Fig. 4

Stable isotope values from the three Lake Engervann stickleback lateral plate morphs and putative prey items based on δ¹³C and δ¹⁵N. The upper figure shows stable isotope values of different prey items sampled in different parts of Lake Engervann (upper, midle and lower sections) and outside in a more marine environment close to the Kalvøya Island and in a marine pelagic environment close to the Steilene Island in the inner Oslofjord. All prey items within the five nominal environmental categories are grouped using colors. In the lower figure is given the total range of individual stable isotope values in the threespine stickleback in Lake Engervann (thick black line) when grouping sampling time and sampling site into one analysis. Also, 50% density plots are given for the completely plated morph (black), partially plated morph (grey), and lowplated morph (light grey). The filled red circle denotes the mean value for all threespine sticklebacks analyzed from Lake Engervann