Figure 1.
Enrichment over time from a pool of water.
The original pool of water falls along the global meteoric water line (GMWL), the line representing isotope ratios of all precipitation globally. This pool then enriches in heavy isotopes over time because of higher evaporation of lighter isotopes. The rate of evaporation is influences by temperature and humidity, as is the slope of the line.
Table 1.
Dates when each combination of temperature and humidity were tested for the two-source experiment on field crickets in 2009.
Figure 2.
The isotope ratios of the three runs from the single-source temperature alteration experiment.
All three runs experienced similar experimental conditions, with relatively high, but variable humidity (Table S2). These lines display strong and statistically significant correlations (Table 2). There are no statistical differences between the estimates of the water sources and the estimates of each run (Table 3). While there is an overall difference in slope and intercepts between all lines from the single-source experiments (Table 4), there are no statistically significant differences between any two lines (Table 5). Note: not all details are visible (e.g. the lower prediction limit for the 35°C crickets is hidden by the fitted line for the 25°C crickets).
Figure 3.
The isotope ratios of runs at 25°C from the single-source experiments.
These two runs differ in humidity and experimental set-up, but not temperature. The temperature alteration experiment had relatively high, but variable humidity, whereas the controlled low humidity experiment had low and constant humidity (Table S2). These lines display strong and statistically significant correlations (Table 2). There are no statistical differences between the estimates of the water sources and the estimates of each run (Table 3). While there is an overall difference in slope and intercepts of all lines from the single-source experiments (Table 4), there are no statistically significant differences between these two lines (Table 5).
Table 2.
Regression statistics for each run from the single-source experiments.
Table 3.
Comparison of the fitted values and upper and lower prediction levels of the δ2H of the cricket regression line with the values of the water source at the mean values and upper and lower confidence levels of δ18O of the source (CL = confidence limit, PL = prediction limit).
Table 4.
ANCOVA tables testing for differences in slopes and intercepts between regression lines through isotopic ratios of each run in both the single-source experiments combined.
Table 5.
Post-hoc Tukey's HSD comparisons of differences between regression lines in each run, following ANCOVA (see Table 4).
Figure 4.
Hydration of crickets collected at each time in the single-source temperature alteration experiment.
There is no significant correlation between time since water removal and hydration.
Table 6.
MANOVA table testing for differences in the isotope ratios of animals across collection times, including results from all 3 experiments.
Figure 5.
Example determinations of the mean contribution of de-ionized water to body water with two sources.
Panel A shows field crickets (G. alogus) and panel B shows wolf spiders (H. antelucana), both at 25°C and 6 g/m3 humidity, from the two-source experiment. See Table 7 for mixing model calculations of the percentage contribution of each water source.
Table 7.
Population mean percentage of body water obtained from the depleted water source in the two-source experiment, and lower and upper estimates of the range for individual crickets, from mixing models based on mean values of sources and intersection points between source regression lines and animal regression lines.