Abstract
Although size-assortative pairing has been extensively studied in amphipods, the influence of time left to moult (TLM) on pairing decisions of male gammarids remains largely unexplored. Given that moulting males cannot guard their mates, we investigated the influence of TLM for males on size-assortative mating in the gammarid Gammarus aequicauda (Crustacea, Amphipoda). There was a significant relationship between TLM and size in males. Unpaired males were closer to their moult than paired ones. Among pairs, there was a significant positive relationship between male and female sizes and between male and female TLM values. However, males closer to the moult were paired with females of more varying sizes than were other males, suggesting that a decrease in TLM reduces choosiness in males. Although there was a significant relationship between TLM and size in males, size-assortative mating was independent of male TLM.