Weller Stephen G, Sakai Ann K, Campbell Diane R, Powers John M, Peña Sean R, Keir Matthew J, Loomis Alexander K, Heintzman Scott M, Weisenberger Lauren
Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, 92697, USA.
O'ahu Army Natural Resources Program, Pacific Cooperative Studies Unit, University of Hawai'i, Honolulu, HI 96822, USA.
New Phytol. 2017 Feb;213(3):1533-1542. doi: 10.1111/nph.14254. Epub 2016 Nov 7.
Shifts in pollination may drive adaptive diversification of reproductive systems within plant lineages. The monophyletic genus Schiedea is a Hawaiian lineage of 32 extant species, with spectacular diversity in reproductive systems. Biotic pollination is the presumed ancestral condition, but this key element of the life history and its role in shaping reproductive systems has remained undocumented. We observed floral visitors to two species of Schiedea and conducted field experiments to test pollinator effectiveness. We used choice tests to compare attraction of pollinators to species hypothesized to be biotically vs wind-pollinated. Pseudoschrankia brevipalpis (Erebidae), a recently described moth species known only from O'ahu, visited hermaphroditic Schiedea kaalae and S. hookeri and removed nectar from their unique tubular nectary extensions. Pseudoschrankia brevipalpis effectively pollinates S. kaalae; single visits to emasculated flowers resulted in pollen transfer. In choice tests, P. brevipalpis strongly preferred these hermaphroditic species over two subdioecious species capable of wind pollination. A shift from biotic to abiotic pollination is clearly implicated in the diversification of reproductive systems within Schiedea. Abundant pollination by a previously unknown native moth in experimental and restored populations suggests the potential for restoration to re-establish native plant-pollinator interactions critical for production of outcrossed individuals with high fitness.
传粉方式的转变可能推动植物谱系内繁殖系统的适应性多样化。单系属Schiedea是夏威夷的一个谱系，现存32个物种，其繁殖系统具有惊人的多样性。生物传粉被认为是祖先状态，但这种生命史的关键要素及其在塑造繁殖系统中的作用仍未得到证实。我们观察了两种Schiedea的访花者，并进行了田间实验以测试传粉者的有效性。我们使用选择试验来比较传粉者对假设为生物传粉与风媒传粉物种的吸引力。短须伪尺蛾（夜蛾科）是一种最近描述的蛾类物种，仅在瓦胡岛发现，它访两性花的卡阿莱Schiedea和胡克氏Schiedea，并从其独特的管状蜜腺延伸部分采集花蜜。短须伪尺蛾有效地为卡阿莱Schiedea传粉；单次访问去雄花导致了花粉转移。在选择试验中，短须伪尺蛾强烈偏好这些两性花物种，而不是两种能够风媒传粉的亚雌雄异株物种。传粉方式从生物传粉向非生物传粉的转变显然与Schiedea属内繁殖系统的多样化有关。在实验种群和恢复种群中，一种先前未知的本地蛾类进行的大量传粉表明，恢复过程有可能重新建立对产生具有高适合度的异交个体至关重要的本地植物 - 传粉者相互作用。
