Figure 1.
Photographs of the study organisms.
Webs of Anelosimus jabaquara (A, scale bar 10 cm), A. baeza (B), A. studiosus (C), A. nigrescens (D), and A. dubiosus (E, B–E scale bar 5 cm). Also shown are male and female of A. nigrescens (F), female of A. baeza (G), and female of A. jabaquara (H, F-H scale bar 2.5 cm).
Table 1.
A description of the variables measured in Serra do Japi.
Figure 2.
The phylogenetic relationship, nest size, and distance from forest edge are shown for the five focal species.
The bold lines in the phylogeny diagram (a) represent highly social spider species (phylogeny redrawn from [33]). The five species that we observed in Serra do Japi, which were used in our analyses, are labeled in this figure. Other species are shown to demonstrate the phylogenetic distances between focal species. These species differ in the median nest size by an order of magnitude, with more social species building larger nests (b). The more social species tend to occur further from the forest edge than the subsocial and nearly solitary species (c) The boxplots show the median and the upper and lower quartiles. The whiskers encompass the 1.5x the interquartile range, and circles represent outliers. Letters show statistically significant differences between species (Dunnett-Tukey-Kramer test for b, posthoc test on Kruskal-Wallis for c).
Table 2.
Associations between all variables used in the principal components analysis.1
Figure 3.
Three of the five species investigated show significant differences in their mean position along three principal component axes.
The 95% confidence intervals for each species show moderate overlap between Anelosimus studiosus with A. baeza and A. nigrescens, but this may be due to the small sample size of A. studiosus. The social and intermediate social species (A. dubiosus and A. jabaquara) segregate from the subsocial and nearly solitary species (A. studiosus, A. baeza and A. nigrescens) along the first PC axis, which correlates with the distance from the forest edge (more negative values indicate that nests occur further inside the forest). Along the second PC axis, A. dubiosus differs from the other four species; more positive values indicate nests that are closer to the ground and built on the core of the plant. The three subsocial and nearly solitary species differ along the third PC axis, which reflects the local nest position and instar. The star represents the point where the confidence intervals measuring the position of Anelosimus jabaquara intercepts the y and z axis.
Table 3.
Principal components analysis results, indicating the weight of each variable on each PC axis as well as the eigenvalue and % of the variance accounted for by each axis.
Figure 4.
We compare local scale spatial variables, including nest height above ground, vegetation substrate diameter at breast height, and nest location on substrate.
Comparisons of forest edge species (left panel) and forest interior species (right panel) show that species in both habitats show some differences in nest position. Significant differences between comparisons are shown with different letters.
Figure 5.
The bars show the most common instar present in each of the observed nests.
Significant pairwise differences in age structure (Holm-Bonferroni corrected Chi-squared tests, with juveniles comprising a single category) are shown with letters to the right of each species diagram for the subsocial species. A previous long-term study found Anelosimus jabaquara and A. dubiosus to be offset by one month in their phenology [31], so we show the age structure of these species here for comparative purposes.