Both sex allocation and sexual conflict can be modulated by spatial structure. However, how the interplay between the type of dispersal and the scale of competition simultaneously affects these traits in sub‐divided populations is rarely considered. We investigated sex allocation and sexual conflict evolution in meta‐populations of the spider mite Tetranychus urticae evolving under budding (pairing females from the same patch) or random (pairing females from different patches) dispersal and either local (fixed sampling from each subpopulation) or global (sampling as a function of subpopulation productivity) competition. Females evolving under budding dispersal produced less female‐biased offspring sex ratios than those from the random dispersal selection regimes, contradicting theoretical predictions. In contrast, the scale of competition did not strongly affect sex allocation. Offspring sex ratio and female fecundity were unaffected by the number of mates, but female fecundity was highest when their mates evolved under budding dispersal, suggesting these males inflict less harm than those evolving under random dispersal. This work highlights that population structure can impact the evolution of sex allocation and sexual conflict. Moreover, selection on either trait may reciprocally affect the evolution of the other, for example via effects on fecundity.

18Both sex allocation and sexual conflict can be modulated by spatial structure. However, how 19 the interplay between the type of dispersal and the scale of competition simultaneously affects 20 these traits in sub-divided populations is rarely considered. 21We investigated sex allocation and sexual conflict evolution in meta-populations of the spider 22 mite Tetranychus urticae evolving under budding (pairing females from the same patch) or 23 random (pairing females from different patches) dispersal and either local (fixed sampling from 24 each subpopulation) versus global (sampling as a function of subpopulation productivity) 25 competition. 26 27Females evolving under budding dispersal produced less female-biased offspring sex ratios 28 than those from the random dispersal selection regimes, contradicting theoretical predictions. 29In turn, the scale of competition did not have a strong effect on sex allocation. Males evolved 30 under budding dispersal induced less female harm than those exposed to random dispersal, but 31 there was no reduction in female fitness following exposure to multiple mates from either 32 selection regime. 34This work highlights that population structure can impact the evolution of sex allocation and 35 sexual conflict. We also discuss how selection on either trait may reciprocally affect the 36 evolution of the other, for example via effects on fecundity. 37 38 Keywords: local mate competition, hard and soft selection, experimental evolution, budding 39 dispersal, scale of competition, Tetranychus urticae. 40 41 42 Many organisms exist in structured populations, sub-divided into patches, that are linked and 43 shaped by demographic factors such as dispersal. The frequency and type of dispersal can 44 determine whether interactions are more likely to occur among related or unrelated individuals 45