Intraspecific lineages as focal points in the extinction and persistence of species

Abstract

A deteriorating environment causes species’ range contraction and places species on a trajectory toward rarity and ultimately extinction. Contraction hypotheses focus on the cumulative demise of single populations or groups thereof, without regard to their evolutionary/genetic affinity. I propose that genealogical lineages, be they referred to as subspecies, ecogeographical races, or otherwise, are focal points in the extinction trajectory of species. Such intraspecific entities are likely to be well integrated and respond individualistically to environmental change. Given that these entities have disparate geographical footprints, substantive and varied environmental degradation across a species’ range may cause the demise of intraspecific entities independently of each other. Eventually, all lineages may go extinct and with that the species as a whole. Biodiversity loss has tended to be measured in terms of changes in population and species numbers. The development and implementation of improved conservation policies is contingent upon recognizing the importance of discrete lineages in species survival.