Plastic Aliens: Developmental Plasticity and the Spread of Invasive Species

Biological invasions are one of the worst threats to biodiversity conservation, ecosystem services and functionality, and human health. However, of the high number of organisms that are transported and introduced outside their native range, only a subset of them can survive, establish and spread in the novel area, becoming invasive. What determines the ability of an alien animal species to become invasive? There is an increasing awareness that the answer to this longstanding and crucial question is highly multifactorial, with some factors already well-discerned, and some not yet elucidated. In this book chapter, we focus on developmental plasticity, the permanent change in the developmental trajectory adopted by an organism in response to gene–environment interactions. Developmental plasticity is an important adaptive response to the obvious variability of biotic and abiotic environmental conditions over time. Yet, it can also promote the invasion of novel habitats, by favouring the optimal match between individual phenotypes and the new environment, during the early steps of an invasion. By relying on the available literature and focusing on animal invasions, we analyse the adaptive advantages conferred by developmental plasticity (i) in dealing with the new biotic and abiotic environment during the stage of introduction, (ii) in terms of reproductive rate and population growth, two crucial processes for overcoming the stages of establishment and (iii) in dispersal traits promoting the spread in the new environment. We conclude that, although acknowledged in previous literature, the actual contribution of developmental plasticity to the shaping of the ideal invader might have been underrated.