Eco‐immunology and bioinvasion: revisiting the evolution of increased competitive ability hypotheses

Abstract

Immunity is at the core of major theories related to invasion biology. Among them, the evolution of increased competitive ability (EICA) and EICA‐refined hypotheses have been used as a reference work. They postulate that the release from pathogens often experienced during invasion should favour a reallocation of resources from (costly) immune defences to beneficial life‐history traits associated with invasive potential. We review studies documenting immune changes during animal invasions. We describe the designs and approaches that have been applied and discuss some reasons that prevent drawing generalized conclusions regarding EICA hypotheses. We detail why a better assessment of invasion history and immune costs, including immunopathologies and parasite communities, could improve our understanding of the relationships between immunity and invasion success. Finally, we propose new perspectives to revisit the EICA hypotheses. We first emphasize the neutral and adaptive mechanisms involved in immune changes, as well as timing of the later. Such investigation will help decipher whether immune changes are a consequence of pre‐adaptation, or the result of postintroduction adaptations to invasion front conditions. We next bring attention to new avenues of research that remain unexplored, namely age‐dependent immunity and gut microbiota, potential key factors underlying adaptation to invasion front environment and modulating invasion success.

Invasion history alters the behavioural consequences of immune system activation in cane toads

“…More generally, invasive species offer exceptional opportunities as natural experiments to study evolutionary processes that shape the immune system. The role of the immune system as both a target of selection and as a determinant of invasion success is becoming increasingly recognised (Cornet et al., ; Dunn & Perkins, ). Studies on invasive species have identified the dangers of inappropriate autoimmune response or the energetic costs and trade‐offs associated with different defence strategies as potential determinants of invasion success (Brown, Phillips, et al., ; Lee & Klasing, ).…”

Immune and environment‐driven gene expression during invasion: An eco‐immunological application of RNA‐Seq

“…Such immune responses are also costly due to energetic expenditure (the reduction of nutrients available for partitioning across tissues due to their use in mounting immune responses; Klasing & Leshchinsky, 1999) and to the potential for collateral damage (tissue injury due to the effects of the immune response; Martin et al, 2010). Nonetheless, loss of immunocompetence (the ability to mount a normal immune response after exposure to an antigen; Janeway, Travers, & Walport, 2001) could render invaders susceptible to infection by novel pathogens and parasites in their introduced range (Cornet et al, 2016;Lee & Klasing, 2004). Nonetheless, loss of immunocompetence (the ability to mount a normal immune response after exposure to an antigen; Janeway, Travers, & Walport, 2001) could render invaders susceptible to infection by novel pathogens and parasites in their introduced range (Cornet et al, 2016;Lee & Klasing, 2004).…”

Fitness in invasive social wasps: the role of variation in viral load, immune response and paternity in predicting nest size and reproductive output

“…These nests can vary substantially in size and queen productivity (Barlow et al ). The expansion of a species’ range has been associated with changes in immunocompetence (Cornet et al ) and it has been hypothesized that low genetic diversity in social invasive species may affect immune responses on colony and individual level (Ugelvig and Cremer ). Recently, the common wasp has been shown to carry viral pathogens.…”