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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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Effects of climate change on sea turtles nesting

Effects of climate change on sea turtles nesting

Sea turtles are vertebrates with temperature-dependent sex determination. Rising temperatures due to climate change cause female-biased sex ratios. Here, the influence of nest depth and shading conditions on nest temperatures and hatchling fitness of the leatherback sea turtle Dermochelys coriacea have been assessed. Forty-eight leatherback clutches were relocated into a hatchery in 2013, 2014 and 2015, respectively. Of these, 24 clutches were placed under shade conditions and 24 were placed under unshaded (sun) conditions at three depths (50, 75, 90 cm). Fitness (as measured by greater carapace length, carapace width and hatchling weight) and locomotion performance (faster crawling and shorter righting responses) were better in leatherback hatchlings from the cooler, shaded nests than in those from the warmer, unshaded nests. In 2013, in clutches at a depth of 50 cm, hatching success was higher for the shaded clutches than for the unshaded clutches, while in clutches at deeper depths unshaded clutches had higher hatching success than shaded clutches. These results show that shaded conditions produced hatchlings with a higher fitness and a higher likelihood of being male. Therefore, results can be used to provide conservation policies with a tool to decrease the current female-skewed sex ratio production caused by rising temperatures at most nesting rookeries around the world. informacion[at] Rivas et al (2019) Potential male leatherback hatchlings exhibit higher fitness which might balance sea turtle sex ratios in the face of climate change. Clim Chang