Northwestern University, Program in Plant Biology and Conservation, Evanston, IL, 60201, USA.
Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60022, USA.
Am J Bot. 2023 Jun;110(6):e16156. doi: 10.1002/ajb2.16156. Epub 2023 Apr 23.
Animal pollinators play an important role in pollen dispersal. Here, we assessed differences in pollen and seed dispersal and the role of pollinator functional groups with different foraging behaviors in generating patterns of genetic diversity over similar geographic ranges for two closely related taxa. We focused on two members of Oenothera section Calylophus (Onagraceae) that co-occur on gypsum outcrops throughout the northern Chihuahuan Desert but differ in floral phenotype and primary pollinator: Oenothera gayleana (bee) and O. hartwegii subsp. filifolia (hawkmoth).
We measured breeding system and floral traits and studied gene flow and population differentiation at the local (<13 km; four populations) and landscape (60-440 km; five populations) scales using 10-11 nuclear (pollen dispersal) and three plastid (seed dispersal) microsatellite markers.
Both taxa were self-incompatible and floral traits were consistent with expectations for different pollinators. Seed and pollen dispersal patterns were distinctly different for both species. We found no evidence of genetic structure at the local scale but did at the landscape scale; O. gayleana showed greater differentiation and significant isolation by distance than in O. hartwegii subsp. filifolia. The plastid data were consistent with gravity dispersal of seeds and suggest that pollen dispersal is the principal driver of genetic structure in both species.
We demonstrated that pollinator functional groups can impact genetic differentiation in different and predictable ways. Hawkmoths, with larger foraging distances, can maintain gene flow across greater spatial scales than bees.
动物传粉媒介在花粉传播中起着重要作用。在这里，我们评估了具有不同觅食行为的传粉者功能群在相似地理范围内对花粉和种子扩散以及遗传多样性模式的作用，这些功能群在北奇瓦瓦沙漠北部的石膏露头区共同存在，但在花表型和主要传粉者上有所不同：Oenothera section Calylophus（Onagraceae）的两个成员Oenothera gayleana（蜜蜂）和 O. hartwegii subsp. filifolia（天蛾）。
我们测量了繁殖系统和花部性状，并使用 10-11 个核（花粉扩散）和 3 个质体（种子扩散）微卫星标记，在当地（<13 km；四个种群）和景观（60-440 km；五个种群）尺度上研究了基因流动和种群分化。
这两个分类群都是自交不亲和的，花部性状与不同传粉者的预期一致。两种物种的种子和花粉扩散模式明显不同。我们在当地尺度上没有发现遗传结构的证据，但在景观尺度上发现了；O. gayleana 比 O. hartwegii subsp. filifolia 表现出更大的分化和显著的距离隔离。质体数据与种子的重力扩散一致，并表明花粉扩散是两种物种遗传结构的主要驱动因素。
我们证明了传粉者功能群可以以不同且可预测的方式影响遗传分化。觅食距离较大的天蛾可以在更大的空间尺度上维持基因流动，而蜜蜂则不能。
