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The costs of mischoosing are not uniform across individuals

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Matching habitat choice is a particular form of habitat selection based on self?assessment of local performance that offers individuals a means to optimize the match of phenotype to the environment. Despite the advantages of this mechanism in terms of increased local adaptation, examples from natural populations are extremely rare. One possible reason for the apparent rarity of matching habitat choice is that it might be manifest only in those segments of a population for which the cost of a phenotype–environment mismatch is high. To test this hypothesis, we used a breeding population of sockeye salmon (Oncorhynchus nerka) exposed to size-dependent predation risk by bears, and evaluated the costs of mischoosing in discrete groups (e.g. male versus females, and ocean?age 2 versus ocean?age 3) using reproductive life span as a measure of individual performance. Bear preference for larger fish, especially in shallow water, translates into a performance trade-off that sockeye salmon can potentially use to guide their settlement decisions. Consistent with matching habitat choice, we found that salmon of similar ocean?age and size tended to cluster together in sites of similar water depth. However, matching habitat choice was only favoured in 3?ocean females – the segment of the population most vulnerable to bear predation. This study illustrates the unequal relevance of matching habitat choice to different segments of a population, and suggests that ‘partial matching habitat choice' could have resulted in an underestimation of the actual prevalence of this mechanism in nature. informacion[at]ebd.csic.es: Camacho & Hendry (2020) Matching habitat choice: it's not for everyone. Oikos DOI 10.1111/oik.06932


https://onlinelibrary.wiley.com/doi/full/10.1111/oik.06932
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Unique evolution of vitamin A as an external pigment in tropical starlings

Unique evolution of vitamin A as an external pigment in tropical starlings

Pigments are largely responsible for the appearance of organisms. Most biological pigments derive from the metabolism of shikimic acid (melanins), mevalonic acid (carotenoids) or levulinic acid (porphyrins), which thus generate the observed diversity of external phenotypes. Starlings are generally dark birds despite iridescence in feathers, but 10 % of species have evolved plumage pigmentation comprising bright colors that are known to be produced only by carotenoids. However, using micro-Raman spectroscopy, it was discovered that the bright yellow plumage coloration of one of these species, the Afrotropical golden-breasted starling Cosmopsarus regius, is not produced by carotenoids, but by vitamin A (all-trans-retinol). This is the first organism reported to deposit significant amounts of vitamin A in its integument and use it as a body pigment. Phylogenetic reconstructions reveal that the retinol-based pigmentation of the golden-breasted starling has independently appeared in the starling family from dark ancestors. This study thus unveils a unique evolution of a new class of external pigments comprised by retinoids. información[at]ebd.csic.es: Galván et al (2019) Unique evolution of vitamin A as an external pigment in tropical starlings. J Exp Biol doi: 10.1242/jeb.205229


http://jeb.biologists.org/content/early/2019/05/16/jeb.205229