Primary data used to calculate predator-induced morphological changes in two Daphnia species-associated clones

The expression of inducible defences in reaction to an inconsistent predation pressure is especially well investigated in the freshwater keystone filter-feeder Daphnia. Out of their many inducible defences, which increase their fitness, the highest diversity of induced traits is found within their morphology. In recent time the focus of studies on these has switched, from the previously thoroughly covered large-scale defences, e.g., elongated/enlarged tail-spines, helmets and crests, to rather small-scale predator-induced changes. Inconspicuous spinules that cover the dorsal and ventral carapace margins have only rarely been featured in studies. We, therefore, tested two well-studied Daphnia species (D. magna and D. longicephala) for predator-induced changes concerning the spinules, i.e., their area of distribution relative to the body length (relative dorsal/ventral spinules-bearing area, relSBA) and their change in length (mean spinule length of the five central spinules along the dor...