Retinal opsin photopigments initiate mammalian vision when stimulated by light. Most mammals possess a short wavelength-sensitive opsin 1 (SWS1) pigment that is primarily sensitive to either ultraviolet or violet light, leading to variation in colour perception across species. Despite knowledge of both ultraviolet-and violet-sensitive SWS1 classes in mammals for 25 years, the adaptive significance of this variation has not been subjected to hypothesis testing, resulting in minimal understanding of the basis for mammalian SWS1 spectral tuning evolution. Here, we gathered data on SWS1 for 403 mammal species, including novel SWS1 sequences for 97 species. Ancestral sequence reconstructions suggest that the most recent common ancestor of Theria possessed an ultraviolet SWS1 pigment, and that violet-sensitive pigments evolved at least 12 times in mammalian history. We also observed that ultraviolet pigments, previously considered to be a rarity, are common in mammals. We then used phylogenetic comparative methods to test the hypotheses that the evolution of violet-sensitive SWS1 is associated with increased light exposure, extended longevity and longer eye length. We discovered that diurnal mammals and species with longer eyes are more likely to have violet-sensitive pigments and less likely to possess UV-sensitive pigments. We hypothesize that (i) as mammals evolved larger body sizes, they evolved longer eyes, which limited transmittance of ultraviolet light to the retina due to an increase in Rayleigh scattering, and (ii) as mammals began to invade diurnal temporal niches, they evolved lenses with low UV transmittance to reduce chromatic aberration and/or photo-oxidative damage.

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In recent years, there are increasingly practitioners and researchers conducting human-computer interaction (HCI) projects that focused on sustainability. In particular, the art of visualization in HCI has been radically utilized to represent statistical numbers or figures of energy consumption, e.g. electricity, to create energy awareness and thus foster positive attitudes towards sustainable practices. However, it seems to be a major issue when users with different concerns and motivations to conserve energy provide a variety of feedback for generic information in research prototypes. To address this issue, several researches and critical surveys have been aiming to explore which factors influence most to users' energy conservation reactions. Based on those surveys, this paper attempts to provide a conclusion of most effective factors and then take advantage of those factors to design a prototype combining Eco-feedback and social media to motivate energy conservation behaviors.