Data from: Pollinator-mediated reproductive isolation among dioecious fig species (Ficus, Moraceae)

The extent of isolation among closely related sympatric plant species
engaged in obligate pollination mutualisms depends on the fitness
consequences of interspecies floral visitation. In figs (Ficus),
interspecific gene flow may occur when pollinating wasps (Agaonidae) visit
species other than their natal fig species. We studied reproductive
isolation in a clade of six sympatric dioecious fig species in New Guinea.
Microsatellite genotyping and Bayesian clustering analysis of the fig
community indicated strong reproductive barriers among sympatric species.
One to two percent of fig populations consisted of hybrid individuals. A
new experimental method of manipulating fig wasps investigated the
reproductive consequences of conspecific and heterospecific pollinator
visitation for both mutualists. Fig wasps introduced to Ficus hispidioides
pollinated and oviposited in receptive figs. Seed development and seedling
growth were largely comparable between conspecific and heterospecific
crosses. Heterospecific pollinator fitness, however, was significantly
less than that of conspecific pollinators. Heterospecific pollinators
induced gall formation but offspring did not develop to maturity in the
new host. Selection on pollinators maintaining host specificity appears to
be an important mechanism of contemporary reproductive isolation among
these taxa that could potentially influence their diversification.

参与专性传粉互利共生的近缘同域植物类群之间的隔离程度，取决于跨物种访花所带来的适合度后果。在榕属（Ficus）植物中，当传粉榕小蜂（榕小蜂科，Agaonidae）造访其原生寄主之外的榕树种时，可能发生种间基因流。本研究针对新几内亚地区一个包含6种同域分布雌雄异株榕属植物的演化支，开展了生殖隔离相关研究。对该榕属群落开展的微卫星基因分型与贝叶斯聚类分析结果显示，同域分布的榕树种间存在较强的生殖隔离屏障；1%至2%的榕种群中存在杂交个体。本研究开发了一种全新的榕小蜂操控实验方法，用以探究同种与异种传粉者访花对互利共生双方的生殖后果。将榕小蜂引入粗毛榕（Ficus hispidioides）后，它们可在处于受粉敏感期的榕果内完成传粉与产卵行为。同种授粉与异种授粉两组实验的种子发育与幼苗生长情况整体相近，但异种传粉者的适合度显著低于同种传粉者。异种传粉者虽可诱导寄主形成虫瘿，但其后代无法在新寄主榕果中发育至成熟。维持传粉者寄主专一性的选择压力，似乎是这些类群间当代生殖隔离的重要机制，或可对其物种分化进程产生潜在影响。