Variation in thermal tolerance of Tigriopus californicus among isolated populations and between life stages

Abstract

Climate change will alter life on Earth, but the specific impact on any given species is less certain. Most current forecasting models lump all members of a species under one climatic envelope, thus ignoring the possibility of local adaptation among isolated populations of a wide-ranging species to result in differing climatic needs for each population compared to the species as a whole. To provide experimental evidence of the importance of local adaptation, we test each life stage of seven populations of copepod Tigriopus californicus ranging fifteen degrees in latitude, expecting populations and possibly life stages to differ in thermal tolerance. Our results show populations living in cooler climates generally have a lower thermal tolerance, and also juveniles exhibit higher thermal tolerances than adults, which could affect how a population responds to changing conditions. Thus, it is important for models to consider the roles of adaptation and evolution in species survival.