Figure legends

Fig. 1. Body size of H. oligactis polyps from three male and three female strains and cultured for one week on 18 ºC (cool summer, CS) or exposed to a simulated one-week heatwave of 23 ºC (warm summer, WS). A simulated summer heatwave significantly reduces both male and female body size (see Results).

Fig. 2. Sexual reproduction in male H. oligactis polyps belonging to three distinct strains exposed to four distinct temperature regimes: CS-CW (18 ºC summer – 8 ºC winter; control group), WS-CW (23 ºC summer – 8 ºC winter), CS-WW (8 ºC summer – 12 ºC winter) or WS-WW (23 ºC summer – 12 ºC winter). The summer treatment lasted for one week, while the winter treatment lasted 21 weeks. The graph shows the time elapsed until the appearance of the first gonads after cooling (A), the maximum number of testes (B) and temporal changes in the frequency of sexual individuals (C). Photograph of a male individual with mature testes is shown on panel D for illustration.

Fig. 3. Sexual reproduction in female H. oligactis polyps belonging to three distinct strains exposed to four distinct temperature regimes: CS-CW (18 ºC summer – 8 ºC winter; control group), WS-CW (23 ºC summer – 8 ºC winter), CS-WW (8 ºC summer – 12 ºC winter) or WS-WW (23 ºC summer – 12 ºC winter). The summer treatment lasted for one week, while the winter treatment lasted 21 weeks. The graph shows the time elapsed until the appearance of the first gonads after cooling (A), the total number of eggs (B) and temporal changes in the frequency of sexual individuals (C). Photograph of a female individual with mature eggs is shown on panel D for illustration.

Fig. 4. Asexual reproduction and survival in H. oligactis polyps belonging to three male and three female strains, exposed to four distinct temperature regimes: CS-CW (18 ºC summer – 8 ºC winter; control group), WS-CW (23 ºC summer – 8 ºC winter), CS-WW (8 ºC summer – 12 ºC winter) or WS-WW (23 ºC summer – 12 ºC winter). The summer treatment lasted for one week, while the winter treatment lasted 21 weeks. The graph shows the total number of buds produced during the 22 weeks of the experiment (A) and proportion of individuals surviving (C). The number of surviving animals from each strain and treatment group is shown on the bars. Photographs of an asexual individual (B) and a senescent individual (D) are shown for illustration.