Non-independence of individuals in a population of Drosophila melanogaster: effects on spatial distribution and dispersal

We used a simple quadrat analysis to globally categorise the spatial distri bution of Drosophila melanogaster individuals. Individuals were spatially a ggregated and this was not only due to sexual attraction. Th is aggregation seemed to be maintained during dispersal, hence explaining the great varia bility of this behaviour observed in our work and by other authors. Thus, i ndividuals are expected to arrive as small groups into a new patch. This ma y induce costs through competition and benefits by ensuring the presence of reproductive mates and/or if there is a phenomenon of local resource enhan cement by the presence of conspecifics, hence influencing the evolution of dispersal. (C) 2001 Academie des sciences/Editions scientifiques et medical es Elsevier SAS.