Fig. 2.
Experimental design to (A) measure thermal niche of genotypes and their expected fitness in the tested temperatures and (B) quantify temperature-dependent habitat choice at emigration and immigration. (A) The fitness of each genotype along a thermal gradient (11 °C to 39 °C) was quantified to reconstruct its thermal niche (SI Appendix, Fig. S1). From these thermal niches, we quantified the expected fitness at each focal environmental condition (e.g., 35 °C expected fitness: growth rate at 35 °C relative to performance at optimum) (Methods). (B) Genotypes were initially inoculated in the central patch of three-patch systems (start patch and temperature set at either 27 °C or 35 °C) connected to one 27 °C patch and one 35 °C patch. Genotypes were thus allowed to choose their habitat at emigration (stay or leave the start patch) and immigration (where to settle). T. thermophila silhouette was obtained from Phylopic.org.