Table Of ContentOpusc. Zool. Budapest, 2018, 49(1): 33–70
Unified phylogenetic species concept: taking subspecies and race out
of science: postmodern theory applied to the Potamophylax
cingulatus group (Trichoptera, Limnephilidae)
J. OLÁH1, T. ANDERSEN2, S. BESHKOV3, C. CIUBUC4, G. COPPA5, H. IBRAHIMI6, T. KOVÁCS7,
J. OLÁH8 JR. & B. SZCZESNY9
1János Oláh, Residence postal address: Tarján u. 28, H-4032 Debrecen, Hungary. E-mail: [email protected]
2Trond Andersen, Department of Natural History, University Museum of Bergen, University of Bergen, P.O. Box
7800, N-5020 Bergen, Norway. E-mail: [email protected]
3Stoyan Beshkov, National Museum of Natural History, 1 Tsar Osvoboditel Blvd. 1000 Sofia, Bulgaria.
E-mail: [email protected]
4Constantin Ciubuc, Sinaia Zoological Research Station, University of Bucharest, Cumpatu 5, Sinaia, R-106100,
Romania. E-mail: [email protected]
5Gennaro Coppa, 1, rue du Courlis, F-08350 Villers-sur-Bar, France. E-mail: [email protected]
6Halil Ibrahimi, University of Prishtina, Faculty of Mathematics and Natural Sciences, Department of Biology,
Mother Teresa p.n., 10000 Prishtina, Kosovo. E-mail: [email protected]
7Tibor Kovács, HNHM Mátra Museum, Kossuth Lajos u. 40, H-3200 Gyöngyös, Hungar. [email protected]
8János Oláh jr., Residence postal address: Tarján u. 6, H-4032 Debrecen, Hungary.
E-mail: [email protected]
9Bronislaw Szczesny, Institute of Nature Conservation, Polish Academy of Sciences, Kraków, Poland.
E-mail: [email protected]
Abstract. The subspecies of the biological species concept with incomplete reproductive isolation versus the incipient sibling
species of the phylogenetic species concept with permeable reproductive barrier are still applied side by side in the everyday
practice of taxonomy. Both terms refer to the same organisms diverged mostly in allopatry with various stages of repro-
ductive isolation. Question remained: how human ranks these entities organised by nature? The reliable ranking of living
hierarchies is retarded and even obscured by the suppressed state of taxonomy. Disappointing scenario: the science of
biodiversity is stuck in century old macromorphologies without innovation of fine phenomics and without exploring its high-
tech and high-throughput potential. The empirical science of taxonomy is “modernised” by the neutral DNA marker industry
diverting the epistemological focus from empirical to virtual. Virtuality of noumenon is used to camouflage the phenomenon
of the adverse environmental processes, the wasteful byproducts of the profit oriented liberalized economy. The sensual
reality of species and the accelerated species extinction is effectively masked by the virtual sciences of the abstract: numbers,
data, statistics, algorithms, equations, models and ideas. To understand the birth of a young incipient species we have briefly
reviewed the postmodern development of the unified phylogenetic species concept. (1) The reality of species and higher
phylogenetic taxa. (2) The biological and phylogenetic species. (3) How to delineate phylogenetic species? (4) The infinite
versus finite division of phylogenetic species. (5) The construct of the unified species concept. (6) Taking subspecies and
race out of science. Without recognition of incipient siblings of the phylogenetic species the biodiversity remains under-
estimated and the pharisaic anti-science ranking of humans remains with us. The discovery of speciation trait that is the
sexual adaptive structures in reproductive barrier building, which are detectable by fine phenomics, gives perspective to find
the finite division, the dynamic initial split in the continuous process of diversification. The speciation traits produced by
integrative organisation, as opposed to competitive selection, help to unify the operational criteria of the biological species
concept that is the speciation by reproductive isolation with the general concept of phylogenetic species that is the causal
process of the separately evolving metapopulation lineages. The subspecies and racial ranking is untenable anymore, we
suggest taking subspecies and race out of science: the finite division of the initial split detected by speciation traits is the birth
of the phylogenetic incipient sibling species. There is no “subspecies”and “races”, as there is no “subindividual” in the
biological organisation. In the present caddisfly taxonomy the subspecies remained as a valid status in the Potamophylax
_______________________________________________________________________________________________________
urn: lsid:zoobank.org:pub:90FAEE62-9305-4DC6-A372-7A16EB3C2A5A published: 27 June 2018
HU ISSN 2063-1588 (online), HU ISSN 0237-5419 (print) http://dx.doi.org/10.18348/opzool.2018.1.33
Oláh et al.: Unified phylogenetic species concept applied to the Potamophylax cingulatus species group
cingulatus caddisfly species group. With a clear distinction between the neutral and adaptive traits in the P. cingulatus
species group and applying the subtle and stable shape divergences in phallic fine structures we have proposed to change the
taxonomic status of subspecies to incipient sibling phylogenetic species rank: Potamophylax alpinus stat. nov., P. depilis stat
nov., P. ibericus stat. nov., P. inermis stat. nov., reinstated the species status of P. cingulatus stat. restit. and we have
described three new species: P. fesus Oláh, P. portugalicus Oláh et Szczesny, and P. transalpinus Oláh & Coppa, spp. nov.
