Low outcrossing rates and shift in pollinators in New Zealand pohutukawa (Metrosideros excelsa; Myrtaceae).
Low outcrossing rates and shift in pollinators in New Zealand pohutukawa (Metrosideros excelsa; Myrtaceae).
复制标题
DOI：
10.2307/2656719
复制
发表时间：
2000-09
影响因子：
3
通讯作者：
Gabriele Schmidt‐Adam;A. Young;B. Murray
中科院分区：
文献类型：
--
作者：
Gabriele Schmidt‐Adam;A. Young;B. Murray
新西兰pohutukawa (Metrosideros excelsa)，桃金娘科的一员，是新西兰北部海岸线特有的一种大型，大量开花的树木。大陆种群已经减少到支离破碎的林分，原始的鸟类传粉者已经在很大程度上被引进的物种所取代。在几个近海岛屿上的本地传粉者动物群基本上是完整的，包括三种新西兰采蜜者（蜜蜂科）和本地独居蜜蜂。我们估计了三个大陆种群和两个岛屿种群的多位点异交率，发现它们是桃科中最低的种群（t(m) = 0.22-0.53）。传粉者的转移对交配系统没有可测量的影响。大量开花有利于雌雄同体的自交，在生长6个月时可检测到近交对幼苗高度的抑制。F(s) [Wright（1965）固定指数]在所有种群中始终高于F(m)，表明选择可能在种群达到生殖成熟之前消除自交后代。结果表明，大陆种群中由于传粉者的变化而增加的自交并不是导致该物种目前再生能力差的原因。
New Zealand pohutukawa (Metrosideros excelsa), a member of the Myrtaceae, is a large, mass-flowering tree endemic to northern New Zealand coastlines. Mainland populations have been reduced to fragmented stands, and the original suite of bird pollinators has been largely replaced by introduced species. The native pollinator fauna on several offshore islands is largely intact and includes three species of the New Zealand honeyeaters (Meliphagidae) and native, solitary bees. We estimated multilocus outcrossing rates for three mainland and two island populations and found that they were among the lowest in the Myrtaceae (t(m) = 0.22-0.53). The shift in pollinators had no measurable effect on the mating system. Mass-flowering facilitates geitonogamous selfing, and inbreeding depression in seedling height was detectable at 6 mo of growth. F(s) [Wright's (1965) Fixation Index] was consistently higher than F(m) in all populations, indicating that selection may eliminate selfed offspring from populations prior to achieving reproductive maturity. Results suggest that increased selfing in mainland populations due to pollinator changes is not responsible for current patterns of poor regeneration of this species.