At the boundaries of species

Abstract

Species is a fundamental concept in the study of living systems, of which, however, different, not always overlapping, definitions are given in different sectors of biology. The theoretical elaboration of the Modern Synthesis developed the ambition of unifying the different definitions in that of biological species, based on the concept of reproductive isolation and formalized in particular by Dobzhansky and Mayr. This definition, which presupposes genetic incommunicability following the speciation process, explicitly refers to the metaphor of the tree of life. However, numerous data collected by research in recent decades cast doubt on the possibility of arriving at a univocal defining criterion of the concept of species.