Keywords. Suppressed taxonomy, speciation trait, race, subspecies, phylogenetic species, sibling species, Potamophylax
cingulatus species group, new species.
INTRODUCTION to, or even exceed the quality of many of our
present-day drawings and structural understand-
Ta xonomy is staggering today in postdarwi- ings. This stagnant condition in taxonomy was
nian contradictions remained non-harmonised created and maintained by non-taxonomists and
as regards the ever-lasting conflict between epis- by distracting movements. In the last eighty years
temology of ranking and ontology of organi- the “modernization” of taxonomy was focused by
sational hierarchies: that is (1) how human ranks highly speculative models of mathematicians
entities and (2) how entities are organised in na- (Haldane, Fischer, and Wright) and by virtual
ture. What are species, subspecies or races as molecular approaches manifested in neutral DNA
organised by nature and as ranked by science? In sequences of geneticists (Dobzhansky). Virtual
spite of these indispensable questions waiting to artefacts of speciation processes, taxon ranking
be understood, our taxonomy that is the basic and species delineations are further deformed by
empirical and integrative discipline of natural his- dictates of ideological and political projects gene-
tory for answering such questions appears more rated in the dominating practices of Darwinism.
and more as a neglected and almost dying science. This kind of “modernization” is getting more
Why taxonomy is suppressed? Is there any cul- transparent today as an intentional movement to
tural interest or social context not to answer these replace and to divert the focus from empirical to
questions, especially the last one: what are races? virtual. Virtuality of noumenon (thing-in-itself,
This happens in the middle of the biodiversity cri- Kant’s Ding an sich) is always flexible enough,
sis amplified by global warming. Today all the compared to phenomenon, to camouflage the on-
achievements of high-tech and high-throughput going adverse environmental processes, the by-
potential of the fine phenomics, the empirical fu- products of the unlimited and unregulated profit-
ture of taxonomy, is repressed and retarded by the oriented human activities. Nature consumption is
over financed blind neutral DNA marker industry. accelerated by the guiding ideology of the un-
Taxonomists realise their backyard position every leashed economic man in the sensible world of the
day in the western culture: there is no sound ge- living creatures. The sensual reality of accelerated
nuine taxonomic project possible to launch with- extinction is effectively masked by the virtual sci-
out at least one component of the modern slogans ences of the abstract: ideas, numbers, data, statis-
fabricated in masking industries: DNA sequenc- tics, algorithms, equations and models.
ing, warming models or evolutionary theories.
