Capacity for thermal acclimation differs between populations and phylogenetic lineages within a species

Abstract

Summary1. Within-individual plasticity (acclimation) counteracts potentially negative physiological effects resulting from environmental changes and thereby maintains fitness across a broad range of environments. The capacity for the acclimation of individuals may therefore determine the persistence of populations in variable environments. 2. We determined phylogenetic relationships by Amplified Fragment Length Polymorphism (AFLP) analysis of six populations of mosquitofish (Gambusia holbrooki) from coastal and mountain environments and compared their capacity for thermal acclimation to test the hypotheses that acclimation capacity is greater in more seasonal environments with less diurnal variability, that acclimation is genetically constrained and that demographic processes determine acclimation capacity. 3. We show that populations are divided into distinct genetic lineages and that populations within lineages have distinct genetic identities. There were significant differences in the capacity for acclimation between traits (swimming performance, citrate synthase and lactate dehydrogenase activities), between lineages and between populations within lineages. 4. We rejected the hypothesis that climatic conditions (coastal vs. mountain) determined the capacity for acclimation, but accepted the hypotheses that demographic processes and genetic constraint influenced thermal acclimation. 5. The importance of our data lies in proof of concept that there can be substantial variation in thermal plasticity between populations within species. Similar responses are likely to be found in other species that comprise structured populations. Many predictions of the impact of climate change on biodiversity assume a species-specific response to changing environments. Based on our results, we argue that this resolution can be too coarse and that analysis of the impacts of climate change and other environmental variability should be resolved to a population level.

Physiological responses of ectotherms to daily temperature variation

“…What determines the capacity for thermal acclimation is complex, and may be dependent on several factors including phylogenetic history and environmental conditions at multiple time scales (Seebacher et al, 2012). Limnodynastes peronii and L. tasmaniensis are closely related yet experience a greater difference in environmental temperatures than that between L. tasmaniensis and P. ornatum.…”

Effects of size and sex on swimming performance and metabolism of invasive mosquitofish Gambusia holbrooki

“…1 body length s À1 ) every 20 min, until the fish could no longer swim due to fatigue (Hammer 1995;Jain et al 1997;Farrell 2008;Seebacher et al 2012). The test section (170 ml volume, 100 mm length 9 26.4 mm internal diameter) was laterally covered with nonreflecting white screens to avoid disturbing fish by 'mirror effects'.…”

“…Therefore, data on swimming capacity and metabolism may help to reveal the potential competition for space in the water column with a variety of native fishes (e.g. Nicoletto 1991;Kolok & Oris 1995;Plaut 2002;Seebacher et al 2012). For example, in the Iberian Peninsula, mosquitofish were observed to disrupt the foraging behaviour of the endemic cyprinid, Squalius alburnoides, in flowing waters (Almeida & Grossman 2012).…”

Consequences of complex environments: Temperature and energy intake interact to influence growth and metabolic rate

“…Because thermal plasticity can be genetically constrained (e.g., Seebacher et al, 2012), inter-individual variation may obscure the relative importance of thermal acclimation versus that of thermal constraint. We addressed this potential confounding factor through two aspects of our experimental design.…”