The ecological basis of life history variation in marsupials

Our understanding of the diversity of mammalian life histories is based almost exclusively on eutherian mammals, in which the slow-fast continuum persists even after controlling for effects of body size and phylogeny. In this paper, we use modern comparative methods to test the extent to which this eutherian-based framework can be extrapolated to metatherian mammals. First, we examine the pattern of covariation among life history traits, and second, we test for correlations between variation in life history and variation in six candidate ecological variables: type of diet, extent of intraspecific competition, risk of juvenile mortality, diurnal pattern of activity, arboreality, and rainfall pattern. Even when controlling for body size and phylogeny, we observe a slow-fast continuum in metatherian mammals. Some parameters involved are different from those identified by studies of eutherians, but the underlying relationships among longevity, fecundity, and age at maturity persist. We also show that overall variation in a key life history variable, reproductive output (measured by annual reproductive rate and litter size), is significantly related to variation in type of diet, with a foliage-rich diet being associated with low fecundity. This is interesting because, although ecological correlations have been found within some eutherian subgroups, modern comparative approaches have failed to reveal robust ecological correlates of overall life history diversity in eutherians. Copyright ESA. All rights reserved.

Ocular melanoma is not associated with CDKN2A or MC1R variants - a population-based study

Germline variants in the melanocortin 1 receptor gene (MC1R) and the p16 gene (CDKN2A) are associated with an increased risk of cutaneous melanoma. The frequency of these germline variants was examined in a population-based, incident series of 62 ocular melanoma cases and ethnicity-matched population controls. In both cases and controls, 59% of individuals carried at least one MC1R variant and there were no significant differences in the frequency of any of the five most common variants of MC1R. We also found no significant differences between cases and controls in the frequency of any of the four most common variants of CDKN2A, and no melanoma case carried a deleterious germline CDKN2A mutation. Our findings argue against an important predisposing effect of the MC1R and CDKN2A genes for ocular melanoma.