Data for: Predictable local adaptation in butterfly photoperiodism but not thermal performance along a latitudinal cline

In seasonal environments, organisms must synchronize their life cycles to conditions favorable for growth and reproduction. Because season length varies geographically, local adaptation should arise in traits that regulate phenological responses. Geographic photoperiodism clines are well-known, but comparable studies on thermal performance are equivocal and often overlook non-linear responses. Therefore, we examined local adaptation in plastic responses to both photoperiod and temperature along a 752 km latitudinal cline, by comparing four Swedish populations of the butterfly Pieris napi. Using a common garden design, we estimated (1) photoperiod response curves for diapause induction and (2) thermal performance curves for development and growth rates. We show that differences in photoperiodism follow the expected geographical pattern, where diapause is induced at longer daylengths in northern populations (where growth seasons are short and summer days long). However, population differe..., , , # Data for: Predictable local adaptation in butterfly photoperiodism but not thermal performance along a latitudinal cline

We collected data on development, growth, and diapause parameters in four different populations of the Swedish butterfly, *Pieris napi*, in different temperature and photoperiod treatments. We find clear patterns of local adaptation in photoperiodic responses but not in thermal responses. Data for the thermal treatments for development and growth are combined in \"development_data.txt\", and data for photoperiod treatments can be found in \"diapause_data.txt\". We also provide data on population observations (\"skane_obs.txt\", \"stockholm_obs.txt\", \"dalarna_obs.txt\", \"vasternorrland_obs.txt\"); on temperature data recorded by Swedish weather stations (\"ws_horby.txt\", \"ws_stockholm.txt\", \"ws_mora.txt\", \"ws_lungo.txt\"); and our sampling locations (\"sampling_weatherstation_location.txt\") that were used to produce Figure 1.

## Description of the data and file structure

The ...