Louis Calder Center - Biological Field Station, Fordham University, 31 Whippoorwill Road, Armonk, New York, 10504, USA.
Center for Urban Ecology, Fordham University, 441 East Fordham Road, Bronx, New York, 10458, USA.
Am J Bot. 2020 Nov;107(11):1504-1517. doi: 10.1002/ajb2.1554. Epub 2020 Oct 27.
Pollen dispersal, the main component of overall plant gene flow, generally decreases with increasing distance from the pollen source, but the pattern of this relationship may differ among sites. Although site-based differences in pollen dispersal may lead to over- or underestimation of gene flow, no studies have investigated pollen dispersal patterns among differing urban site types, despite the incongruent range of habitats in urban areas.
We used paternity assignment to assess pollen dispersal patterns in a wind-pollinated species (waterhemp; Amaranthus tuberculatus) and in an insect-pollinated species (tomato; Solanum lycopersicum) in experimental arrays at four disparate sites (two roof-level sites, two ground-level sites) in the New York (New York, USA) metropolitan area.
The number of seeds or fruits, a proxy for the number of flowers pollinated, decreased with increasing distance from the pollen donors at all sites for both species. However, the mean number of Amaranthus tuberculatusseeds produced at a given distance differed two-fold among sites, while the slope of the relationship between Solanum lycopersicumfruit production and distance differed by a factor of four among sites.
Pollen dispersal patterns may differ substantially among sites, both in the amount of pollen dispersed at a given distance and in the proportional decrease in pollen dispersal with increasing distance, and these effects may act independently. Accordingly, the capacity of plant species to adapt to climate change and other selection pressures may be different from predictions based on pollen dispersal patterns at a single location.
花粉散布是植物基因流的主要组成部分，通常随离花粉源距离的增加而减少，但这种关系的模式可能因地点而异。尽管基于地点的花粉散布差异可能导致对基因流的高估或低估，但没有研究调查过不同城市地点类型之间的花粉散布模式，尽管城市地区的栖息地范围不一致。
我们使用亲子关系分配来评估在四个不同地点（两个屋顶水平地点，两个地面水平地点）的实验排列中，风授粉物种（水稗；Amaranthus tuberculatus）和虫媒授粉物种（番茄；Solanum lycopersicum）的花粉散布模式。在纽约（美国纽约州）大都市区。
对于两种物种，所有地点的种子或果实数量（授粉花朵数量的代表）随离花粉供体距离的增加而减少。然而，在给定距离处产生的 Amaranthus tuberculatus 种子数量在地点之间差异两倍，而 Solanum lycopersicum 果实产量与距离之间的关系斜率在地点之间差异四倍。
花粉散布模式在不同地点之间可能有很大差异，包括在给定距离处散布的花粉量以及花粉散布随距离增加的比例减少，这些影响可能是独立的。因此，植物物种适应气候变化和其他选择压力的能力可能与基于单一地点花粉散布模式的预测不同。
