Given the predicted expansion of cities throughout the world, understanding the effect of urbanization on bee fauna is a major issue for the conservation of bees. The aim of this study was to understand how urbanization affects wild bee assemblages along a gradient of impervious surfaces and to determine the influence of landscape composition and floral resource availability on these assemblages. We chose 12 sites with a proportion of impervious surfaces (soil covered by parking, roads, and buildings) ranging from 0.06% to 64.31% within a 500 m radius. We collected using pan trapping and estimated the landscape composition of the sites within a 500 m radius and the species richness of plant assemblages within a 200 m radius. We collected 1104 bees from 74 species. The proportion of impervious surfaces at the landscape scale had a negative effect on wild bee abundance and species richness, whereas local flower composition had no effect. Ground‐nesting bees were particularly sensitive to the urbanization gradient. This study provides new evidences of the impact of urbanization on bee assemblages and the proportion of impervious surfaces at the landscape scale emerged as a key factor that drives those assemblages.

Rapid life‐history changes caused by size‐selective harvesting are often interpreted as a response to direct harvest selection against a large body size. However, similar trait changes may result from a harvest‐induced relaxation of natural selection for a large body size via density‐dependent selection. Here, we show evidence of such density‐dependent selection favouring large‐bodied individuals at high population densities, in replicated pond populations of medaka fish. Harvesting, in contrast, selected medaka directly against a large body size and, in parallel, decreased medaka population densities. Five years of harvesting were enough for harvested and unharvested medaka populations to inherit the classically predicted trait differences, whereby harvested medaka grew slower and matured earlier than unharvested medaka. We show that this life‐history divergence was not driven by direct harvest selection for a smaller body size in harvested populations, but by density‐dependent natural selection for a larger body size in unharvested populations.

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