Divergent Temperature Tolerances between two populations of the Splash-pool Copepod, Tigriopus californicus, on San Juan Island, WA

Abstract

Species living over large geographical ranges often have populations that are better adapted their local conditions (Helmuth et al. 2002). For example, populations of the splash-pool copepod, Tigriopus californicus, can tolerate higher temperatures as latitude decreases (Willett 2010). Studies on many organisms, including copepods, tend to look at a large geographical range and make generalizations about the thermal tolerance homogeneity of populations in specific latitude. By doing this we ignore possible effects of changing climate on some populations of copepods in areas that geographically are considered more tolerant. This study demonstrates a significant difference in the lethal temperature tolerance between two populations 30 kilometers apart on San Juan Island, WA. These sites are relatively close together compared to other studies. If we know that geographically close populations may be affected differently by climate change, then we may be more specific and cautious with our predictive modeling, not treating all populations the same.