author={Kevin de Queiroz** and Michael J. Donoghue},
Abstract— A tension has arisen over the primacy of interbreeding versus monophyly in defining the species category. Manifestations of this tension include unnecessary restriction of the concept of monophyly as well as inappropriate attribution of “species” properties, to “higher taxa”, and vice versa. Distinctions between systems (wholes) deriving their existence from different underlying. processes have been obscured by failure to acknowledge different interpretations of the concept of… 

When monophyly is not enough: exclusivity as the key to defining a phylogenetic species concept

It is argued that while a phylogenetic species concept must use exclusivity as a grouping criterion, a variety of ranking criteria are consistent with the requirement that species can be placed on phylogenetic trees.


  • P. VranaW. Wheeler
  • Biology
    Cladistics : the international journal of the Willi Hennig Society
  • 1992
It has become increasingly clear that the role and definition of species in a phylogenetic systematics context must be clarified both in order to ascertain the nature of the entities used in

Phylogenetic Species, Nested Hierarchies, and Character Fixation

It is demonstrated that character fixation in alternative species need not coincide with the achievement of reciprocal monophyly, and some of the more frequently criticized aspects of the PSC are functions of sampling that are no more problematic than for any basic systematic endeavor.

Classes or Individuals? The Paradox of Systematics Revisited

Evolution, evidence, and the role of species concepts in phylogenetics

Three general families of species concepts have been proposed within the field of phylogenetic systematics, each with the goal of identifying the minimal taxa within phylogenetic systems as "species," where species are the minimal elements of hierarchic descent systems.

Species concepts and Speciation: Facts and Fantasies

The identification of the punctuated mode of evolution, an alternative to gradualism, has required renewed focus on the nature of species and among the various modes of speciation, allopatric speciation is the best authenticated.

Evolutionary Phycology: Toward a Macroalgal Species Conceptual Framework

A conceptual framework is proposed to enable phycological researchers and students alike to portray species concepts and speciation processes in macroalgae in a manner consistent with dialogue at the forefront of evolutionary biology.

Phylogenetics and the origin of species.

  • J. AviseK. Wollenberg
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1997
A recent criticism that the biological species concept (BSC) unduly neglects phylogeny is examined under a novel modification of coalescent theory that considers multiple, sex-defined genealogical


The compatibility of the phylogenetic species concept with various biological needs for species and its use at the exclusion of alternative species concepts are discussed.

Species concepts and phylogenetics

The concept of exemplars is used to expand the concept of species-as-individual-organisms into a more generally usable concept, and provides a workable basis on which to proceed with phylogenetic analysis and abasis for that analysis to refute or refine species limits.



Individuality, pluralism, and the phylogenetic species concept

The widespread use of the “biological species concept” is flawed for two reasons: because of a failure to distinguish grouping from ranking criteria and because of an unwarranted emphasis on the importance of interbreeding as a universal causal factor controlling evolutionary diversification.

A Critique of the Biological Species Concept and Recommendations for a Phylogenetic Alternative

The biological concept fails to provide unambiguous criteria for grouping organisms (or for assigning species rank), and as a consequence, biological species may not be monophyletic.

Sex and the emergence of species.

Species Concepts and Speciation Analysis

A new mechanistic taxonomy of speciation is needed before population genetics, which deals with evolutionary mechanisms, can be properly integrated with speciation theory; that is, the various modes of Speciation should be characterized according to the various forces and genetic mechanisms that underly the evolution of isolating barriers.

Units and passages: A view for evolutionary biology and ecology

In this analysis, species and monophyletic taxa cannot be uniquely defined as single units that function in ecological and evolutionary processes.

The Morphological, Developmental, and Phylogenetic Basis of Species Concepts in Bryophytes

This paper examines the theoretical and practical status of species relative to two major issues: the recognition of the importance of epigenetic constraints in evolution and the rise of Hennigian

Systematics and the Darwinian Revolution

It is argued that the delay of the Darwinian Revolution in biological taxonomy has resulted partly from a failure to distinguish between two fundamentally different ways of ordering identified by Griffiths (1974): classification and systematization.

The Ontogenetic Method for Determining Character Polarity and its Relevance to Phylogenetic Systematics

The ontogenetic method for determining character polarity (the biogenetic law of Nelson, 1978) is analyzed from the perspective of phylogenetic systematics, which results in the conclusion that there is no threefold parallelism in phylogenetically systematics.

Species concepts and the ontology of evolution

These ontological and biological difficulties can be alleviated if species are defined in terms of evolutionary units, which are irreducible clusters of reproductively cohesive organisms that are diagnosably distinct from other such clusters.

The Ontological Status of Species as Evolutionary Units

The species problem was of some importance ages ago in the philosophical dispute between nominalists and essentialists or a century ago in biology when Darwin introduced his theory of organic evolution, but it certainly is of no contemporary interest.