Nonadaptive radiation

species flocks) that are characterized by diversification that is not driven by resource partitioning.^[1][2][3][4] The species that are a part of a nonadaptive radiation will tend to have very similar niches, and in many (though not all) cases will be morphologically similar.^[4] Nonadaptive radiations are driven by nonecological speciation.^[2][4] In many cases, this nonecological speciation is allopatric, and the organisms are dispersal-limited such that populations can be geographically isolated within a landscape with relatively similar ecological conditions.^[4] For example, Albinaria land snails on islands in the Mediterranean^[1] and Batrachoseps salamanders from California^[2] each include relatively dispersal-limited, and closely related, ecologically similar species often have minimal range overlap, a pattern consistent with allopatric, nonecological speciation. In other cases, such as certain damselflies^[3] and crickets from Hawaii,^[5] there can be range overlap in closely related species, and it is likely that sexual selection (and species recognition) plays a role in maintaining (and perhaps giving rise to) species boundaries.^[4]