Designing eco-evolutionary experiments for restoration projects: Opportunities and constraints revealed during Stickleback introductions

Eco-evolutionary experiments are typically conducted in semi-unnatural controlled settings, such as mesocosms; yet inferences about how evolution and ecology interact in the real world would surely benefit from experiments in natural uncontrolled settings. Opportunities for such experiments are rare but do arise in the context of restoration ecology – where different “types” of a given species can be introduced into different “replicate” locations. Designing such experiments requires wrestling with consequential questions. Q1. Which specific “types” of a focal species should be introduced to the restoration location? Q2. How many sources of each type should be used – and should they be mixed together? Q3. Which specific source populations should be used? Q4. Which type or population(s) should be introduced into which restoration sites? We recently grappled with these questions when designing an eco-evolutionary experiment with threespine stickleback (Gasterosteus aculeatus) introduced into nine small lakes and ponds on the Kenai Peninsula in Alaska that required restoration. After considering the options at length, we decided to use benthic versus limnetic ecotypes (Q1) from a mixture of four source populations of each ecotype (Q2) selected based on trophic morphology (Q3), and introduced into restoration lakes in a paired design (Q4). We hope that the present paper outlining the alternatives and resulting choices will provide the rationales clear for future studies leveraging our experiment, while also proving useful for investigators considering similar experiments in the future.