The ongoing climate change will affect egg incubation temperatures and thus changethe early development of fish, which can have a variety of influences in later lifestages. I tested whether the incubation temperature during the earliest stages ofdevelopment changed body shape and eye size in juvenile trout (Salmo trutta) whenthe average temperature was 4.4 and 7.1 °C. This temperature difference simulatesincreases predicted in climate change scenarios. Based on previous studies, Ihypothesized that S. trutta from eggs exposed to cold incubation temperatures willhave deeper bodies than warm-incubated S. trutta. I also predicted that the eye sizeof cold-incubated trout would be larger than that of warm-incubated trout. The fishincubated at cold temperature differed from the fish incubated at a warmertemperature by having a larger head region but there was no difference in eye size.These results suggest that changes in the incubation temperature induced by awarmer climate can lead to changes in body shape, which raises questions about theecological consequences of the changes. / Den pågående klimatförändringen kommer att påverka ägginkubationstemperatureroch därmed förändra den tidiga utvecklingen hos fiskar, vilket kan ha en mängd olikaeffekter i senare livsstadier. Jag testade om inkuberingstemperaturen under detidigaste utvecklingsstadierna ändrade kroppsform och ögonstorlek hos juvenilaöringar (Salmo trutta) när temperaturen i genomsnitt var 4,4 respektive 7,1 °C.Denna temperaturskillnad simulerar ökningar som förutspås iklimatförändringsscenarier. Baserat på tidigare studier ställde jag som hypotes attöring från ägg som utsätts för kalla inkubationstemperaturer kommer att ha djuparekroppar än varminkuberad öring. Jag förutspådde också att ögonstorleken hoskallinkuberad öring skulle vara större än för varminkuberad öring. Fisken sominkuberades vid kall temperatur skilde sig från fisken som inkuberades vid varmaretemperatur genom att ha en större huvudregion men det fanns ingen skillnad iögonstorlek. Dessa resultat tyder på att förändringar i inkubationstemperaturen sominduceras av ett varmare klimat kan leda till förändrad kroppsform som därmedväcker frågor om de ekologiska konsekvenserna av förändringarna.

Phenotypic plasticity is the ability of an organism to express different phenotypes depending on the biotic or abiotic environment. In many cases, the response to the environment is beneficial to the individual and can therefore represent adaptive phenotypic plasticity. An example includes morphological and life-historical response to predators. Because there has been a weak interest in the effect of these morphological changes, and it often assumes, but rarely shown, that predator-induced changes are adaptive. I tested how different variables, such as maximum acceleration and velocity, were related to each other in different Gosner stages. Eggs and tadpoles of the species Rana temporaria were exposed to various predator enclosures, a control, a stalking predator (European Perch, Perca fluviatilis), and an ambush predator (dragonfly larvae). The tadpoles mean weight, maximum acceleration and velocity, mobility, boldness, and morphological changes in various Gosner stages were analyzed. My tests showed a significant difference in tadpole weight and their morphology, however, there were no differences in speed, acceleration, boldness or mobility. The morphometric analysis of the tadpoles showed a significant change of tadpoles in the perch treatment compared to the tadpoles in the control. The tadpoles in the perch treatment showed a higher TH/TL (tail height/tail length) ratio, and were overall heavier, than the tadpoles in the control, but no significant change compared to the tadpoles in the dragonfly treatment. This shows that the kairomones and alarm cues triggered a large morphological change, but the effect of the change requires more research.