Temperature-dependent versatility shapes invasiveness in the tropical freshwater gastropod Melanoides tuberculata

Abstract

Invasive species cause major losses in biodiversity worldwide and alter ecosystem functioning. Once established, invaders are often impossible to remove from ecosystems, especially in eco-insular systems such as the African Great Lakes. How intrinsic biological properties of invasive taxa interact with human-induced ecosystem modifications is a crucial factor determining invasiveness and our ability to anticipate, prevent and manage bioinvasions. Here we investigate the influence of temperature on key life-history traits, including fecundity, growth, offspring size, survival and parental immune investments, of invasive Asian Melanoides tuberculata (Müller, 1774) from Lake Malawi/Nyassa (morph LMI). We subjected populations of this parthenogenetic (clonal) lineage to uniform temperature treatments of 20 °C, 26 °C and 32 °C and monitored adult and juvenile life-history traits. Constitutive (preventative) and infection-induced immune investments of adults were estimated via antibacterial responses to a natural pathogen. Fecundity was low during our experiment and did not differ amongst temperature treatments, but a burst of offspring release occurred in the first two weeks of the experiment. Juvenile size and growth increased with temperature, which resulted in decreasing generation times. Juvenile mortality was, however, elevated at 32 °C. Temperature differences prompted a shift in immune investments. Under cold temperatures, adults invested in costly constitutive immunity, but they did not in warm environments, where strong investments in infection-induced immune responses occurred. This strategy may enable adults in warm environments to redirect energy from immunity to growth and reproduction, therewith, enhancing competitiveness at the cost of reduced offspring survival. We observed contrasting responses in various studied traits, suggesting that Melanoides tuberculata adopts compensatory mechanisms to cope with environmental changes. This versatility favours invasiveness and contributes to the competitive pressure which invasive Melanoides exerts on native taxa amid global warming and ecosystem change. Understanding the intricate interactions between bioinvasions and environmental change is essential for effective conservation of native species, the stability of their ecosystems and for policy development. Species-specific versatility of invasive species and associated competitive advantages remain understudied, but are critical to predict invasion dynamics in the context of multidimensional anthropogenic stressors, for informed risk assessment and decision-making.