Natural toxins leached from Eucalyptus globulus plantations affect the development and life-history of anuran tadpoles

Abstract

Rapid human-induced transformation of habitats is presenting organisms with challenging novel environmental conditions. Nowadays, extensive areas of the world are covered by exotic plantations, and among these, eucalypt plantations stand out for their worldwide occurrence. These novel environments probably threaten the persistence of native species, with several studies reporting biodiversity losses in these transformed areas. However, the effects of such habitat alteration on life-history traits that potentially constrain the ecology of individuals have been poorly explored. In a mesocosm experiment, we exposed tadpoles of three anuran species (Rana temporaria, Alytes obstetricans, and Pelophylax perezi) to the leachates of natural oak trees and exotic eucalypt trees to explore how the transformation of natural forests into eucalypt plantation affects the expression of behavioural and morphological traits and immune response. While anti-predatory responses appeared not to be impacted by leachate type, tadpoles exposed to eucalypt leachates differed in morphology and growth, and exhibited weaker immune responses and smaller size at metamorphosis than those exposed to oak leachates. Some of the responses were also species-specific, suggesting that some species are likely to be more sensitive than others to novel chemicals. We conclude that the poor quality of eucalypt leaf litter (e.g., its low nutrient content), low amount of food (e.g., periphyton), and the presence of toxic detritus and leachates can have important stress-related consequences for the critical early stages of development in anurans.