Figure 4

Effect of intra-annual environmental seasonality on reproduction. Seasonal pattern of vole female per capita productivity (number of embryos per females) along year. The monthly average per capita embryo production (circles) with 80 percent confidence interval is calculated from field data. For the prediction (solid line with shaded area indicating the 70% confidence interval of coefficients estimate), only the seasonal component of the environment (the two components from the PCA summarizing 98.9% of the environment seasonality) was allowed to vary with the date. All other explanatory variables (size, body condition, abundances, plant productivity anomalies) were fixed at their mean value. Also the seasonal pattern of common vole reproduction is well explained by the seasonal variation of environment.