The present taxonomic scenario is disappoint-
Is taxonomy suppressed? ing. Over-discussed questions of nature and natu-
ral hierarchies remained unanswered or even ob-
The painful result of this desperate state is scured in a genuine phylogenetic perspective by
clearly documented by the simple fact that “mo- reams of virtual DNA clades. Answers are misled
dern” taxonomy, at least our caddisfly taxonomy, and manipulated by ideological contexts: what are
is based and practiced primarily on the century species, what are subspecies and what are the
old procedures of macromorphologies. The spe- problematic races? Despite of Darwin’s desperate
cies descriptions and drawings of the Russian sci- trials, the ranking and organisational hierarchies
entist Martynov (1909, 1915) are still comparable remained contradictory. Placing discrete bounda-
34
Oláh et al.: Unified phylogenetic species concept applied to the Potamophylax cingulatus species group
ries on the continuous process of diversification in structures of the phallic organ. Stable shape
the universe has produced endless debate, espe- divergences have been discovered both in the
cially in the human created realms of subspecies aedeagus and the paramere structures and inde-
and races. The product oriented nature-exploitive pendent taxa have been discussed, but the possi-
and competitive western culture has significantly bility of species polymorphism was considered at
influenced the process-oriented and more nature- least by a question mark (Szczesny 1990). High
cooperative eastern cultures and getting world- polymorphism was suggested again, but not docu-
wide dominance by globalization. Destroying na- mented in a recent study (Martinez et al. 2016),
ture resources and ecological services are emerg- and the historical polymorphism being a sympat-
ing symptoms of modern western ideology. These ric phenomenon has been debated in the Potamo-
simple symptoms are distracted by “green” move- phylax genus (Oláh 2017). In a detailed study on
ments to such euphemistic slogans like “ecolo- the fine structure of the aedeagus and the para-
gical footprint” in order to camouflage the ideolo- meres the polymorphism was not supported and
gical reality of consumption-idiotism behind: why the shape divergences exhibiting high stability as
/how we accelerate the rate of nature consump- well as coupled with allopatry permitted to deli-
tion. During this permanent “progress” most re- neate and to describe several new subspecies in
sources have been removed from the taxonomy, the Potamophylax cingulatus group (Moretti et al.
from the only integrative science to answer direct- 1994).
ly and openly these questions. Funds are chan-
nelled and disposed either to genetics or to the The discovery of the selective/adaptive specia-
social projects of evolution. As a result, our taxo- tion trait (Oláh et al. 2015, 2017) has initiated
nomy remained mostly stuck in the century old concentrated research first (1) on the fine struc-
pathway of macromorphology and intentionally ture and function of the caddisfly intromittent or-
unarmed by the lack of modern revisions, syn- gan as well as (2) on the structural organisation of
opses and monographs. periphallic organs, especially the paraproct. A-
mong the periphallic organs the paraproct (inter-
mediate appendages) is the structure more inti-
Taxonomic state in the Potamophylax
mately involved in the cryptic female choice du-
cingulatus species group
ring the copulation processes. These selective
traits proved to be sensitive enough to detect early
No progress has yet been realised in the taxo-
stages of reproductive isolation serving the func-
nomic application of the empirical resources of
tion of reproductive barriers delimiting incipient
the fine phenomics. This huge innovative poten-
species of the unified phylogenetic species con-
tial of taxonomy has been left without human and
cept.
financial resources. Its intrinsic and innate empi-
rical nature is almost suppressed by the piles of
In this paper (1) we review briefly how the
virtual neutral molecular markers. But science has
unified phylogenetic species concept has been e-
self-generating innovative power acting even in
volved; (2) how to take subspecies and race out of
such a neglected discipline like taxonomy as has
science; (3) how it is applicable to the taxonomy
been presented by Szczesny (1990) and Moretti et
of the Potamophylax cingulatus species group;
al. (1994).
and (4) why the previously supposed poly-
morphism and the still existing taxonomic rank
Here we sample and apply some theoretical subspecies (or race) in reality represent indepen-
achievements of the phylogenetic species concept dent incipient sibling species. However, based on
to a particular creatures of caddisflies with un- our theoretical considerations (Oláh et al. 2017)
settled taxonomy. One of the initial fine phenomic our first motivation was to examine and to convert
approaches to caddisfly taxonomy was realised in the subspecies status, still unsettled in the
the Potamophylax cingulatus species group by stenophylacini tribe, to phylogenetic sibling spe-
comprehensive comparative studies on the fine cies status in this caddisfly group.
