Staffan C. Andersson

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1. Based on carotenoids' antioxidant and pro-vitamin functions, carotenoid pigmentation , particularly in birds, has been hypothesized to honestly advertize condition and health. As antioxidants, carotenoids protect the body from oxidative damage caused by internal or external stressors (e.g. growth, infection and anthropogenic pollution). However, the(More)
In breeding plumage, the African male red-shouldered widowbirds (Euplectes axillaris) are black except for red carotenoid-based epaulets ('shoulder patches'), similar to the well-studied American red-winged blackbirds (Agelaius phoeniceus). To experimentally test the signal function of the red epaulets in male red-shouldered widowbirds, we manipulated(More)
In socially monogamous species, extra-pair paternity can increase the variance in reproductive success and thereby the potential for sexual selection on male ornaments. We studied whether male secondary sexual ornaments are selected through within- and/or extra-pair reproductive success in the blue tit (Parus caeruleus). Male blue tits display a bright blue(More)
Many birds display carotenoid-based ornaments, which are typically considered to be honest indicators of individual health and condition. Experimental work on male red-shouldered widowbirds, Euplectes axillaris, has demonstrated a function of the carotenoid-based epaulettes in male contests and territory acquisition. Using two experiments, we investigated(More)
Oxidative stress has been suggested to create a link between 'good genes' and carotenoid coloration via an allocation conflict between external pigmentation and internal antioxidant functions. However, although carotenoid displays have been extensively investigated, there are no experimental tests of the antioxidant efficiency of carotenoids in vivo. We(More)
The differential allocation hypothesis predicts that parents should adjust their current investment in relation to perceived mate attractiveness if this affects offspring fitness. It should be selectively advantageous to risk more of their future reproductive success by investing heavily in current offspring of high reproductive value but to decrease(More)
1. Ornamental carotenoid coloration is commonly based on several different pigments with different nutritional and metabolic constraints. The identification and quantifica-tion of carotenoid pigments is therefore crucial to the understanding of signal content and signal evolution. 2. In male widowbirds (Euplectes spp.), the striking yellow and red(More)
Under chronic stress, carotenoid-based colouration has often been shown to fade. However, the ecological and physiological mechanisms that govern colouration still remain largely unknown. Colour changes may be directly induced by the stressor (for example through reduced carotenoid intake) or due to the activation of the physiological stress response (PSR,(More)
In many birds, carotenoids have dual functions as irreversible plumage pigments and as physiologically essential vitamins and antioxidants. They must be obtained through the diet and may therefore be a limiting resource, a constraint that is likely to vary with factors such as sex, habitat, and time of year. In the present study, we investigated signs of(More)
Subspecies complexes may provide valuable insights into the early stages of the speciation process. The bluethroat (Luscinia svecica) consists of many morphologically distinct subspecies that differ most strikingly in the ornamental colour pattern of the male throat. We investigated the genetic and phenotypic differentiation in this subspecies complex,(More)