DOI: 10.5061/dryad.p021fq5
title: Data from: Spatial variation in herbivory, climate and isolation predict plant height and fruit phenotype in Plectritis congesta island populations

description: Climate 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.
description: Skaien 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