|| 要旨トップ | 目次 |||日本生態学会第61回全国大会 (2014年3月、広島) 講演要旨
一般講演（口頭発表） F0-05 (Oral presentation)
Males of Pagurus middendorffii show precopulatory guarding behavior, and male-male contests often occur between a guarding male and an intruder. Intruders use both self- and mutual-assessment in the contest, suggesting that they could use information from both own and opponent. If males distinguish between familiar and unfamiliar opponents, they may alter the contest behavior based on both the prior contest outcomes (win or lose) and the familiarity with the opponent (familiar or unfamiliar). To examine this hypothesis, we conducted experiments of male-male contests with two consecutive periods. When intruders lost the first contest, we used them in a second contest with (1) familiar opponent, (2) unfamiliar opponent had already won other intruders, or (3) unfamiliar opponent with no contest experience. By using AIC model selection, winner effect was detected for unfamiliar losers and was enhanced when winners fought with familiar ones. Although loser effect on unfamiliar opponent was not found, losers became less aggressive against familiar winners. Our study suggests the importance of familiarity with the opponents in loser effect during the male-male contests and the ability of the individual recognition in males of P. middendorffii.