This paper analyses the ecological concept of niche that Mayr (1982) adopts in his new, adjusted biological species definition. It is argued here that this concept is part of a typological paradigm still persisting in ecology and thus does not fit the remainder of Mayr's concepts of evolutionary processes based on population thinking. Consequently, adopting this concept in such a definition confuses matters more than it helps. In this analysis particular attention is given to the question of being able to measure niches and populations independently, together with chosing a spatio-temporal scale of variation. Some concepts central to the typological paradigm are also briefly mentioned, together with an alternative approach that could fit better Mayr's population thinking. This alternative approach does not rely on these concepts, nor on a particular choice of scale of variation and allows for the spatio-temporal dynamics of individual species resulting from environmental instability. Thus, it also allows for gradual speciation which the approach using the ecological typological paradigm cannot. Adopting the concept of niche within biological species definitions is not recommended.