番荔枝科(Annonaceae)传粉室类型及其演化意义

花部结构与传粉者协同进化是有花植物成功演化的关键原因,在番荔枝科的植物中传粉室是一个非常明显的花部结构。由于该科花瓣的大小、轮数及每轮花瓣数、花瓣间的连合方式等高度多样,导致其传粉室形态也高度多样。番荔枝科107属中68属具详细的花部结构研究,该文根据开花期传粉室的闭合情况将这68属的传粉室分为开放型、半闭合型和闭合型3类,研究其系统演化意义。结果表明:(1) 24属具开放型传粉室,38属具半闭合型传粉室,26属具闭合型传粉室;约17属具2种或3种传粉室类型。(2)不同传粉室类型的植物与传粉者之间具有一定的对应关系,蜂类和蝇类主要为开放型传粉室或传粉室空间较大的半闭合型和闭合型传粉室植物传粉;蓟马主要为半闭合型与闭合型传粉室植物传粉。(3)古热带和新热带是番荔枝科植物的分布中心。分布于古热带的植物种数最多,但传粉室类型和传粉者较单一;分布于新热带的植物种数相对较少,但传粉室类型与传粉者都高度多样性。已有研究表明非洲是番荔枝科植物的起源地,开放型传粉室的植物主要分布于热带非洲,普遍存在于各族早期分化的属中,且均由小甲虫进行传粉,是该科较原始的传粉室类型;半闭合型分布于热带非洲、热带亚洲及热带美洲,闭合型传粉室主要分布于热带亚洲,这两类传粉室植物的传粉者也较多样性,是番荔枝科植物中较进化的传粉室类型。

Classification of pollination chamber and evolution significance of Annonaceae

Floral structure co-evolution with pollinators is a key factor of the success of evolution in flowering plants. In Annonaceae, pollination chamber is a characteristic feature of floral structure. Diversity of the flowers size, perianth whorls, the number of petals per whorl and the connecting pattern between petals, lead to annonaceous morphology of pollination chamber hightly diversity. The floral structures of 68 of total 107 genera in Annonaceae were reported to date. According to the closed degree of the pollination chamber during anthesis, pollination chambers of the 68 genera were classified into three types: open type, partially closed type and tightly closed type to research the evolution of pollination chambers in Annonaceae. The results were as follows:(1)24 genera existing the open type pollination chamber; 38 genera existing the partially closed type and 26 genera existing the tightly closed type. Approximately 17 genera contain two or three types of pollination chamber.(2)Different pollination chamber types had correspondent relationships with different pollinators. The bees and flies mainly pollinated for the species with open pollination chamber, as well as for the species that had partially closed and tightly closed chambers with larger space of chamber. The thrips mainly pollinated partially closed and tightly closed species.(3)Old-tropics and Neotropics were the distribution center of Anno-naceae. The species distributed in Old-tropics were very abundant but the types of chambers and pollinators were very unitary. The species distributed in Neotropics were fewer, but the types of chambers and pollinators were various. Previous studies have suggested that Africa is the origin center of Annonaceae. Open pollination chamber mainly distributed in African tropics, and commonly existed in earlier differentiate genera, which pollinated by small beetles. It was considered that open pollination chamber was the ancestral trait in Annonaceae; partially closed type distributed in African tropics, Asian tropics and American tropics; and tightly closed type mainly distributed in Asian tropics. Pollinators of the both had diversities. Therefore, the chambers of partially closed and tightly closed are more derived in Annonaceae.