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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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Macroevolutionary shift in the size of amphibian genomes and the role of life history and climate

Macroevolutionary shift in the size of amphibian genomes and the role of life history and climate

Genome size varies enormously from one species to another, and amphibians are the group of vertebrates where genome size varies the most. Amphibians are also really old lineages that have been evolving for millions of years, diversifying and adapting to highly contrasting environments, from the warm and humid tropics to cold regions at high latitudes or high elevations. Amphibians have also evolved a frenzy of reproductive modes ranging from the well known case of aquatic tadpoles that metamorphose into terrestrial juveniles to direct developers that skip the larval phase and hatch from terrestrial eggs directly as terrestrial juveniles. Comparative phylogenetic analyses were used to test if such a dramatic evolutionary history has had any consequences for the evolution of genome sizes in amphibians. It resulted that amphibian genomes have undergone saltations in size, although these are rare and the evolutionary history of genome size in amphibians has otherwise been one of gradual differentiation. This macroevolutionary homogeneity is remarkable given the evolutionary and ecological diversity of most other aspects of the natural history of amphibians. No evidence was found for associations between life cycle complexity and genome size despite the high diversity of reproductive modes and the multiple events of independent evolution of divergent life cycles in the group. Species with fast development show reduced genome sizes. Also, climate affects genome size indirectly, at least in frogs, as a consequence of its effect on development. informacion[at] Liedtke et al (2018) Macroevolutionary shift in the size of amphibian genomes and the role of life history and climate. Nature Ecol Evol. DOI: 10.1038/s41559-018-0674-4