Figure 1 in Clues supporting photoperiod as the main determinant of seasonal variation in amphibian activity

Figure 1. Path diagram of structural equation model, evaluating 265 the hypotheses that anuran species respond to the month as a latent variable that is a construct of photoperiod, temperature and rainfall. The whole model is congruent with observed data as indicated by its non-significant probability. Paths values are standardized effects ± 1 standard error. Asterisks (*) denote significant coefficients (P <0.05) and "ns" denote non-significant coefficients (P> 0.05). Arrow width represents the strength of the causal link. Month, latent variable; S, number of species calling per month; P, photoperiod; T, mean monthly temperature; R, monthly rainfall; u1 to u4, associated error variable.