Paternity of subordinates raises cooperative effort in cichlids

Background In cooperative breeders, subordinates generally help a dominant breeding pair to raise offspring. Parentage studies have shown that in several species subordinates can participate in reproduction. This suggests an important role of direct fitness benefits for cooperation, particularly where groups contain unrelated subordinates. In this situation parentage should influence levels of cooperation. Here we combine parentage analyses and detailed behavioural observations in the field to study whether in the highly social cichlid Neolamprologus pulcher subordinates participate in reproduction and if so, whether and how this affects their cooperative care, controlling for the effect of kinship. Methodology/Principal Findings We show that: (i) male subordinates gained paternity in 27.8% of all clutches and (ii) if they participated in reproduction, they sired on average 11.8% of young. Subordinate males sharing in reproduction showed more defence against experimentally presented egg predators compared to subordinates not participating in reproduction, and they tended to stay closer to the breeding shelter. No effects of relatedness between subordinates and dominants (to mid-parent, dominant female or dominant male) were detected on parentage and on helping behaviour. Conclusions/Significance This is the first evidence in a cooperatively breeding fish species that the helping effort of male subordinates may depend on obtained paternity, which stresses the need to consider direct fitness benefits in evolutionary studies of helping behaviour.

Electrolyte-free water clearance versus modified electrolyte-free water clearance: do the results justify the effort?

Calculation of electrolyte-free water clearance (EFWC) allows for quantification of renal losses of free water and was shown to be helpful in the differential diagnosis of dysnatremias and might help in the correction of the electrolyte disorders. A modified EFWC formula (MEFWC) was described to be more accurate than the conventional one; however, it has never been evaluated clinically.

[Intensive insulin therapy--is it worth the effort?]

Diabetes mellitus is associated with a number of well-known, specific macro- and microvascular as well as neuropathic complications. The typical and specific association of microvascular and neuropathic complications with diabetes suggests a causal relationship with hyperglycemia or associated metabolic abnormalities. The results of the Diabetes Control and Complications Trial (DCCT) as well as other recent studies have demonstrated that in patients with insulin-dependent diabetes mellitus (IDDM) the incidence of retinopathy, nephropathy and neuropathy can be reduced by intensive treatment. Strategies of intensified insulin therapy and the clinical importance of improved diabetic control are outlined in view of these studies.