The Origin, Expansion, and Demise of Plant Species : Oxford University Press : 9780195127294 : 0195127293 : 04 May 2000 : Combining insights from observation, experimentation, and theory, The Origin, Expansion, and Demise of Plant Species offers a broad overview of species as dynamic entities that arise, have unique evolutionary histories, and ultimately go extinct. It begins with a review of species concepts and the exposition of a new concept; it then addresses plant speciation, the expansion of species from their narrow centers of origin, intraspecific differentiation, and contact zones between differentiated population systems. Special attention is given to the breakdown of cohesion among populations by reproductive and spatial barriers. Also, the ecological and genetic properties of small populations and fragmented population systems are discussed with a focus on the role of hybridization in the demise of species. It ends with an exploration of the longevity of species and the tem