Physiological mechanisms of adaptive developmental plasticity in Rana temporaria island populations

• Published in: BMC Evolutionary Biology
• Main Authors: Pablo Burraco, Ana Elisa Valdés, Frank Johansson, Ivan Gomez-Mestre
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2017
• Subjects: Amphibians; Corticosterone; Developmental plasticity; Evolutionary physiology; Oxidative stress; Telomere length; Evolution; QH359-425; Northern Sweden
• Online Access: https://doi.org/10.1186/s12862-017-1004-1; https://doaj.org/article/9902604f2b1a40ab96c94eaed5c4ed9d

Abstract Background Adaptive plasticity is essential for many species to cope with environmental heterogeneity. In particular, developmental plasticity allows organisms with complex life cycles to adaptively adjust the timing of ontogenetic switch points. Size at and time to metamorphosis are reliable fitness indicators in organisms with complex cycles. The physiological machinery of developmental plasticity commonly involves the activation of alternative neuroendocrine pathways, causing metabolic alterations. Nevertheless, we have still incomplete knowledge about how these mechanisms evolve under environments that select for differences in adaptive plasticity. In this study, we investigate the physiological mechanisms underlying divergent degrees of developmental plasticity across Rana temporaria island populations inhabiting different types of pools in northern Sweden. Methods In a laboratory experiment we estimated developmental plasticity of amphibian larvae from six populations coming from three different island habitats: islands with only permanent pools, islands with only ephemeral pools, and islands with a mixture of both types of pools. We exposed larvae of each population to either constant water level or simulated pool drying, and estimated their physiological responses in terms of corticosterone levels, oxidative stress, and telomere length. Results We found that populations from islands with only temporary pools had a higher degree of developmental plasticity than those from the other two types of habitats. All populations increased their corticosterone levels to a similar extent when subjected to simulated pool drying, and therefore variation in secretion of this hormone does not explain the observed differences among populations. However, tadpoles from islands with temporary pools showed lower constitutive activities of catalase and glutathione reductase, and also showed overall shorter telomeres. Conclusions The observed differences are indicative of physiological costs of increased developmental ...