Meeting Abstract

33.2  Friday, Jan. 4  Evolution of decapod mating systems AKIRA, Asakura; Nat. Hist. Mus. Inst., Chiba asakura@chiba-muse.or.jp

The mating systems of decapod crustaceans are reviewed and classified according to life styles and male-female relations. The scheme employs criteria that focus attention on evolutionary, ecological, life historical, and social determinants of both male and female behavior, and by these criteria, 9 types of mating systems are distinguished. (1) Non-guard and soft female mating: Both males and females are free-living, and copulation occurs after they encounter and females molt (e.g. Penaeus monodon ). (2) Non-guard and hard female mating: Both males and females are free-living, and copulation occurs after they encounter but females do not molt (e.g. Penaeus vannamei , Panulirus homarus . (3) Mating with precopulatory guarding: A male guards a female one to several days before copulation (e.g. Diogenes , Pagurus ). (4) Polygamy: A male patrols areas that contain refuges occupied by females (e.g. Inachus phalangium ). (5) Monogamy: In many symbiotic and some free-living species, they are found in a heterosexual pair. They may live on or inside of other organisms such as corals, sponges, and algal tubes (e.g. Trapezia , Spongicola , Stenopus , Hymenocera ). (6) Mating associated with visual displays: In many intertidal and semi-terrestrial crabs, males conduct visual displays including species-specific dances to attract females, and copulation occurs in burrows of the males (e.g. Uca , Ilyoplax ). (7) Dwarf male mating: An extremely small male attaches near the gonopore of a free-living female (e.g. Emerita rathbunae ).(8) Reproductive swarm: In the pinnotherid crabs, mating occurs when a female is a free-swimming instar before she enters into her definitive host. (9) Non-coresidential: In hapalocarcinid crabs, female are sealed inside of a coral gall, and the male crab normally residing outside the gall is assumed to visit the gall for mating.