Replicated evolutionary inhibition of a complex ancestral behaviour in an adaptive radiation.

Adaptive radiations often exhibit high levels of phenotypic replication, a phenomenon that can be explained by selection on standing variation in repeatedly divergent environments or by the influence of ancestral plasticity on selection in divergent environments. Here, we offer the first evidence that plastic loss of expression of a complex display in a novel environment, followed by selection against expression, could lead to replicated evolutionary inhibition of the phenotype. In both ancestral (oceanic) and benthic (freshwater) populations of the threespine stickleback fish, cannibalism is common and males defending nests respond to approaching groups with a complex diversionary display. This display is not exhibited by males in allopatric, limnetic (freshwater) populations from which cannibalistic groups are absent. Laboratory-reared males from three limnetic populations exhibit a reduced tendency to respond to cannibalistic foraging groups relative to laboratory-reared ancestral and benthic males, but still are capable of producing a similar array of forms of the display despite many generations of disuse. Thus, replication in adaptive radiations can reflect reduced expression of an ancestral trait followed by evolutionary inhibition while the population retains the capacity to express the trait under extreme ancestral conditions.

Adherence to guidelines for prevention of postsplenectomy sepsis. Age and sex are risk factors: a five-year retrospective review.

BACKGROUND: Vaccination, education and use of long-term antibiotics are recommended in expert guidelines for the prevention of infectious complications after splenectomy. However, studies outside Australia have shown poor adherence to the guidelines. METHOD: The aim of this study was to determine overall adherence to the guidelines and to ascertain any independent risk factors for poor compliance with the guidelines. A retrospective review of hospital records between 1999 and 2004 was carried out. RESULTS: Indications for splenectomy of the 111 patients in this review included post-trauma (32), haematological (32), cancer surgery (24), iatrogenic (12) and others (11). On multivariable analysis, age was associated with a 28% less likelihood to receive education (odds ratio (OR) 0.72; 95% confidence interval (CI) 0.56-0.92; P = 0.009) and 36% less likelihood to receive long-term antibiotics (OR 0.64; 95% CI 0.52-0.80; P < or = 0.001). Women were four times more likely to receive education (OR 4.03; 95% CI 1.16-14.0; P = 0.028) and patients who had undergone splenectomy in 2004 were 22 times more likely to have received education compared with those in 1999 (OR 22.53; 95% CI 3.12-162.34; P = 0.002). CONCLUSION: Education for prevention of sepsis after splenectomy is poorly documented and may be incomplete. Older age and male sex are risk factors in non-adherence to guidelines for prevention of postsplenectomy sepsis. Strategies such as alert cards and information brochures may improve adherence to guidelines particularly in older patients.