Sex or food? Effects of starvation, size and diet on sexual cannibalism in the amphipod crustacean Gammarus zaddachi

Abstract

Cannibalism of females by males before, during or immediately following sex has been attributed to misidentification of females, rejection of females as mates and prioritisation of feeding over reproduction. In the gammarid amphipod Gammarus zaddachi, males demonstrate that they have identified a female and accepted her as a suitable mate by engaging in precopula pairing behaviour. However, a male may later decide to eat the female after pairing with her. Laboratory experiments were performed in which survival of females in precopula pairs of G. zaddachi was monitored after their male partners had been subjected to starvation, herbivorous diets or diets containing animal matter. These indicate that the female is less likely to survive when she is abnormally small relative to the male, when the male is at risk of death by starvation or when the male's diet has lacked animal content. Decisions by males to forgo reproductive opportunities in favour of cannibalism, even after engaging in costly mate-guarding behaviour, emphasise the importance of carnivory in the trophic ecology of Gammarus species.

CanGammarus aequicauda(Amphipoda) suppress a population ofBaeotendipes noctivagus(Chironomidae) in a hypersaline lake? A case of Lake Moynaki (Crimea)

“…The general conclusion from this follows that the role of G. aequicauda in the regulation of the number of chironomid larvae depends on their abundance and the characteristics of the habitats. At the same time, as noted earlier (Remy et al., 2017; Shadrin et al., 2020a,2020b), the populations of G. aequicauda cannot exist and reproduce without animal food at all, like as some other Gammarus species (Dick, 1995; Ironside et al., 2019; Remy et al., 2017). Cannibalism was observed in Gammarus if animal food was absent (Dick, 1995; Ironside et al., 2019; Shadrin et al., 2020a).…”

Complexity of trophic relationships between Gammarus aequicauda (Amphipoda) and Eucypris mareotica (Ostracoda) in a hypersaline lake

“…Gammarus females generally being less active than males (Peeters et al, 2009; Shadrin et al, 2021b; van den Berg et al, 2023), and it may contribute to those sex feeding differences. During the precopulatory mate‐guarding state, females continue to feed normally, but males do not feed, and therefore must feed intensively before entering this state (Ironside et al, 2019; Plaistow et al, 2003; Shadrin et al, 2021b).…”