Data from: Spatial variation in herbivory, climate and isolation predict plant height and fruit phenotype in Plectritis congesta island populations

AbstractClimate and herbivory can each drive natural selection on plant traits, but may interact to give rise to different patterns in trait distributions when surveyed across island populations. These different patterns may arise because the occurrence of ungulate herbivores often varies across archipelagos, potentially leading to strong and abrupt spatial heterogeneity in the direction or intensity of natural selection. In contrast, climate tends to vary gradually and thus is more likely to lead to gradual clines in trait values. Population isolation may also affect trait values, given that random genetic drift may fix alleles or traits in the absence of gene flow, or because gene flow between populations with similar or opposing selection pressures may augment or swamp the effects of selection. Here, we estimate the independent and interactive effects of deer, climate and isolation on fruit phenotype and plant height in 285 Plectritis congesta populations at 77 island and 44 mainland sites in western North America. Plectritis congesta is a palatable winter annual with two fruit phenotypes based on a simple Mendelian locus with clear dominance, and heritable variation in height as a polygenic trait. Fruit phenotype and plant height were well-predicted by deer occurrence; plants in populations with resident deer were short (15.0 ± 1.1 cm) and mainly expressed wingless fruits (73.0 ± 4.0 %), whereas plants in populations without deer were 2.6 times taller (38.9 ± 5.3 cm) and only 9.0 ± 1.6 % expressed wingless fruits. Wingless fruits were less common in populations experiencing wetter conditions with more seasonal variability in temperatures, particularly in the absence of deer. In contrast, population isolation was unrelated to fruit phenotype, except in populations rarely exposed to deer, where plants expressed phenotypes more like those in populations without deer as isolation increased. Our results are consistent with the hypothesis that spatial variation in browsing by deer, or other factors correlated with it, contributes to population-level variation in fruit phenotype and plant height in P. congesta, and that climate leads to a modest spatial gradient in plant height., Usage notesSkaien and Arcese_P. congesta geographic data_Journal EcologyTab 1 (“Geographic Survey Fruit Frequency”): Data were collected throughout the Georgia Basin from 2005 to 2014 (“Year”) from April to June of each year. Populations that were surveyed more than once were assessed for changes over time, and only the most recent measurement was included in the data set. The study species is seablush, Plectritis congesta. “Area” and “Location” together represent each population. “Isl.Main” represents whether a population was on an island or the mainland (with Vancouver Island considered as part of the mainland). “Deer” represents whether the island had deer present, absent or rarely hosted deer. UTM coordinates are represented by “N” for Northing and “E” for Easting. The number of wingless fruits in each set of 100 (“value”; from counts of 20 individuals in 5 different areas of the population) is represented by “sum.ww”. Together, “value” and “sum.ww” create the proportion of plants bearing wingless fruits (“Freq.of.ww”). “PC1” and “PC2” represent the values from the Principal Components Analysis (PCA) for climatic variables (see Appendix). The amount of land in a 1 km buffer (“1km_Area_Land”) was transformed into a percentage (“1km_Percent_Land”). From this, we also have the percentage of land area that is water in a 1 km radius of the center of the surveyed population (“1km_Percent_Water”). Tab 2 (“1 m belt transects”): Data were collected from May to June 2014. “Location” represents the population sampled, accompanied by UTM GPS coordinates (“N” for Northing and “E” for Easting). The average measured heights of 20-40 plants along each transect is represented by “avheight”, with the standard deviation of height represented by “stdevheight”. The average depth of 5 measurements at 20 cm intervals along the 1 m belt transect is represented by “avdepth”, and the standard deviation in depth is represented by “stdevdepth”. The “Freq.of.ww” represents the proportion of fruits that were wingless from the total count of 100 (“value”). “PC1” represents values from the Principal Components Analysis (PCA) for climatic variables (see Appendix). “1km_Percent_Water” represents the percentage of land cover that was water in a 1 km radius of the center of the surveyed population.Skaien_P. congesta geographic data_Journal Ecology.xlsx