35
Oláh et al.: Unified phylogenetic species concept applied to the Potamophylax cingulatus species group
THEORETICAL PART along the branches? How entities can be discrete
and still transform over time? These difficulties
Species concepts can be alleviated if species are defined in terms of
evolutionary process, as a product of evolutionary
Contemporary systematics is getting to refor- phenomena incorporating small genetic changes
mulate the taxonomic practices by a demanding and the mechanism of natural selection (Cracraft
perspective to delimit and to describe taxa based 1987) or rather an alternative idea of integrative
on phylogenetic history. Yet, non-phylogenetic organisation (Oláh et al. 2017).
and non-history based species concepts, like the
biological species concept, still remains popular. Species is not real. The old linear view of
Species concepts should not conflict with evoluti- species evolution driven by mutations, recombi-
onary history, but often do. Therefore, it is nation and selective pressure and producing a
reasonable to argue for the necessity of a phy- distinct product of species is slowly replaced by a
logenetic species concept (Velasco 2008). Species more complex reality of species differentiating,
is a confusing homonym with three meanings: (1) diverging, merging and reverting while driven by
name of a taxonomic rank (a level or rank in Lin- diverse integrative mechanism against external
naean hierarchy, a taxonomic category); (2) word and internal impacts. As a result, most of the
to a particular taxon of that rank, (ontological species categorization applied by taxonomists is
category, different kinds or ways of being); (3) inherently and obligatory arbitrary (Hunter 2006).
word to the concept of an evolving group of
organisms. This ambiguity is disparate onto- Many believe that species rank does not exist;
logically, but related semantically (Hey et al. it is not a real category in nature. Darwin doubted
2003). Confusion arises often between the species the distinction between species and varieties
as taxa, (groups of organisms with shared set of thinking that species is indefinable in spite of the
traits) and the species as evolving group of closely title of his book “Origin of Species”. Despite
and multiple related individuals. scepticism over the species category, there are
pragmatic reasons for keeping the word species:
Species concepts serve two disciplines: taxo- the species taxa that are the groups of organisms
nomy and evolutionary theory (Cracraft 1987). are real (Ereshefsky 2010). Many genetic studies
Accordingly the term species has two basic have re-examined taxonomies of various groups
functions: (1) the species category as a rank in the of organisms based on morphology and frequently
Linnaean hierarchy created by taxonomist for uncovered paraphyletic or polyphyletic groupings,
grouping organisms and (2) the species as taxa confirming or refuting previous interpretations.
with a location in space and time and referring to Studies on mitochondrial DNA diversity conclud-
objective, observable entities, to living objects ed that mtDNA data and traditional morphological
perceptible by touch (Mayr 1996). Species are taxonomic assignments tend to converge (Avise &
dynamic, evolving individuals, almost like a Walker 1999). The same data have been revisited
quantum systems but human attempts to force with an opposite conclusion (Hendry et al. 2000):
them into rigid classes. Species are real evolu- the mtDNA discontinuities do not match recog-
tionary groups as well as the human-made cate- nised taxonomic species. Species realities have
gories created by subjectively perceived distinc- been questioned, species category abandoned and
tion. The neo-Darwinian synthesis treated the new descriptive scheme was suggested for group-
biological species ambiguously as real or subjec- ing organisms by specifying the amount of diffe-
tively delimited, discrete or nondiscrete, irre- rences in various traits at any levels of the phylo-
ducible or decomposable into smaller units de- genetic tree of life. This conclusion was inde-
pending on particular groups of organisms. How pendent of the marker types used to identify
to maintain the unity and discreteness of species discontinuities. It was interpreted by fundamental
in the Darwinian evolutionary transformations flaws in the species paradigm. Today it is clear
36
Oláh et al.: Unified phylogenetic species concept applied to the Potamophylax cingulatus species group
that expectation to find any direct correspondence nature of taxonomy. Literally suggesting that “an
between neutral markers and adaptive phenomic increase in the scientific staffs of the museums is
splits is a naïve unfounded reductionist trial (Oláh urgently needed if they are to escape from the
et al. 2015). burden of routine description and naming” of
species (Huxley 1940 p. 38). After the new sys-
Only species is real tangible objects. Origi- tematics arrived to replace taxonomy most of the
nally Dobzhansky (1935) has given undisputable available funds moved to genetics in the name of
ontological significance to the biological category taxonomy. The second disaster came to taxonomy
of living individuals. Later (1937), while bringing in the present biodiversity epoch when museums
the Mendelian genetics and the Darwinian evo- are intentionally converted to "baby-sitter centres"
lution together, he has drawn the attention that instead of regaining their real function of collect-
species are the most stable units in taxonomic ing, describing and naming species before their
practice, as compared either with infraspecific extinction. The core mission of taxonomy is to
categories such as variety, race, subspecies, or collect, discover, describe and classify units of
supra-specific ones such as genus, or family. biodiversity, the living companies of the human
During this Modern Synthesis species was treated being.
