The medical student

The Medical Student was published from 1888-1921 by the students of Boston University School of Medicine

The medical student

The Medical Student was published from 1888-1921 by the students of Boston University School of Medicine

Sexual dimorphism in postcranial skeletal shape suggests male‐biased specialization for physical competition in anthropoid primates

Sexual dimorphism often arises as a response to selection on traits that improve a male's ability to physically compete for access to mates. In primates, sexual dimorphism in body mass and canine size is more common in species with intense male–male competition. However, in addition to these traits, other musculoskeletal adaptations may improve male fighting performance. Postcranial traits that increase strength, agility, and maneuverability may also be under selection. To test the hypothesis that males, as compared to females, are more specialized for physical competition in their postcranial anatomy, we compared sex‐specific skeletal shape using a set of functional indices predicted to improve fighting performance. Across species, we found significant sexual dimorphism in a subset of these indices, indicating the presence of skeletal shape sexual dimorphism in our sample of anthropoid primates. Mean skeletal shape sexual dimorphism was positively correlated with sexual dimorphism in body size, an indicator of the intensity of male–male competition, even when controlling for both body mass and phylogenetic relatedness. These results suggest that selection on male fighting ability has played a role in the evolution of postcranial sexual dimorphism in primates

Lions and Prions and Deer Demise

Background: Contagious prion diseases – scrapie of sheep and chronic wasting disease of several species in the deer family – give rise to epidemics that seem capable of compromising host population viability. Despite this prospect, the ecological consequences of prion disease epidemics in natural populations have received little consideration. Methodology/Principal Findings: Using a cohort study design, we found that prion infection dramatically lowered survival of free-ranging adult (.2-year-old) mule deer (Odocoileus hemionus): estimated average life expectancy was 5.2 additional years for uninfected deer but only 1.6 additional years for infected deer. Prion infection also increased nearly fourfold the rate of mountain lions (Puma concolor) preying on deer, suggesting that epidemics may alter predator–prey dynamics by facilitating hunting success. Despite selective predation, about one fourth of the adult deer we sampled were infected. High prevalence and low survival of infected deer provided a plausible explanation for the marked decline in this deer population since the 1980s. Conclusion: Remarkably high infection rates sustained in the face of intense predation show that even seemingly complete ecosystems may offer little resistance to the spread and persistence of contagious prion diseases. Moreover, the depression of infected populations may lead to local imbalances in food webs and nutrient cycling in ecosystems in which deer ar

Appeals to evidence for the resolution of wicked problems: the origins and mechanisms of evidentiary bias

Wicked policy problems are often said to be characterized by their ‘intractability’, whereby appeals to evidence are unable to provide policy resolution. Advocates for ‘Evidence Based Policy’ (EBP) often lament these situations as representing the misuse of evidence for strategic ends, while critical policy studies authors counter that policy decisions are fundamentally about competing values, with the (blind) embrace of technical evidence depoliticizing political decisions. This paper aims to help resolve these conflicts and, in doing so, consider how to address this particular feature of problem wickedness. Specifically the paper delineates two forms of evidentiary bias that drive intractability, each of which is reflected by contrasting positions in the EBP debates: ‘technical bias’ - referring to invalid uses of evidence; and ‘issue bias’ - referring to how pieces of evidence direct policy agendas to particular concerns. Drawing on the fields of policy studies and cognitive psychology, the paper explores the ways in which competing interests and values manifest in these forms of bias, and shape evidence utilization through different mechanisms. The paper presents a conceptual framework reflecting on how the nature of policy problems in terms of their complexity, contestation, and polarization can help identify the potential origins and mechanisms of evidentiary bias leading to intractability in some wicked policy debates. The discussion reflects on whether being better informed about such mechanisms permit future work that may lead to strategies to mitigate or overcome such intractability in the future

Behavioral genomics of honeybee foraging and nest defense

The honeybee has been the most important insect species for study of social behavior. The recently released draft genomic sequence for the bee will accelerate honeybee behavioral genetics. Although we lack sufficient tools to manipulate this genome easily, quantitative trait loci (QTLs) that influence natural variation in behavior have been identified and tested for their effects on correlated behavioral traits. We review what is known about the genetics and physiology of two behavioral traits in honeybees, foraging specialization (pollen versus nectar), and defensive behavior, and present evidence that map-based cloning of genes is more feasible in the bee than in other metazoans. We also present bioinformatic analyses of candidate genes within QTL confidence intervals (CIs). The high recombination rate of the bee made it possible to narrow the search to regions containing only 17–61 predicted peptides for each QTL, although CIs covered large genetic distances. Knowledge of correlated behavioral traits, comparative bioinformatics, and expression assays facilitated evaluation of candidate genes. An overrepresentation of genes involved in ovarian development and insulin-like signaling components within pollen foraging QTL regions suggests that an ancestral reproductive gene network was co-opted during the evolution of foraging specialization. The major QTL influencing defensive/aggressive behavior contains orthologs of genes involved in central nervous system activity and neurogenesis. Candidates at the other two defensive-behavior QTLs include modulators of sensory signaling (Am5HT(7) serotonin receptor, AmArr4 arrestin, and GABA-B-R1 receptor). These studies are the first step in linking natural variation in honeybee social behavior to the identification of underlying genes