**摘要** 气候与植食作用均可对植物性状驱动自然选择，但在跨岛屿种群开展调查时，二者可能产生交互作用，进而塑造性状分布的不同模式。此类差异模式的产生，缘于有蹄类植食动物（ungulate herbivores）的分布情况通常在群岛间存在差异，可能导致自然选择的方向或强度出现强烈且突变的空间异质性。与之相对，气候的变化往往较为平缓，因此更易引发性状值的渐变梯度（cline）。种群隔离同样可能影响性状值：一方面，随机遗传漂变（genetic drift）可在无基因流的情况下固定等位基因（alleles）或性状；另一方面，携带相似或相反选择压力的种群间的基因流，可能增强或淹没选择的效应。

本研究针对北美西部77个岛屿位点与44个大陆位点的285个距花缨草（*Plectritis congesta*）种群，评估了鹿类、气候与隔离对其果实性状与株高的独立及交互影响。距花缨草是一种可被取食的冬季一年生植物，其果实存在两种由单孟德尔位点（Mendelian locus）控制的简单显性遗传性状，且株高作为多基因性状存在可遗传变异。

鹿类的存在可较好地预测果实性状与株高：存在定居鹿类的种群中，植株株高为15.0 ± 1.1 cm，且主要表现为无翅果实（占比73.0 ± 4.0%）；而无鹿类的种群中，植株高度是前者的2.6倍（38.9 ± 5.3 cm），无翅果实占比仅为9.0 ± 1.6%。无翅果实的占比在湿度更高、温度季节变异性更强的种群中更低，尤其在无鹿类的种群中这一趋势更为显著。与之相对，种群隔离与果实性状并无关联，仅在极少暴露于鹿类的种群中，随着隔离程度升高，植株的果实性状更趋近于无鹿类种群的表现。

本研究结果支持以下假说：鹿类取食的空间变异，或与之相关的其他因素，可导致距花缨草种群间果实性状与株高的变异；而气候则会使株高呈现出温和的空间梯度。

**使用说明**
《Skaien与Arcese_距花缨草地理数据_Journal Ecology》表1（"地理调查果实频率"）：数据于2005年至2014年间在乔治亚盆地（Georgia Basin）采集，每年采样时段为4月至6月。对于多次调查的种群，我们评估了其随时间的变化，仅将最新一次的测量结果纳入数据集。研究物种为海蒲草（seablush），即距花缨草（*Plectritis congesta*）。

"Area"与"Location"共同标识每个种群。"Isl.Main"用于标识种群是否位于岛屿或大陆（温哥华岛被视为大陆的一部分）。"Deer"用于标识该岛屿是否存在鹿类、无鹿类，或仅极少有鹿类活动。UTM坐标以"N"代表北距（Northing）、"E"代表东距（Easting）。每100个果实中无翅果实的数量（"value"；数据来自种群5个不同区域内20个个体的计数）记为"sum.ww"。"value"与"sum.ww"共同计算得到无翅果实植株占比（"Freq.of.ww"）。"PC1"与"PC2"代表气候变量主成分分析（Principal Components Analysis, PCA）得到的分值（详见附录）。对1 km缓冲区内的陆地面积（"1km_Area_Land"）进行百分比转换，得到"1km_Percent_Land"。由此，我们还可得到调查种群中心1 km半径范围内的陆地水域占比（"1km_Percent_Water"）。

表2（"1米样带"）：数据于2014年5月至6月采集。"Location"标识采样种群，附带UTM GPS坐标（"N"为北距，"E"为东距）。沿每条样带测得的20~40株植株的平均高度记为"avheight"，株高标准差记为"stdevheight"。沿1米样带以20 cm间隔获取的5次深度测量的平均值记为"avdepth"，深度标准差记为"stdevdepth"。"Freq.of.ww"代表总计数100个果实中无翅果实的占比（"value"）。"PC1"代表气候变量主成分分析（PCA）得到的分值（详见附录）。"1km_Percent_Water"代表调查种群中心1 km半径范围内的水域陆地覆盖占比。

文件：Skaien_距花缨草地理数据_Journal Ecology.xlsx