The rate of adaptive evolution, the contribution of selection to genetic changes that increase mean fitness, is determined by the additive genetic variance in individual relative fitness. To date, there are few robust estimates of this parameter for natural populations, and it is therefore unclear whether adaptive evolution can play a meaningful role in short-term population dynamics. We developed and applied quantitative genetic methods to long-term datasets from 19 wild bird and mammal populations and found that, while estimates vary between populations, additive genetic variance in relative fitness is often substantial and, on average, twice that of previous estimates. We show that these rates of contemporary adaptive evolution can affect population dynamics and hence that natural selection has the potential to partly mitigate effects of current environmental change.
This article presents the findings of a research project that aimed to contribute to the social inclusion of people with intellectual disabilities (ID) in the World Wide Web (the Web). The Inclusive New Media Design (INMD) project brought together thirty-oneWeb designers and developers with twenty-nine people with intellectual disabilities to explore the best practice for building Web sites accessible to the ID community. Specifically, the project took accessibility techniques identified in ID accessibility research, and investigated what would (or would not) make it possible for Web professionals to implement them. This article suggests some tentative answers to the question of whether a fully accessible Web can be built, one that includes people with ID. While the article outlines simple steps that can be taken to facilitate accessibility for people at the mild end of the ID spectrum, it also highlights a number of barriers that exist to implementing ID accessibility guidance, most notably the power holders and decision makers with whom Web designers work, who may not share the designers' commitment to accessibility.
The derivation of a reliable, subjective measure of awareness that is not contaminated by observers' response bias is a problem that has long occupied researchers. Kunimoto et al. (2001) proposed a measure of awareness (a') which apparently meets this criterion: a' is derived from confidence ratings and is based on the intuition that confidence should reflect awareness. The aim of this paper is to explore the validity of this measure. Some calculations suggested that, contrary to Kunimoto et al.'s intention, a' can vary as a result of changes in response bias affecting the relative proportions of high- and low-confidence responses. This was not evident in the results of Kunimoto et al.'s original experiments because their method may have artificially 'clamped' observers' response bias close to zero. A predicted consequence of allowing response bias to vary freely is that it can result in a' varying from negative, through zero, to positive values, for a given value of discriminability (d'). We tested whether such variations are likely to occur in practice by employing Kunimoto et al.'s paradigm with various modifications, notably the removal of constraints upon the proportions of low- and high-confidence responses, in a visual discrimination task. As predicted, a' varied with response bias in all participants. Similar results were found when a' was calculated from pre-existing data obtained from a patient with blindsight: a' varied through a range of positive results without approaching zero, which is inconsistent with his well-documented lack of awareness. A second experiment showed how response bias could be manipulated to yield elevated values of a'. On the basis of these findings we conclude that Kunimoto's measure is not as impervious to response bias as was originally assumed.
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