Central to the mode of thought that evolutionary theory opened up is the transition from an understanding of a species as a fixed and eternal "kind" to that of something more akin to a historical lineage stretched between a beginning (speciation) and an inevitable end (extinction). In this context, a species must be understood as something like a "line of movement" through evolutionary time. But it is much more than an empty trajectory. Each species lineage embodies a particular way of life, a particular set of morphological and behavioral characteristics that are passed between generations. But this is also not a static
way of life. More than the sum of those individuals currently living, species are engaged in an ongoing intergenerational process of
becoming – of adaptation and transformation – in which individual organisms are not so much "members" of a class or a kind, but "participants" in an ongoing and evolving way of life.
Thom van Dooren, Flight Ways (Columbia University Press, 2016) p. 27