as fundamentally different entity from taxa of
higher and lower levels in the hierarchy of biolo- All phylogenetic taxa are real tangible objects.
gical organisation. According to this misleading In his phylogenetic systematics Hennig (1950,
concept only the species taxon is the product of 1966) has radically changed this ontological con-
evolution, functioning in a direct way as gene troversy created by the New Systematics of the
pools; exist as whole, as real things (Mayr 1942, Modern Synthesis (Dobzhansky 1937, Huxley
1963). The term species refers to a phenomenon 1940). He has incorporated the role of evolution
of the nature; species are concrete describable in understanding and formulating higher taxa.
objects. Contrary to species, higher or lower taxa Similarly to species the higher level taxa are real,
were viewed as subjective and arbitrary, not as an tangible product of evolution. They exist above
existing real entity (deQueiroz 1985). In the New species level as monophyletic groups composed
Systematics the species definable as distinct self- of the constituting ancestral species, a complete
perpetuating units with an objective existence system of common ancestry, an adequate clade,
have a greater reality in nature, as dynamic evolv- and as the natural outcome of the process of evo-
ing entities that exist independently of human lutionary descent. The only evolutionary signifi-
observer. Species have a greater degree of objec- cant property of higher taxa is whether they com-
tivity, than higher taxonomic categories which are prise this monophyletic clade or not. Genera and
not definable in this concrete way (Huxley 1940). families exist as a whole of complete mono-
This view is still survived repeating that ranking phyletic clades, outside of the mind of taxo-
above or below species level is more subjective nomists (deQueiroz & Donoghue 1988). Higher
and ranks above species are relational, lacking the taxa are real and no any level in the hierarchy is
biological reality of the species (Claridge 2010). biologically more significant than any other. The
weakness of treating species and higher taxa
Besides questioning the reality of higher taxa together is that species boundaries are delimited
along the species tree in the name of modern by theoretically well supported qualitative me-
synthesis, the new systematics has produced more thods, and in contrast, boundaries of higher taxa
severe disaster with long lasting consequences are subjected to quantitative study, and their pat-
culminating today in the biodiversity epoch. Mo- terns is not explained adequately due to lack of
dern Synthesis has started to undermine the sci- theories (Barraclough 2010). Yes, in studies on
ence of taxonomy by giving priority to experi- the evolution of biodiversity the species are the
ments, statistics, ecology and genetics and down- fundamental evolutionary units. From the very
graded the empirical descriptive and comparative beginning of life history studies huge primary
37
Oláh et al.: Unified phylogenetic species concept applied to the Potamophylax cingulatus species group
practical and secondary theoretical data has been segments has produced endless debate and deve-
accumulated in their phenomics by empirical loped multitudes of species concepts (Mayden
comparative observations of qualitative nature. 1997). The essence of the widely accepted biolo-
Qualitative phenomics in taxonomy are self-ex- gical species is the discontinuity created and
planatory, like in fractal languages or in medical maintained by reproductive isolation representing
treatment strategies, including cancer failures and groups of interbreeding natural populations that
cognitive reflections work (Oláh et al. 2015, are reproductively isolated from other such groups
2017) Contrary, higher taxa are intensively stu- (Mayr 1996). The short definition of the biolo-
died mostly quantitatively by algorithms and gical species concept is: “Species are groups of
models as well as by never tested presumptions, interbreeding natural populations that are repro-
thought experiments. ductively isolated from other such groups”.
However, the species criterion of reproductive
Velasco (2008) gave crucial demonstrative isolation is not applicable to the reticulate evo-
role to phylogenetic tree to understand phyloge- lution, to organisms with asexual reproduction as
netic inferences. Trees help to visualize important well as to the classification of fossil organisms.
