title: Metabolic and reproductive plasticity of core and marginal populations of the eurythermic saline water bug Sigara selecta (Hemiptera: Corixidae) in a climate change context.
abstract: Ongoing climate change is driving dramatic range shifts in diverse taxa worldwide, and species responses to global change are likely to be determined largely by population responses at geographical range margins. Here we investigate the metabolic and reproductive plasticity in response to water temperature and salinity variation of two populations of the eurythermic saline water bug Sigara selecta: one population located close to the northern edge of its distribution, in a relatively cold, thermally stable region (SE England - 'marginal'), and one close to the range centre, in a warmer and more thermally variable Mediterranean climate (SE Spain - 'core'). We compared metabolic and oviposition rates and egg size, following exposure to one of four different combinations of temperature (15 and 25°C) and salinity (10 and 35gL-1). Oviposition rate was significantly higher in the marginal population, although eggs laid were smaller overall. No significant differences in oxygen consumption rates were found between core and marginal populations, although the marginal population showed higher levels of plasticity in both metabolic and reproductive traits. Our results suggest that population-specific responses to environmental change are complex and may be mediated by differences in phenotypic plasticity. In S. selecta, the higher plasticity of the marginal population may facilitate both its persistence in current habitats and northward expansion with future climatic warming. The less plastic core population may be able to buffer current environmental variability with minor changes in metabolism and fecundity, but could be prone to extinction if temperature and salinity changes exceed physiological tolerance limits in the future.
authors.affiliation: Departamento de Ecología e Hidrología, Facultad de Biología, Campus de Espinardo, 30100, Universidad de Murcia, Murcia, Spain. Electronic address: joseantonio.carbonell@um.es.
authors.forename: J A
authors.initials: JA
authors.lastname: Carbonell
authors.affiliation: Marine Biology and Ecology Research Centre, School of Marine Science and Engineering, University of Plymouth, Davy Building, Drake Circus, Plymouth PL4 8AA, UK.
authors.forename: D T
authors.initials: DT
authors.lastname: Bilton
authors.affiliation: Département de Biologie Chimie et Géographie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, Québec G5L 3A1, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Calosi
authors.affiliation: Departamento de Ecología e Hidrología, Facultad de Biología, Campus de Espinardo, 30100, Universidad de Murcia, Murcia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Millán
authors.affiliation: School of Life Sciences, University of Sussex, Falmer, Brighton, Sussex BN1 9QG, UK.
authors.forename: A
authors.initials: A
authors.lastname: Stewart
authors.affiliation: Departamento de Ecología e Hidrología, Facultad de Biología, Campus de Espinardo, 30100, Universidad de Murcia, Murcia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Velasco
mesh_terms: D000818:Animals; D017753:Ecosystem; D004734:Energy Metabolism; D005060:Europe; D020062:Heteroptera / Q000502:physiology*; D010058:Oviposition; D010063:Ovum / Q000502:physiology; D000068357:Saline Waters / Q000032:analysis; D013030:Spain; D000071436:Thermotolerance
keywords: Ecophysiology; Fecundity; Global change; Metabolic rate; Range margins; Trade-offs