The relationship between chemical constitution and antifungal activity in arylhydrazono -isoxazolone compounds

From a study of compounds related to the mildew fungicide, 4-o-chloro-phenylhydrazono-3-methyl-5-isoxazolone, it is apparent that high antifungal activity is associated with the arylhydrazonoisoxazolone structure. Differences in the relative effectiveness of o-chlorophenylhydrazono-, m-chlorophenyl-hydrazono- and phenylhydrazono- derivatives against Botrytis fabae on beans and Podosphaera leucotricha on apples may be due to different modes of action. Several possible mechanisms of action are discussed.     

The cost of polygyny and the evolution of female care in poison frogs

Previous research on a variety of organisms indicates that polygyny can impose a cost on the reproductive success of females. Some authors have hypothesized that this cost may have caused the evolution of female parental care from paternal or biparental care in some lineages, particularly in poison frogs of the genus Dendrobates. In this paper, we evaluate the assumptions and theoretical implications of this hypothesis and present several game-theoretic models that clarify some of the issues. We conclude that a cost of polygyny is unlikely to drive a female care strategy to fixation on its own; however, if caring males suffer a cost of lost mating opportunities then a cost of polygyny may destabilize male care and result in the evolution of uniparental female care. A cost of polygyny on its own may be able to drive a transition from male care to biparental care. We also discuss other factors that may have influenced the evolution of parental care in the poison frogs, including results from recent field and laboratory research, and we evaluate the possibility that female care evolved from biparental, as opposed to male care.