concepts such as what a monophyletic group is
and how it is constituted by an ancestral and all of The ontology of the biological species concept
its descendants or how two species are recip- is incorrect. It lacks generality, not applicable to
rocally monophyletic having all haplotypes of one asexual organisms and inextensible in time. An
species more closely related to each other than evolutionary analysis demands temporal extensi-
any haplotypes from his sibling and vice versa. bility. The evolutionary phylogenetic species con-
Tree thinking makes easy to understand how cept has been formulated and started to challenge
recency of common ancestry, not morphological the spatial and temporal blindness of the biolo-
(morphological species) or interbreeding (biolo- gical species concept. The naïve full-fledged bio-
gical species) similarity, that defines genealogical logical species concepts of the New Systematics
relationships. Besides giving real tangible exis- and the Modern Synthesis have retarded taxono-
tence to higher taxa on the tree of life, the phylo- my upon the morphologically well separated
genetic systematics has initiated a theoretical architecture of the “adult” biological species with
transformation or rearrangement of the outdated reproductive isolation. The lack of perfect repro-
biological species concept into the phylogenetic ductive isolation is the reason why a subspecies,
species concept. although distinct morphologically, are not a biolo-
gical species. Biological species concept cannot
Biological species concept. Darwin (1859) has be applied to the temporal dimension of species;
replaced the Platonic idea and the Aristotelian unable to specify precisely the limits of species in
typological “form” or “essence” concept of spe- time; not sensitive enough to recognise adequately
cies based on type specimen by the evolutionary the phylogenetic incipient species. Biological spe-
species concept of the lineage segment, “branches cies represent a fixed stage of evolutionary diver-
in the lines of descent”. However, the old tradition gence; a stage in the evolutionary stream where
of species category remained intact functioning interbreeding groups of individuals became segre-
further as a rank in the taxonomic hierarchy and gated and split into two or more groups incapable
predetermined a species concept with fixed tem- to interbreed (Dobzhansky 1937). Large geogra-
poral and spatial stage, an adult stage at the phically subdivided populations or polytypic bio-
artificial time-slices of lineages instead of dyna- logical species often comprising multiple evolu-
mic lineage or branch along the line of descent. tionary entities with or without evolutionary cohe-
Challenged by the spreading ideas of the phylo- sive interbreeding. These entities are inherently
genetic systematics the discrete boundaries of the ambiguous, difficult to demarcate clearly even
“adult” biological species on the continuous pro- with intensive field research and applying pro-
cess of diversification along branches of lineage babilistic threshold with the classic “75% rule”.
38
Oláh et al.: Unified phylogenetic species concept applied to the Potamophylax cingulatus species group
Biological species and its focus on reproduc- because polymorphic variants, clinal variations,
tive isolation is a product of the Modern Syn- forms, geographic races, subspecies, con-species,
thesis, but in fact conflicts with much of the cur- incipient species and “good” species formed a
rent evolutionary thought and distorts history. continuum, the “branches in the lines of descent”
Reproductively isolated groups might be non- (Mallet 2007).
monophyletic and creating problems in phylo-
genetic tree building in diferent ways (Velasco The phylogenetic species. Species are irredu-
2008). (1) Paraphyly problem: biospecies can be
cible discrete groups of countable individuals with
paraphyletic composed of some, but not all, of the
reproductive cohesion (not disjunction) delineated
descendants of some ancestral population; there
by heritable diagnostic characters through space
are two populations, one than splits, one of the
and time and exposed to patterns and processes of
splitted lineages becomes reproductively isolated
evolution along the branches in the line of
from all the others. (2) No tree problem: further
descent. The phylogenetic species is the smallest
speciation events within this paraphyletic bio-
irreducible, but diagnosable monophyletic group
species makes real tree building nonsensical. (3)
of individual organisms; the smallest set of line-
Wrong tree problem: further speciation events
ages descended from a common ancestor possess-
within this paraphyletic biospecies produces
wrong tree. The history of reproductive isolation, ing derived, apomorphic traits with unique evolu-
ecological divergence or morphological diver- tionary history that is with parental pattern of
gence of speciation events does not define evolu- ancestry and descent (Cracraft 1987). Phylogene-
tionary history. tic species concept is typological in the sense that
it is relying upon diagnostic characters in deline-
The widespread and dominating biological ation. In the phylogenetic species concept the evo-
species concept (Mayr 1942) is not in accordance lutionary relationships dominates over fertility,
with the new findings that reproductive barriers contrary to the groups of reproductively isolated
are semipermeable to gene flow and species can interbreeding populations of the biological species
differentiate despite on-going interbreeding concept. If species splitting has not yet reached
(Hausdorf 2011). Biological species concept diagnosability or reproductive cohesion the clus-
lumps well differentiated species that nevertheless ter of species is in statu nascendi (Dozhansky &
interbreed regularly. In the unified phylogenetic Spassky 1959). To rely on reproductive cohesion
species concept the species category is being instead of disjunction is rather reasonable since
decoupled from the hierarchy of taxonomic ranks species and individuals of different higher taxa
and transferred to the hierarchy of biological are frequently interbreeding. Grizzly and polar
organisation (deQueiroz 2011). In the old con- bear breed in nature (Mallet 2008) and intergene-
cepts the species as a rank was accepted only if its ric hybrids are well documented among fishes
lineage had reached a particular stage in the pro- (Burkhead et al. 1991, Garrett 2005), snakes
cess of divergence. Externally allopatric or intrin-
(LeClere et al. 2012) birds (Graves & Zus, 1990,
sically (internally) isolated sympatric (functional
Graves 2007), and primates (Jolly et al. 1997).
