Abstract
Colonisation can expose organisms to novel combinations of abiotic and biotic factors and drive adaptive divergence. Yet, studies investigating the interactive effects of multiple abiotic factors on the evolution of physiological traits remain rare. Here we examine the effects of low salinity, low temperature, and their interaction on the growth of three North American populations of threespine stickleback (Gasterosteus aculeatus). In north-temperate freshwater habitats, stickleback populations experience a combination of low salinity and low winter temperatures that are not experienced by the ancestral marine and anadromous populations. Here we show that both salinity and temperature, and their interaction, have stronger negative effects on marine and anadromous populations than a freshwater population. Freshwater stickleback showed only a ~20% reduction in specific growth rate when exposed to 4 °C, while marine and anadromous stickleback showed sharp declines (82% and 74% respectively) under these conditions. The modest decreases in growth in freshwater stickleback in fresh water in the cold strongly suggest that this population has the capacity for physiological compensation to offset the negative thermodynamic effects of low temperature on growth. These results are suggestive of adaptive evolution in response to the interactive effects of low salinity and low temperature during freshwater colonisation.
Highlights
A growing number of studies have demonstrated that changes in abiotic factors can lead to local adaptation in physiological traits[1,2,3,4,5,6]
We predicted that a freshwater stickleback population would show patterns of growth consistent with local adaptation to both low salinity and cold winter temperatures when compared to patterns of growth in a marine and anadromous population
In the north-temperate zone, both low salinity and low winter temperatures have the potential to act as abiotic factors that could pose a barrier to permanent colonisation of fresh water, but few studies have evaluated the relative roles of these factors during colonisation and during subsequent evolutionary change
Summary
A growing number of studies have demonstrated that changes in abiotic factors can lead to local adaptation in physiological traits[1,2,3,4,5,6]. Previous studies have suggested that marine stickleback are at a growth disadvantage compared to freshwater stickleback in fresh water at an intermediate temperature[30], and that cold winter conditions reduce the growth of marine stickleback more than freshwater stickleback[35] These two studies separately investigated different abiotic factors that may act as agents of divergent natural selection in stickleback when they evolve freshwater residency, but did not assess the interactive effects of salinity and temperature or follow the effects of these environmental differences across a winter season. We predicted that a freshwater stickleback population would show patterns of growth consistent with local adaptation to both low salinity and cold winter temperatures when compared to patterns of growth in a marine and anadromous population
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
