SPATIAL AND TEMPORAL FACTORS AFFECTING COEXISTENCE AMONG SEXUAL AND CLONAL FORMS OF POECILIOPSIS

We examined spatial and seasonal factors affecting coexistence of closely related sexual and asexual fishes of the genus Poeciliopsis living in two ecologically distinct stream habitats. Stream order and productivity influenced frequencies of these fish, and local habitat patchiness contributed strongly to spatial segregation. The magnitude and direction of local segregation was unaffected by striking seasonal variation in one stream. For the second stream, the relative contributions of local, geographical, and seasonal components of spatial variation were assessed through estimation of variance components. Spatial segregation at the smallest scale accounted for the largest proportion of variance in the distribution of species and clones.