科研之友
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摘要
Rafflesia species are endo-holoparasites of Tetrastigma (Vitaceae) vines. Despite receiving considerable attention because of their rarity, enormous flowers, and fascinating parasitic life style, surprisingly little is known about their host specificity and host preference. This lack of information prevents a better understanding of the evolution of the host-parasite associations and host-focused conservation management of these threatened plants. This study is the first comprehensive analysis of host specificity and preference in Rafflesia. A total of 180 host plants of 11 out of 13 species of Philippine Rafflesia as well as non-parasitized Tetrastigma plants from most areas where Rafflesia species have been found were included in our study. Morphological data and nuclear and plastid DNA sequence phylogenies were used to identify and distinguish Tetrastigma lineages. Our studies provide support for previous claims that Tetrastigma species are the exclusive hosts of Rafflesia. A total of eight lineages of Philippine Tetrastigma were identified of which six are hosts of Rafflesia. Most of these Tetrastigma lineages are hosts of multiple Rafflesia species. In addition, four Rafflesia species parasitize multiple Tetrastigma lineages. The finding that Tetrastigma lineages and Rafflesia species that are relatively common are involved in multiple host-parasite associations suggests that these Rafflesia species are less host-specific than previous studies indicated. However, because some sympatric Tetrastigma species are not among the observed host species, we tentatively conclude that Philippine Rafflesia show at least some degree of host specificity. Host phylogenies suggest that cospeciation might not have occurred in the diversification of Philippine Rafflesia and Tetrastigma.
- 出版日期2016-8
