The behavior of Gammarus aequicauda (crustacea, amphipoda) during predation on chironomid larvae: Sex differences and changes in precopulatory mate‐guarding state

• Published in: Journal of experimental zoology. Part A, Ecological and integrative physiology Ecological and integrative physiology, 2021-07, Vol.335 (6), p.572-582
• Main Authors: Shadrin, Nickolai, Yakovenko, Vladimir, Anufriieva, Elena
• Format: Article
• Language: English
• Subjects: amphipoda; Aquatic crustaceans; Aquatic ecosystems; Benthic fauna; Benthos; Breeding success; chironomidae; Cooperation; Costs; Crustaceans; Energy; Feeding behavior; Feeding habits; Females; Food resources; Foraging; Foraging behavior; Gammarus; Gender aspects; Gender differences; Guarding behavior; Interspecific relationships; Invertebrates; Larvae; Males; Mate guarding; Populations; precopulatory mate guarding; Predation; Predators; predatory; Prey; Reproduction; Sex; Sex differences; Shellfish; Swimming; Zoobenthos
• ISSN: 2471-5638; 2471-5646
• DOI: 10.1002/jez.2500

The foraging behavior determines the diet size influencing the growth and reproduction of a predator and its prey populations. Amphipods play a key role in various aquatic ecosystems. Gammarus aequicauda is an abundant widespread omnivorous species and the only known amphipod species of hypersaline waters. Its predation can suppress the populations of planktonic and benthic invertebrates. Males of G. aequicauda actively eat chironomid larvae but there is no data on predatory females. Experiments were conducted to study sex‐related differences in feeding behavior including during precopulatory mate guarding (PCMG). There were significant sex differences in feeding characteristics. For females, calculations showed that maximum consumption could be 3–4 chironomid larvae per day and for males about 9–10 larvae per day. During PCMG, males did not feed and females fed as efficiently as single females. Males transported females and alone carrying the energetic costs of swimming during PCMG. Less expenditure of energy on swimming means more energy for reproduction for females. This allows more energy‐efficient use of food resources and increases the reproductive success of the population. There are currently two alternative views on PCMG among crustaceans. 1. It is a sexual conflict between males and females serving as a male adaptive strategy to achieve a female during strong male competition, while females bear many costs during the long guarding period. 2. There is also the opposite view that pairs get energetic benefits from long PCMG. Obtained data suggest that PCMG is likely to be intersexual cooperation and not intersexual conflict. Sex differences in feeding of Gammarus aequicauda (Crustacea, Amphipoda) Research Highlights Per day, single females consume 3–4 chironomid larvae, and males 9–10. In precopulatory mate‐guarding state (PCMG), males don't eat but females have a consumption rate as in a single state. PCMG is intersexual cooperation, not intersexual conflict.