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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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A global synthesis reveals biodiversity-mediated benefits for crop production

A global synthesis reveals biodiversity-mediated benefits for crop production

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield–related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), the relative importance of species richness, abundance, and dominance (relative species abundance) for pollination; biological pest control, and final yields in the context of ongoing land-use change was partitioned. Pollinator and pest natural enemies richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Results confirm that the more intensive agriculture is, the more it reduces life around it. On the contrary, landscapes with mixed crops, with hedges and wasteland show a greater abundance of pollinators and up to 40% more variety of beneficial fauna. One of the many works included in this review deals with the cultivation of oilseed rape on 300 farms in western France. This study showed that crop yields and the gross income of rapeseed were greater (between 15% and 40%) in the areas with greater abundance of pollinators. Larger crops can be obtained by increasing agrochemicals or the abundance of pollinators, but the economic benefits of crops only improve with the latter as pesticides increase production costs. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society. informacion[at] Dainese et al (2019) A global synthesis reveals biodiversity-mediated benefits for crop production. Sci Adv DOI 10.1126/sciadv.aax0121