We review commonly used population definitions under both the ecological paradigm
(which emphasizes demographic cohesion) and the evolutionary paradigm (which …

The origin of new homoploid species via hybridization is theoretically difficult because it
requires the development of reproductive isolation in sympatry. Nonetheless, this mode is …

Phylogeography is a discipline concerned with various relationships between gene
genealogies—phylogenetics—and geography. The word “phylogeography” was coined in …

A defining feature of species is that their constituting populations are connected by gene
flow. However, interspecific gene flow (introgression) can affect species integrity. If some …

One of the most pervasive challenges in molecular phylogenetics is the incongruence
between phylogenies obtained using different data sets, such as individual genes. To …

The study of reproductive isolation and species barriers frequently focuses on mitochondrial
genomes and has produced two alternative and almost diametrically opposed narratives. On …

Summary 599I. Introduction 599II. Concepts and terminology 600III. Historical background
600IV. Studies of experimental hybrids 6011. Isolating mechanisms 6012. Prezygotic …

The field of systematic biology has been revitalized and transformed during the last few
decades by the confluence of phylogenetic thinking with ready access to the tools of …

Quercus is one of the most abundant and economically important genera of woody plants in
the Northern Hemisphere. To infer phylogenetic relationships within Quercus subgenus …

• Premise of the study: The opuntias (nopales, prickly pears) are not only culturally,
ecologically, economically, and medicinally important, but are renowned for their taxonomic …