Genetic diversity does not explain variation in extra-pair paternity in multiple populations of a songbird.

Many songbirds are socially monogamous but genetically polyandrous, mating with individuals outside their pair bonds. Extra-pair paternity (EPP) varies within and across species, but reasons for this variation remain unclear. One possible source of variation is population genetic diversity, which has been shown in interspecific meta-analyses to correlate with EPP but which has limited support from intraspecific tests. Using eight populations of the genetically polyandrous red-winged blackbird (Agelaius phoeniceus), including an island population, we investigated whether population-level differences in genetic diversity led to differences in EPP. We first measured genetic diversity over 10 microsatellite loci and found, as predicted, low genetic diversity in the island population. Additional structure analyses with multilocus genotypes and mtDNA showed the island population to be distinct from the continental populations. However, the island population's EPP rate fell in the middle of the continental populations' distribution, whereas the continental populations themselves showed significant variation in EPP. This result suggests that genetic diversity by itself is not a predictor of EPP rate. We discuss reasons for the departure from previous results, including hypotheses for EPP that do not solely implicate female-driven behaviour.

The effects of changing vitamin D levels on anemia in chronic kidney disease patients: a retrospective cohort review.

BACKGROUND: Investigate whether changes in vitamin D levels affected erythropoiesis stimulating agent (ESA) requirements in chronic kidney disease (CKD) patients with anemia. METHODS: A retrospective cohort study of nondialysis-dependent patients with CKD of all stages. Patients were anemic and on ESA with at least 2 documented 25-hydroxylated vitamin D (D25) levels drawn 4 months apart. Patients were grouped based on the change in their D25 levels. The primary end point evaluated was absolute change in the ESA doses needed to maintain target hemoglobin levels between 11 and 12 g/dl. RESULTS: A total of 153 patients met the inclusion criteria for analysis. With the exception of the normal-to-low D25 group, patients showed a trend toward lower ESA doses with time. The low-to-normal vitamin D group showed a significant reduction in dose of 24% (1,415 units, p = 0.025). The normal-to-low group, however, showed a 22% increase in dose of 1,270 units (NS). Levels of Ca, PTH, and iron indexes were similar across all groups. CONCLUSION: Our retrospective cohort study demonstrates an ESA sparing effect in patients with vitamin D deficiency after repletion to normal levels. Conversely, there was a trend toward increased ESA requirements in patients who became vitamin D deficient from a previously normal state.