Comparative reproductive biology of Ariolimax californicus and A. dolichophallus (Gastropoda; Stylommiatophora)

Summary

Traits which differ among species in a genus are considered to be the product of relatively rapid evolution. Laboratory studies indicate that copulation differs between two species of the banana slug Ariolimax with A. dolichophallus having a pattern of a single, long duration (typically greater than 1 h) intromission which is simultaneously reciprocal, and A. californicus having mating encounters typically involving a bout of brief (typically 10–20 min) unilateral intromissions. Reciprocal apophallation was observed for both species. Field observations confirm simultaneously reciprocal copulation and apophallation in A. dolichophallus. Mating was more frequent in the spring and summer months. In laboratory studies the two species also differed in life history parameters; mean growth rate was greater in A. californicus than A. dolichophallus, whereas eggs are larger in A. dolichophallus (range = 0.33–0.5 g; n=59) than in A. californicus (range= 0.08–0.27 g; n=164).     

Cupin: A candidate molecular structure for the Nep1-like protein family

Background  

NEP1-like proteins (NLPs) are a novel family of microbial elicitors of plant necrosis. Some NLPs induce a hypersensitive-like response in dicot plants though the basis for this response remains unclear. In addition, the spatial structure and the role of these highly conserved proteins are not known.     

Correlation Between Nest and Duckling Survival of Mallards Breeding in Saskatchewan

Abstract: Few studies have estimated reproductive and survival parameters of breeding ducks simultaneously, although such efforts can reveal relationships among vital rates. We estimated survival of mallard (Anas platyrhynchos) nests and duckling on 8 study sites in south-central Saskatchewan during spring and summer 2000 and 2001. We observed a strong positive correlation between these parameters (r = 0.914) and through analysis of residual values found 14% of the relationship was explained by a predator-removal treatment, 26% by year effects, 44% by spatial variation, and 16% unexplained. Potential mechanisms include similar environmental factors influencing both parameters (e.g., predators) and positive density dependence. Information regarding covariation among vital rates is important in construction and interpretation of population growth models describing population dynamics of mallards and other upland-nesting ducks.