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The costs of mischoosing are not uniform across individuals


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] Camacho & Hendry (2020) Matching habitat choice: it's not for everyone. Oikos DOI 10.1111/oik.06932
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“Planned obsolescence” in the plumage of larks

"Planned obsolescence" in the plumage of larks

Larks (Alaudidae) present a heavily worn plumage for the most part of the annual cycle, to the point that identification field guides typically depict lark species in both fresh and worn plumages. The ephemeral nature of lark feathers is even more strange knowing that larks are among the few passerines undergoing a single annual molt. Contrarily, a majority of songbirds moult feathers twice a year. Larks are dull-colored ground-dwelling birds living in open areas, thus occupying a niche where abrasion by air and soil particles is maximal. Authors observed that lark feathers have unmelanized fringes and are prone to breakage. Larks may have turned need into a virtue: they possibly cannot avoid a premature damage of their fragile plumage, and instead of incurring the cost of molting repeatedly, they gain the advantage of a form of crypsis known as disruptive camouflage. When feathers break, they create a serrated random pattern, cancelling out the effect of smooth lines more easily detected by predators. informacion[at] Negro et al (2019) Adaptive plumage wear for increased crypsis in the plumage of Palearctic larks (Alaudidae). Ecology