The Braveheart amphipod: A review of responses of invasive Dikerogammarus villosus to predation signals

Abstract

Predator pressure is a fundamental force driving changes at all levels of the community structure. It may protect native ecosystems from alien species. Therefore, resistance to diverse predators resulting from a universal anti-predator strategy seems crucial for invasion success. We present a comprehensive review of the responses of an invasive amphipod Dikerogammarus villosus to sympatric and allopatric predator signals. We summarize diverse aspects of the gammarid anti-predator strategy, including predator identification, morphological and behavioral adaptations, effectiveness of shelter use and resistance to indirect predator effects. The response of D. villosus is independent of predator species (including totally allopatric taxa), which assures the high flexibility of its predator recognition system. It has harder exoskeleton and better capability of utilizing shelters compared to other gammarids, resulting in relatively high resistance to predators. Therefore, it can use predator kairomones as indirect food signals (sharing the diet with the predator) and follow the predator scent. This resistance may allow D. villosus to reduce the costs of its physiological responses to predators and sustain growth in their presence. This might facilitate the invasion success by increasing its competitive advantage.

Both Light Stimuli and Predation Risk Affect the Adult Behavior of a Stygobiont Crustacean

“…While recent phylogenetic studies revealed that predator-prey interactions are important in shaping antipredator morphological structures in Niphargus species [54], behavioral studies do not acknowledge this concept, which is similar for studies conducted on stygobiont crustaceans. An enhanced sensitivity to different predator cues exists in surface-dwelling freshwater amphipods [55][56][57][58], and this suggests that similar investigations can also be performed on subterranean-dwelling species. In our experiment, we used adult individuals, for which it was not possible to know their age or previous experience.…”