The significance of biparental care in the brown bullhead, Ictalurus nebulosus

Parental care in the brown bullhead is characterized by variation in the participation of each sex. Most broods are attended by both sexes, but some are attended by a male alone, or rarely, a female alone. Two care-givers were more successful than one alone in fostering offspring survival. However, there was no significant difference between two care-givers and one alone in the proportion of time that broods were unattended. Potential brood predators were chased less frequently by one adult alone than by adults aided by their mate. This difference may be unimportant since two adults simultaneously attended their brood only 19% of the time. Males alone attended their broods a significantly greater proportion of time than did either males or females aided by their mates. This difference suggests that males alone sustain a greater cost of care-giving (starvation and therefore reduced future reproduction) than do males aided by their mates. Thus, males alone may more often leave broods (and not return) than males that are aided in care-giving. The differential success observed may be due to a difference in the likelihood that the male (the principal care-giver) leaves the brood permanently, rather than differences in the quality of care one or two adults provide. I suggest that two care-givers are more successful than one because the net benefits of care-giving exceed the net benefits of leaving for males when aided by their mates.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42631/1/10641_2004_Article_BF00005153.pd

The parental care behaviour of Paratilapia polleni (Perciformes, Labroidei), a phylogenetically primitive cichlid from Madagascar, with a discussion of the evolution of maternal care in the family Cichlidae

The parental behaviour of the Madagascan cichlid, Paratilapia polleni , was studied in the laboratory. According to current hypotheses of phylogenetic intrarelationship for the family Cichlidae, Paratilapia is a representative of a phylogenetically primitive cichlid lineage, and as such is of particular interest in comparative evolutionary studies. Given the basal phylogenetic placement of Paratilapia it seems reasonable to expect that, if maternal participation in brood care arose within the extant Cichlidae, then the proposed plesiomorphic system of extensive male care of eggs and embryos may be retained in this taxon. This is not the case, and already by the fertilized-egg interval male and female roles in Paratilapia are strongly differentiated with the female as the primary care giver. In addition to specialized behavioural roles, a unique egg morphology and mobile egg mass is described for Paratilapia . The results of the study are discussed in the context of theories of the evolution of maternal brood care within the Cichlidae.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42636/1/10641_2004_Article_BF00004768.pd

Foraging on patchily distributed prey by a cichlid fish (Teleostei, Cichlidae): A test of the ideal free distribution theory

Cichlid fish (Aequidens curviceps) distributed themselves and allocated their foraging time between two drift food patches in close approximation to the patch profitability ratio, as predicted by the ideal free distribution theory. The fish thereby achieved similar average feeding rates in the two patches, in two of three patch profitability ratio experiments. However, one major assumption of the ideal free model was violated, since individual fish differed in their competitive abilities for limited food resources, which resulted in unequal payoffs among individuals within each patch. Individual variation in feeding rates, and thus in competitive ability, was not related to despotism, but perhaps rather to individual differences in perceptual ability and in the ability to learn which patch was currently the more profitable. The strategy used by the fish to assess patch profitability included sampling available patches. However, individual fish switched (sampled) patches with varying frequency. Sampling had an associated cost, since high-frequency switchers had lower feeding rates on average than low-frequency switchers. Differences in foraging strategy among the fish therefore contributed to the observed in-equality in individual payoffs within patches