Latitudinal Differentiation in Copepod Growth: An Adaptation to Temperature

Abstract

We demonstrate the presence of significant differentiation in development rate, adult body length, and stomatic growth rate in the estuarine harpacticoid copepod Scottolana canadensis (Willey) collected from a broad range of latitudes (27°—43° N) and reared in the laboratory for several generations under the same conditions (15 g salts per 1000 g seawater, and 15°, 20°, 25°, or 28°C). The changing pattern of differential growth with increased temperature suggests local adaptation to maximize scope for growth under prevailing temperatures conditions; northern—derived individuals grew faster at low but not at high temperatures.