Figure 3

Association of Daphnia species distribution to mean Daphnia density and environmental descriptors of ten sampled lakes. The PCA plot displays (1) the projection of the original variables (see Additional file 2: Table S2) on to the first two components (coordinate scales: bottom and left) and (2) respective factorial loadings of lakes (coordinate scales: top and right). Arrows point to increasing importance for the respective variables. Each dot represents a lake. For lake abbreviations see Additional file 1: Table S1. Black dots: lakes inhabited by D. galeata; grey dots: lakes inhabited by D. longispina; white dots: neither parental species was detected (only hybrids were present). FASA and LERC (black dots with grey ring) are the only lakes where both species were detected. However, D. longispina was present at low frequencies: 0.3% (1 individual) and 2.5% (8 individuals), respectively – all samples pooled.