Morphological aspects and phylogenetic analyses of pollination systems in the Tylophora-Vincetoxicum complex (Apocynaceae-Asclepiadoideae) in Japan

Abstract

Pollinators of two Cynanchum, five Tylophora, and 16 Vincetoxicum species were observed in 26 populations in Japan. The following pollination systems were observed in 18 species: moth pollination, generalized insect pollination, wasp pollination, dipteran pollination, both dipteran and moth pollination, and autogamy. Principal component analysis based on 13 floral characters indicated that the size of the pollinator tended to increase with sizes of all characters measured. Furthermore, species that have developed interstaminal parts of the corona and concealed stigmatic chambers tend to be pollinated by long-tongued insects. The phylogenetic distribution of pollinator types showed that species belonging to Clade I are pollinated exclusively by Diptera, whereas those of Clade II are pollinated by four insect orders. The most prominent pollinator transition in the TylophoraVincetoxicum complex is dipteran to moth pollination. The most common morphological change of the plants from dipteran pollination to moth pollination, or vice versa, is modification of the corolla. In the Tylophora-Vincetoxicum complex, pollination mode shifts are generally accompanied by modifications of the corona and the structure of gynostegium. One hypothesis for the rapid radiation observed in Clade II is that a widely distributed species may have partitioned its distribution in the relatively near past and adapted to various environments, in which the dominant pollinators were different, and that the local races may then have diverged from each other after they were isolated.

VincetoxicumandTylophora(Apocynaceae: Asclepiadoideae: Asclepiadeae)—two sides of the same medal: Independent shifts from tropical to temperate habitats

“…As noted earlier (Yamashiro & al., 2004a), the taxa of clade E show very little genetic diversity in all regions studied. On the other hand, Yamashiro & al. (2008) showed that floral characters in this clade are highly diverse, as are the pollination systems.…”

“…The four European species (V. creticum, V. hirundinaria, V. nigrum, V. rossicum) form a very well supported subclade (F321) in sister-group position to an also well-supported subclade comprising four erect species of temperate Asia (F322). Yamashiro & al. (2008) noted that the flowers in their clade I, which corresponds to clade F32 of the present analysis, comprises many taxa not producing nectar and having small and inconspicuous flowers.…”

“…They found that East Asian Vincetoxicum falls into two clades with different degrees of interclade genetic diversification. Based on this work, they studied morphological characters and pollination systems in these two clades (Yamashiro & al., 2008), concluding that the two clades differ in pollination systems, with their clade I being exclusively Diptera-pollinated while members of their clade II are pollinated by various insects. Polyploidisation was considered to play only a minor role in the differentiation of the two clades (Yamashiro & al., 2008), and adaptation to different habitats followed by isolation, and, in the case of clade II, adaptation to different pollinators were considered the main causes of diversification.…”

“…The present paper aims to continue where Yamashiro & al. (2004aYamashiro & al. ( , 2008 stopped, and include the African members of the subtribe in the analysis enlarged by more molecular markers.…”

Evolução da morfologia floral e estrutura de comunidades em um clado de Lianas Tropicais (Bignonieae, Bignoniaceae)

“…Specifi cally, a better understanding of the order of evolution and the lability of individual traits and of the patterns of correlated evolution among those traits could greatly enhance our understanding of the processes that may have led to current variation in fl oral morphologies ( P é rez et al, 2006 ). Some studies have addressed the patterns of evolution of individual fl oral traits that are associated with attractiveness to animals (reviewed by Fenster et al, 2004 ; with subsequent studies by Ackermann and Weigend, 2006 ;P é rez et al, 2006, Whittall and Hodges, 2007Okuyama et al, 2008 ;Smith et al, 2008 ;Tripp and Manos, 2008 ;Yamashiro et al, 2008 ). However, no study has ever evaluated the exact order of evolution of individual traits in a temporal context.…”