allopatry) populations may show every degree of
Interbreeding of closely related sibling species
divergence up to that of “full” species (Wilson &
seems to be a general phenomenon in speciation
Brown 1953). Lineages that had not yet reached
processes induced along secondary contact zones.
that stage were ranked as subspecies, semi-species
Interbreeding is rather a rule and not a coi-
or named whatever, like form, variety or race.
ncidence or exception, under the control of repro-
Biological species are not comparable entities.
ductive cohesion and corrected by reinforcement
The polytypic species contain a variable number
and character displacement.
of subspecies, well differentiated evolutionary
units or arbitrary subdivisions of continuous spa-
tial variation others include only one monotypic In our taxonomic modal analysis on caddisflies
species. For Darwin the distinction along the the entity of phylogenetic species diverged or di-
lineages, lumping or splitting, was unimportant, verging by fine structures of the reproductive
39
Oláh et al.: Unified phylogenetic species concept applied to the Potamophylax cingulatus species group
barriers, defined by specific initial split criterion, dary species criteria, the operational species cri-
and detected by the degree of morphological dif- teria, those no longer considered relevant to spe-
ference as an indication of the underlying degree cies conceptualization but only to species delimi-
of reproductive isolation. The phylogenetic inci- tation that is to assess lineage separation: (1)
pient species is recognised by the diagnostic cha- intrinsic reproductive isolation, (2) diagnosability,
racters of speciation traits. This is the structure (3) monophyly (Queiroz 2007a, b). Most contem-
representing reproductive barrier of the biological porary species concepts are consistent with the
species concept as well as manifesting potential idea that species are evolving lineages or evolving
negative fitness effects in copulating processes. In populations. Taxonomic uncertainty is rooted in
this way the phylogenetic incipient species con- the evolutionary nature of species; therefore it is
cept focuses on the earliest stages of speciation. unlikely to be solved completely by standardiza-
Adaptive speciation trait to separate and describe tion (Isaac et al. 2004). Many diverging orga-
species has been successfully applied recently in nisms are still able to mate and produce viable
detecting, delineating and describing over two offspring, frequently in contact zones. Changing
hundred caddisfly siblings (Oláh et al. 2012, environment may accelerate divergences on eco-
2015, 2017, Oláh & Oláh 2017), combining in logical time scales of hundreds or a few thousands
practice the essence of the phylogenetic and bio- of years reinforced by character displacement,
logical species concepts: initial split by repro- reaching a point of no return. Contrary there are
ductive isolation. convincing cases for reverse speciation where
lineages seemed to converge again; with an in-
How to delineate phylogenetic species? There creasing number of hybrids speciation may go
is inherent subjectivity in all kind of species deli- into a reverse, reaching a point of separation
neation, like in any kind of entity delineation reunite (Hunter 2006).
