What, if anything, are species?

169 Pages·2021·7.932 MB·English

by  Brent D. Mishler

What, If Anything, Are Species?
Species and Systematics
Phylogenetic Systematics
Haeckel To Hennig
by Olivier Rieppel
Evolution By Natural Selection
Confidence, Evidence and the Gap
by Michaelis Michael
The Evolution of Phylogenetic Systematics
edited by Andrew Hamilton
Molecular Panbiogeography on the Tropics
by Michael Heads
Beyond Cladistics
edited by David M. Williams and Sandra Knapp
Comparative Biogeography
Discovering and Classifying Bio-Geographical Patterns of a Dynamic Earth
by Lynee R. Parenti and Malte C. Ebach
Species
A History of the Idea
by John S. Wilkins
What Species Mean
Understanding the Units of Biodiversity
by Julia Sigwart
What, if anything, are species?
by Brent D. Mishler
Biological Systematics
by Igor Ya. Pavlinov
For more information about this series, please visit: https://www.crcpress.com/
Species-and-Systematics/book-series/CRCSPEANDSYS
What, If Anything, Are Species?
BRENT D. MISHLER
First edition published 2021
by CRC Press
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and by CRC Press
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Contents
Author Biography ..................................................................................................vii
Chapter 1 Introduction ........................................................................................1
Part I What Should the Species Level
represent within the Current
ranked Codes of Nomenclature?
Chapter 2 The Need for Pluralism Because of Different
Biologies in Different Taxa ................................................................7
Species Concepts: A Case for Pluralism .....................................11
The Morphological, Developmental, and
Phylogenetic Basis of Species Concepts in Bryophytes ...............26
Species and Evolution in Clonal
Organisms – Introduction ..........................................................39
Chapter 3 A Phylogenetic Species Concept ......................................................49
Individuality, Pluralism, and the Phylogenetic
Species Concept .......................................................................54
The Phylogenetic Species Concept (Sensu Mishler
and Theriot): Monophyly, Apomorphy, and
Phylogenetic Species Concepts ..................................................70
Part II What Should Happen to taxa at
the traditional Species Level under
a rankless Code of Nomenclature?
Chapter 4 General Principles of Rankless Classification Extended
to the Species Rank ..........................................................................85
Getting Rid of Species? .............................................................89
Species are not Uniquely Real Biological Entities .......................97
Species and Phylogenetic Nomenclature..................................111
The Hunting of the SNaRC: A Snarky Solution to
the Species Problem ................................................................124
v
vi Contents
Chapter 5 Discussion: What Would the World Be Like without
the Species Rank? ...........................................................................143
Endnotes ...............................................................................................................153
Index ......................................................................................................................157
Author
Brent D. Mishler is Director of the University and Jepson Herbaria and Professor
in the Department of Integrative Biology at the University of California, Berkeley,
where he teaches about island biology, biodiversity, evolution, and phylogenetic
analysis.  His research interests are in the ecology and evolutionary biology of bryo-
phytes (mosses and liverworts), as well as the theory of phylogenetic systematics.  He
has been heavily involved in developing electronic resources to present taxonomic
and distributional information about plants to the public, with applications to con-
servation concerns.  He has most recently been involved in developing new “spatial
phylogenetic” tools for studying biodiversity and endemism using large-scale phy-
logenies and collection data in a geographic and statistical framework.
vii

1 Introduction
I am amazed how often biologists, who pride themselves on being objective scien-
tists and who criticize the shibboleths of religion, react vehemently when anyone
challenges the reality of the rank of species and tries to get rid of binomials. I have
heard it so many times:
“We have always had binomials, there would be chaos without them!”
“We must have species in order to do ecology and conservation!”
“How dare you suggest that we get rid of species; they are real entities in the
hierarchy of life!”
Species are truly the sacred cow of biology. Most biologists start their consid-
eration of species with an a priori assumption that they exist. For example Kunz
(2012), in his book-length treatment entitled “Do Species Exist?”, never provides any
good evidence that they do, he just assumes it. He makes tautological statements like:
“If species did not exist, it would not even be possible to speak of the boundaries
between them.” (p. 12). You could just as easily argue that “if the Tooth Fairy did not
exist it would not even be possible to speak of how much she left under a child’s pil-
low.” Chung (2004) starts out a paper on the educational value of teaching students
controversies over species concepts in biology by flatly taking it as “given that spe-
cies are real,” thus glossing over the most fundamental controversy.
More ink has been spilled on the concept of species than on any other concept in
biology. We never seem to eliminate any species concept; rather the field evolves by one
concept after another being added to the pile. It is too much to hope that another book on
the topic (more ink!) can completely resolve the situation. However, a more modest goal
might be achievable, via explaining why there has been such a diversity of views about
species and following modern ideas of phylogenetic classification to their logical destina-
tion. Perhaps the resolution lies in a different direction than the ever-increasing pile of
species concepts. May be we just need to sweep that pile away! May be all the centuries
of angst have been due to people striving to define something that does not exist!
SUMMARY
This book will show that some of the persistent furor over species is based on real
biology and real differences among organisms. The diversity of views is not seman-
tics, it reflects reality; the units traditionally called species in different organisms
are different kinds of things and there is no way to make them the same. Just like
the rank of genus, the rank of species is applied differently in different cases, in part
because of actual biological differences. There is no way to fix this and make the
ranks comparable across life. Instead, the modern idea of rankless phylogenetic clas-
sification, which is well-established at higher taxonomic levels, needs to be extended
to the traditional species level. Something is indeed comparable about taxa, includ-
ing those named as species, but it is not (and cannot be) their ranks.
1