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Understanding how latitudinal temperature variation shapes local adaptation of life history strategies is crucial for predicting future responses to warming. Contrasting predictive frameworks explain how growth and other life history traits may respond to differing selective pressures across latitude. However, these frameworks have rarely been explored within the context of fluctuating environmental temperatures across longer (i.e., seasonal) time scales experienced in nature. Furthermore, consequences of growth differences for other aspects of fitness, including reproductive output, remain unclear. Here, we conducted a long-term (17-month) laboratory experiment to examine local adaptation in two populations of the predatory marine snail Urosalpinx cinerea separated by 8.6° latitude (1000 km). We reared F1 offspring in a common-garden design under two seasonally fluctuating temperature regimes (“warm” and “cold”, simulating field thermal conditions experienced by low- and high-latitude populations, respectively), quantifying temporal patterns in growth, maturation, and reproductive output. We identified striking divergence in life-history strategies between populations in the warm regime, with offspring from the low-latitude population achieving greater growth in their first year, and high reproductive output coupled with reduced growth in their second year. In contrast, the high-latitude population grew slower in their first year, but eventually attained larger sizes in their second year, at the expense of reduced reproductive output. Responses in the cold regime followed similar population-specific life-history patterns to those in the warm regime, although growth and reproductive output was reduced in both populations. Our data provides support for adaptive divergence across latitude consistent with the pace-of-life syndrome hypothesis, with the low-latitude population selected for a fast-paced life characterized by rapid development and early reproduction. In contrast, the high-latitude population exhibited slower growth and delayed maturation. Our results highlight the potential limitations of short-term comparisons of growth that do not account for longer-term processes, such as seasonal temperature variation and ontogenetic shifts in energy allocation and imply a radical reshaping of physiological performance and life history traits across populations under climate change. 

Marine organisms frequently inhabit intertidal zones that serve as refuges from predation and competition but are not optimal physiologically. Restoration practitioners working with intertidal species may similarly have to consider whether restoration success will be greater where conditions are more benign (usually lower in the intertidal) or where negative biotic interactions are reduced (usually higher in the intertidal). In cases where a target species has greater desiccation tolerance than its enemies, restoration may be more successful higher in the intertidal zone, despite potential performance trade-offs. In many US West Coast estuaries, non-native drill species can decimate native oyster populations, posing a challenge to restoration. Given that native Olympia oystersOstrea luridashould be better able to withstand tidal emersion than the non-native Atlantic oyster drillUrosalpinx cinerea, we explored using the high intertidal as a refuge from predation as a potential restoration technique. Using surveys and a field experiment, we investigated the recruitment, growth, and survival of oysters as well as drill abundance and predation over 3 tidal elevations. Oysters recruited and survived equally well at +0.1, +0.5, and +0.8 m mean lower low water, but juvenile oyster growth decreased with increasing elevation. In our experiment, predation on oysters was lower at the highest elevation than at low and mid elevations, but in natural populations there was a near complete absence ofO. luridaat any elevation whereU. cinereawas present. This suggests that a higher tidal elevation refuge is not a viable approach for oyster restoration in our study area.