Abstract
Non-genetic transmission of information across generations, so-called parentaleffects, can have significant impacts on offspring morphology, physiology,behaviour and life-history traits. In previous experimental work using thetwo-spotted spider miteTetranychus urticaeKoch, we demonstrated that dis-persal distances increase with local density and levels of genetic relatedness.We here show that manipulation of parental and grand-parental density hasa significant effect on offspring dispersal distance, of the same order of magni-tude as manipulation of offspring density. We demonstrate that offspringexposed to the same density disperse further if they were born to parentsexposed to higher density compared with parents exposed to low density.Offspring dispersal distance also increases when grand-parents were exposedto higher density, except for offspring exposed to low densities, which disperseat shorter distances whatever the grand-parental density. We also show thatoffspring from mothers exposed to higher densities were overall larger,which suggests that parents in high densities invest more in individual off-spring, enabling them to disperse further. We propose that our findingsshould be included in models investigating the spread rate of invasive speciesor when predicting the success of conservation measures of species attemptingto track changing climates.