…: Gottsberger, Meinke & Porembski, ]. This change in flowering rhythm is probably an adaptation to the activity patterns of the pollinators, thereby increasing pollination efficiency (Gottsberger, ): as flies are less regular in their floral visits and often only stay on the flower for a brief time (Fægri & van der Pijl, ; Saunders, ), pollination success is probably promoted by increasing the overall period available for floral visits.…”

Biologia floral, fenologia reprodutiva e polinização de Xylopia aromatica (Lam.) Mart. (Annonaceae) em uma área de Cerrado no oeste da Bahia

“…Isto costuma ser explicado pela ocorrência da protoginia nesta família, um mecanismo temporal responsável pela separação das fases masculina e feminina da flor, sem que haja qualquer sobreposição entre elas, e com a precedência da fase feminina, ou seja, quando há liberação do pólen, o estigma já não poderia mais recebê-lo (Endress, 2010;Paulino-Neto, 2015;Fachardo et al, 2015). No entanto, Gottsberger et al (2014) afirma que, em Annonaceae, no início da fase estaminada, os estigmas ainda estão levemente receptivos; haveria, portanto, um curto período de sobreposição entre a longa fase pistilada e a curta fase estaminada em que a autopolinização poderia ocorrer o que não foi registrado no presente estudo.…”

Técnicas de Cruzamentos de Psidium cattleyanum Sabine para Utilização em Programas de Melhoramento Genético

“…As espécies vegetais possuem a capacidade de geração de novos indivíduos por meio da reprodução sexuada, uma das principais formas dessa reprodução é por meio da polinização. A polinização ocorre de diversas maneiras, sendo por fatores bióticos, no caso, a transferência de gametas com auxílio de seres vivos (agentes polinizadores) ou por fatores abióticos, onde ocorre a troca de material genético entre plantas através de fatores ambientais, como vento (anemofilia) e água (hidrofilia) (GOTTSBERGER, 2014).…”