Figure 1.
Eliza Spring, Zilker Park, Austin (Travis County), Texas and Transect Lines for Invertebrate Sampling.
The lower dam of Barton Springs Pool, which hosts another population of Eurycea sosorum, is visible in the distance. Arrow marks pipe where water exits Eliza Spring. Dashed lines indicate transects along which macroinvertebrate samples were taken.
Table 1.
Study-wide means ±1SD of stable isotope values and percent carbon and nitrogen for Eurycea sosorum and prey tissues.
Figure 2.
Mean ±1SE prey density and Eurycea sosorum density from Eliza Spring.
N = 9 invertebrate samples per sampling date. Higher SE reflects more patchy spatial distribution of prey between sampling points. Only results for the three invertebrate species that met the criteria outlined in Methods are shown.
Figure 3.
Stable isotope biplots of individual Eurycea sosorum and mean prey items.
2.31‰ is subtracted from each salamander δ15N‰ value to reflect isotopic discrimination. Prey stable isotope values are shown as study-wide means ±1SD.
Figure 4.
Mixing model estimated contributions of amphipods, planarians and chironomids to the diet of Eurycea sosorum.
Bayesian credible intervals show estimated contributions of each prey item to the diet of E. sosorum derived from the stable isotope mixing model SIAR. Relative abundance of prey uses same scale on Y-axis.
Figure 5.
Strauss’ linear electivity index for amphipods, planarians and chironomids in the diet of adult Eurycea sosorum.
Values near +1 indicate high selection despite low availability in the environment (strong electivity), values near zero indicate foraging in proportion to availability in the environment (no electivity), and values near −1 indicate that prey is not selected despite high availability in the environment (avoidance).