Physiological plasticity in a successful invader: rapid acclimation to cold occurs only in cool-climate populations of cane toads (Rhinella marina)

• Published in: Conservation physiology 2018-01, Vol.6 (1), p.cox072-cox072
• Main Authors: McCann, Samantha M, Kosmala, Georgia K, Greenlees, Matthew J, Shine, Richard
• Format: Article
• Language: English
• Subjects: Biological invasions; Cane toad; Climate; Environmental aspects; Evolution (Biology); Evolutionary adaptation; Frogs; Introduced animals; Introduced species; Natural history; Novels; Physiological aspects; Proxy; Zoological research
• ISSN: 2051-1434; 2051-1434
• DOI: 10.1093/conphys/cox072

Invasive cane toads have been present in Australia and Hawai’i for ~80 years. Toads have invaded sites in each location that are cooler than their native range. These populations have both developed the ability to rapidly acclimate to cold conditions, decreasing their critical minimum temperature over just 12 h. Abstract Physiological plasticity may facilitate invasion of novel habitats; but is such plasticity present in all populations of the invader or is it elicited only by specific climatic challenges? In cold-climate areas of Australia, invasive cane toads (Rhinella marina) can rapidly acclimate to cool conditions. To investigate whether this physiological plasticity is found in all invasive cane toads or is only seen in cool climates, we measured the acclimation ability of toads from across Australia and the island of Hawai’i. We collected toads from the field and placed them at either 12 or 24°C for 12 h before measuring their righting response as a proxy for critical thermal minimum (CTmin). Toads from the coolest Australian region (New South Wales) demonstrated plasticity (as previously reported), with exposure to 12°C (vs. 24°C) decreasing CTmin by 2°C. In toads from other Australian populations, CTmins were unaffected by our thermal treatments. Hawai’ian toads from a cool, wet site also rapidly acclimated to cool conditions, whereas those from warmer and drier Hawai’ian sites did not. Thermal plasticity has diverged among populations of invasive cane toads, with rapid acclimation manifested only in two cool-climate populations from widely separated sites. Predictions about the potential range of invasive species thus must consider the possibility of geographic (intraspecific) heterogeneity in thermal plasticity; data from other parts of the species’ range may fail to predict levels of plasticity elicited by thermal challenges.