WEATHER_daily_2005_2009WEATHER_daily_2005_2009 contains summarized daily data from automated weather stations, processed with Hobo ware software (Onset Computer Corp., Bourne, MA, USA). Columns are as follows. | site_abbr = abbreviated site weather_id = site index no. | demography_id = index number of the site if it resided at a population where demographic data were collected | easting_UTM_NAD27 - easting in meters UTM NAD 1927, zone 11 North | northing_UTM_NAD27 - northing in meters UTM NAD 1927, zone 11 North | elevation - meters above sea level | date_time | year | month | Precip_mm – daily cumulative precipitation in mm | Tmax_C - daily maximum temperature, in degrees centigrade | Tmin_C – daily minimum temperature, in degrees centigrade | Tmean_C - daily mean temperature, in degrees centigradeWEATHER_seasonal_meansWEATHER_seasonal_means_2005-2009 contains data collected by automated weather stations and processed by Hoboware (Onset Computer Corporation, Bourne, MA, USA), summarized by segment of the growing season and by year, in columns as follows. Variables not described have names that should be self-explanatory. | site_abbr - abbreviated site name | weather_id = station index no. | demography_site_id - index no. if station resided at population where demographic data were collected | easting - in meters, UTM NAD 1927, zone 11 North | northing - in meters, UTM NAD 1927, zone 11 North | elevation - metera above sea level | NovJan2005_2009_Tmax | NovJan2005_2009_Tmin | NovJan2005_2009_Tmean | FebJun2006_2009_Tmax | FebJun2006_2009_Tmin | FebJun2006_2009_Tmean | FebOct_2006_2009_ Tmax | FebOct_2006_2009_Tmin | FebOct_2006_2009_Tmean| Nov2005Jan2006_precip | FebJun2006_precip | JulOct2006_precip | JanOct2006 precip | Nov2006Jan2007_precip | FebJun2007_precip | JulOct2007_precip | JanOct2007_precip | Nov2007Jan2008_precip | FebJun2008_precip | JulOct2008_precip | JanOct2008_precip | Nov2008Jan2009_precipDEMOGRAPHY_41pops_2006_2009The file called "DEMOGRAPHY_41pops_2006_2009" contains the following variables, based on repeated field observations. | Site = population name | demography_site_id – an index number for each population | Easting – eastward position (longitude) in meters, UTM NAD 27 zone 11 North | Northing – northward position (latitude) in meters, UTM NAD 27 zone 11 North | area(ha) – population area in hectares, as estimated in 2006 | Year - year | No_plots – number of 0.5 m-squared quadrats sampled for demography data | No fruiting plants – mean no. of plants that reached fruiting stage within quadrats | No fruits – total number of fruiting plants (1-4 per quadrat) that underlie the following per-plant estimates | mean no fruits per plant – self-explanatory | stdev fr per plant – standard deviation of the above | mean no seeds per fruit = average number of seeds per fruit in a sample of single fruits (from median positions on stems) from each of 30 individuals per population | stdev sds per fr = standard deviation of the above variable | mean fruiting plants per m2 = average density of fruiting plants per meter-squared | stdevfrplm2 = standard deviation of the above | mean total fruits per m2 = average number of fruits (on any number of plants) per meter-squared | stdevfrm2 = standard deviation of the above | mean total seeds per m2 = average number of fruits (on any number of plants) per meter-squared | stdevsdm2 = standard deviation of the above | No fruiting plants per site = estimated total population size of fruiting individuals | stdev fr pl per site = standard deviation of the above | total no fruits per site = estimate of the total number of fruits in each population | stdev no fr per site = standard deviation of the above | Total no seeds per site = estimate of the total number of fruits in each population | stdev no sds per site – standard deviation of the aboveDEMOGRAPHY_vital_rate_estimates_20pops_2005_2009The file "DEMOGRAPHY_vital_rate_estimates_20pops_2005_2009" contains the following variables, estimated from field observations and experiments, in columns as follows. | Population - abbreviated site name | demography_site_id = index no.| SiteArea(ha) - population area in ha; : s1(R1), CL_lo, CL_up, s1(R2), CL_lo, CL_up, s1(R3), CL_lo, CL_up, s2(R1), CL_lo, CL_up, s2(R2), CL_lo, CL_up, s2(R3), CL_lo, CL_up, s3(R1), CL_lo, CL_up, s3(R2), CL_lo, CL_up, s4(R1), CL_lo, CL_up, s4(R2), CL_lo, CL_up, s5(R1), CL_lo, CL_up, s6(R1), CL_lo, CL_up, g1(R1), CL_lo, CL_up, g1(R2), CL_lo, CL_up, g1(R3), CL_lo, CL_up, g2(R1), CL_lo, CL_up, g2(R2), CL_lo, CL_up, g3(R1), CL_lo, CL_up, sigma(06), CL_lo, CL_up, sigma(07), CL_lo, CL_up, sigma(08), CL_lo, CL_up, sigma(09), CL_lo, CL_up, F(06), SE, F(07), SE, F(08), SE, F(09), SE, phi(06), SE, phi(07), SE, phi(08), SE, phi(09), SE, MeanSeedlings(06), SE, MeanSeedlings(07), SE, MeanSeedlings(08), SE, MeanSeedlings(09), SE, MeanFruiting(06), SE, MeanFruiting(07), SE, MeanFruiting(08), SE, MeanFruiting(09), SE, SdlngO/E(07), SdlngO/E(08), Lambda_SSPECIES_LOCATIONS_forty_oneLocations of Clarkia xantiana