Terrestrial and Aquatic Ecology Commons^™

Female terrestrial isopods carry eggs and young throughout early development, a habit that places constraints on reproductive success. One such constraint is impaired locomotion during the brooding period. Brooding and non-brooding females were subjected to a negative-phototaxis experiment in which females moved away from a light source along a graduated surface. In both groups, velocity was positively and significantly correlated with distance traveled. Velocity and distance were also significantly associated with the physical dimensions of the exoskelton: larger females moved greater distances at faster speeds. Non-brooding females, however, moved significantly farther at significantly greater velocities than brooding females, suggesting that …

Because female Porcellio laevis (Isopoda: Oniscidea) carry eggs and young manca in a ventral marsupium, fecundity and body size are positively correlated. We examined female body size in November and February, a period in which breeding does not occur and changes in body size are unlikely to be attributed to growth. Our results from two consecutive years revealed several general patterns. First, the sex-ratio of individuals collected with baited traps was extremely female biased. Second, body size was significantly larger (as indicated by length of antennae and appendages) in samples collected during November than in those collected during February. Third, …