Breeding System And Pollination Biology Of Three Species Of Aquilegia (Ranunculaceae)

In angiosperm, floral traits vary a lot among species. The diversity and the evolution of different floral organs attract a lot of attention and remain one of the most important questions in evolutionary biology. Here we selected three kinds of Ranunculaceae plants, Aquilegia ecalcarata, Semiaquilegia adoxoides and Urophysa rockii to study their reproductive system and to analyze the adaptive relationship of floral and their pollinators. We adopted the common methods widely used in based on pollination biology and reproductive biology in attempt to find out the role of pollinators in the evolution of floral traits, especially the petal traits. The results are as follows:1) The breeding system of U. rockii is outcrossing with partial self-compatibility, in need of pollinators. We found out the the pollinators of U. rockii were Apis cerana and Platychirus sp.. A. cerana is nectar-sucking pollinator, thus the shout spur of U. cockii might adapt to this behavior of A. cerana. Furthermore, we also found out the petals of tribe Isopyreae plants mainly adapted adapt to the mouthparts of the pollinators, and the adaptation occurrede mostly between the petal traits and the pollinator with higher pollination efficiency when different kinds of pollinators visit the flowers.2) S. adoxoides relies predominantly on self-fertility in natural conditions, which might provide reproductive assurance when pollinators are scarce in early spring. According to our observations, the pollinator of S. adoxoides is Melittidae sp., which visit S. adoxoides for nactar. However, Melittidae sp. visit S. adoxoides at an extremely low frequency.3) A. ecalcarata is outcrossing species. The anther and stigma of A. ecalcarata always keep apart when in blossom. The movement of the androecium and gynoecium, may avoid self-pollination, which relies more on pollinators. We found out that the pollinators of A. ecalcarata are Tephritidae sp. and Platychirus sp.. They both visited A. ecalcarata for pollens only. The floral traits of spurless(or with a short one) and nectar free might result from the absence of nectar-sucking pollinators. Thus we inferred that nectar-sucking pollinators might palyed an important role in the evolution of petal in tribe Isopyreae. 4) In conclusion, we deduced that pollinator shift might be the main factor which drove the petal evolution in tribe Isopyreae.