Fig. 3
Partner preference index (PPind) of female M. arvalis of allopatric, parapatric or hybrid origin for males from the Western or Central lineages. A PPind of 1 would indicate a complete preference for Western males, −1 a complete preference for Central males and 0 the absence of a preference. Each female category is represented by a boxplot, the bold line being the median and the grey circle being the mean. A star above a boxplot marks a significant deviation from zero