ssp. xantiana populations. Easting is eastward position (longitude) in meters, UTM NAD 27 zone 11 North, and northing is northward position (latitude) in meters, UTM NAD 27 zone 11 North.SPECIES_LOCATIONS_lambda_1_or_greaterLocations of Clarkia xantiana ssp. xantiana populations confirmed to have long-term stochastic lambda estimates greater than 1.Easting is eastward position (longitude) in meters, UTM NAD 27 zone 11 North, and northing is northward position (latitude) in meters, UTM NAD 27 zone 11 North.GIS_Elevation_maskAscii file for species distribution modeling, locations in UTM NAD 1927, Zone 11 North, cellsize = 100 m. This file is a "mask" for excluding areas > 1500 m in elevation.GIS_Sampling_maskAscii file for species distribution modeling, locations in UTM NAD 1927, Zone 11 North, cellsize = 100 m. This file is a "mask" for excluding areas that were searched less thoroughly for natural populations.GIS_Slope_aspectAscii file for species distribution modeling, locations in UTM NAD 1927, Zone 11 North, cellsize = 100 m. This file contains slope aspect, in degrees, estimated from a re-scaled 30 m digital elevation model (USGS).GIS_Slope_inclinationAscii file for species distribution modeling, locations in UTM NAD 1927, Zone 11 North, cellsize = 100 m. This file contains slope inclination, in degrees, estimated from a re-scaled 30 m digital elevation model (USGS).GIS_Spring_Precip_CVAscii file for species distribution modeling, locations in UTM NAD 1927, Zone 11 North, cellsize = 100 m. This file contains estimates of the coefficient of variation of cumulative spring (Feb-June) precipitation for the period 2005-2009, using kriging to interpolate between weather stations.GIS_Spring_Precip_meanAscii file for species distribution modeling, locations in UTM NAD 1927, Zone 11 North, cellsize = 100 m. This file contains estimates of the mean of cumulative spring (Feb-June) precipitation for the period 2005-2009, using kriging to interpolate between weather stations.GIS_Spring_Temp_meanAscii file for species distribution modeling, locations in UTM NAD 1927, Zone 11 North, cellsize = 100 m. This file contains estimates of the mean of spring (Feb-June) temperature for the period 2005-2009, using regression of weather station values on elevation and estimated 21 March solar radiation.GIS_Surface_rockAscii file for species distribution modeling, locations in UTM NAD 1927, Zone 11 North, cellsize = 100 m. This file contains primary bedrock types from USGS surface geology records.GIS_Winter_Precip_CVAscii file for species distribution modeling, locations in UTM NAD 1927, Zone 11 North, cellsize = 100 m. This file contains estimates of the coefficient of variation of cumulative winter (Nov-Feb) precipitation for 2005-2009, interpolated between weather stations by kriging.GIS_Winter_Precip_meanAscii file for species distribution modeling, locations in UTM NAD 1927, Zone 11 North, cellsize = 100 m. This file contains estimates of the mean of cumulative winter (Nov-Feb) precipitation for the period 2005-2009, using kriging to interpolate between weather stations.SPECIES_LOCATIONS_twenty_demography_sitesLocations of Clarkia xantiana ssp. xantiana populations that were the subjects of detailed demographic sampling and experiments. Easting is eastward position (longitude) in meters, UTM NAD 27 zone 11 North, and northing is northward position (latitude) in meters, UTM NAD 27 zone 11 North.

Potential causes of species’ geographic distribution limits fall into two broad classes: (1) limited adaptation across spatially variable environments and (2) limited opportunities to colonize unoccupied areas. Combining demographic studies, analyses of demographic responses to environmental variation, and species distribution models, we investigated the causes of range limits in a model system, the eastern border of the California annual plant Clarkia xantiana ssp. xantiana. Vital rates of 20 populations varied with growing season temperature and precipitation: fruit number and overwinter survival of 1-year-old seeds declined steeply, while current-year seed germination increased modestly along west-to-east gradients in decreasing temperature, decreasing mean precipitation, and increasing variation in precipitation. Long-term stochastic finite rate of increase, ls, exhibited a fourfold range and varied among geologic surface materials as well as with temperature and precipitation. Growth rate declined significantly toward the eastern border, falling below 1 in three of the five easternmost populations. Distribution models employing demographically important environmental variables predicted low habitat favorability beyond the eastern border. Models that filtered or weighted population presences by ls predicted steeper eastward declines in favorability and assigned greater roles in setting the distribution to among-year variation in precipitation and to geologic surface material. These analyses reveal a species border likely set by limited adaptation to declining environmental quality.