On Friday, 9 May 2025, biologist Alessandra Schnider successfully defended her PhD thesis at Hólar University, “Phenotypic plasticity in Mývatn threespine stickleback (Gasterosteus aculeatus): response to temperature and diet within and across generations”. Through an ambitious multi-generation rearing experiment, she showed how the interplay of temperature, food availability and genetics shapes morphology, behaviour and gene expression—not only in individual fish but also in their descendants. Her results provide fresh insight into the adaptive capacity of organisms in a changing world and will aid more targeted conservation and management of wild fish populations.