down to quantum level. In most research fields,
but particularly in quantum physics and in human
An epistemological problem remains however,
behavioural research the observation has a direct
how to delineate species in space and time along
effect on the outcomes (Hey et al. 2003). Under-
these continuously changing lineages? It might be
standing reality is limited by the capacities of
very difficult to assess empirically a particular
observer, by his mental processes and influenced
taxon. Taxonomist’s tools, circumstances, includ-
by his interest. Every cogniser has a different
ing sensual and mental capacities and personal
relative being of anything. Even the “absolute
interest influence the weight to be given to neutral
beings” could be observed from infinity of
or adaptive traits and to their particular pattern of
Nietzsche’s perspectives and could be described
by infinity of potential properties or aspects (Oláh variation in designating and describing new spe-
et al. 2017). Similarly debated is the role of taxo- cies taxa. Taxonomic entities are evolutionary and
nomists playing in the creation of species taxa by demographically dynamic, often not very distinct
taxonomic rank designation. and can change over time or regularly in contact
zones (Hey et al. 2003). Moreover, boundaries of
Species delimitation is frequently confused all entities are sharp or fuzzy depending upon the
with species conceptualization. This results in spatial and temporal scales of detection that is on
controversy concerning definition of species cate- the spatiotemporal point of view of the observer
gory and the methods to detect species bounda- (Cracaft 1987). Species, genera and families
ries. The primary species criterion of the sepa- represent different nested monophyletic clades
rately evolving metapopulation lineage is widely with temporal scales of separations. They are
accepted for species conceptualization. According tangible taxa integrated on population level in the
to this general lineage species concept species are groups of individuals inside of these nested
segments of population-level lineages. There is monophyletic clades and along the time course of
however disagreement about the various secon- phylogenetic divergences.
40
Oláh et al.: Unified phylogenetic species concept applied to the Potamophylax cingulatus species group
How to establish fixed stages for any taxa in assumption incorporated in all algorithms and mo-
the dynamic evolutionary stream of processes dels of phylogenetic reconstruction, both by DNA
permanently working over incipient species, ma- sequences and by unrooted phenetics of numerical
ture species, or incipient genera? Taxonomist’s taxonomy, that divergence (splitting the lineages)
question is what criteria help to identify species occurs in nature, not reticulation (melding of line-
taxa? Evolutionist’s question is what criteria aid
ages). But in nature reticulation (the bête noir for
best to discover locations, boundaries and proper-
cladistics) dominates over divergence and integ-
ties of evolutionary entities? Finding initial split
ration over selection according to the general or-
criteria of the phylogenetic species concept may
ganisational system: aggregates of element in
help to answer both questions. Discovering initial
interaction (Botnariuc 1967). Both the reticulation
split helps to draw the lines of demarcation among
and divergence, like the nature itself, are or-
evolving entities. The essence of the phylogenetic
ganised in fractal pattern occurring in the largest
species delineation is to recognise the first empi-
and in the smallest, irreducible cladistics units.
rical (and/or genomic) sign of the early stages of
Fractal is the nature‘s geometry and organises
reproductive barrier building in reproductive co-
hesion (not disjunction!). Due to ephemeral stages itself by the negentropy of integration, reticulation
of the continuous process of differentiation and against the entropy of disintegration, divergence
the lack of widely accepted easy or obvious and selection. Introgression type of reticulation,
thresholds indicating when speciation has been by melding of lineages, tends to generate
completed, that is an oversimplified detection of phylogenetic discordance more effectively among
initial splits is troublesome (Winker 2010). closely related groups of species, unlike lateral
gene transfer. The amount of gene flow by intro-
The problem of possible infinite division. Final gression and reticulation of hybridisation is vastly
argument against the phylogenetic species con- underestimated (Mallet et al. 2015).
cept refers to the theoretical and practical possi-
bility of the infinitely fine divisions for initial Finite division by speciation super traits. The
splits to differentiate among diverging groups of common vernacular argument against phyloge-
reproductive cohesion. With whole-genome ana- netic species is that every single organism is
lyses any two individuals become diagnosably genetically and phenetically unique. Yes, like eve-
different and could be supported by different ry quantum in the Universe! No, because like
monophyly. Character/gene trees and organismal every quantum, while trying to integrate itself to
trees are controversial and contradictory: taxa can maintain its integer state, is transformed finally
be monophyletic for one character and non-mono- into new emergent entity of natural kind powered
phyletic for another and cladograms are really by the organising forces of integration (Oláh et al.
“cloudograms” superimposed by lineage reticu- 2017), and balancing around an idea expressed as
lation. The testable, therefore objective diagno- nominal kind. Emergence is the appearance of a
sability and monophyly can be found at any level new observable that cannot be derived from the
of hierarchy, but question remains where to draw root theory (Longo et al. 2015). Only reductio-
the lines between lineages? Diagnosability and the nism, like phenetic species concept in taxonomy
smallest cluster depend on the resolution power of and phenetic clade construction in systematics
the character analyses. Diagnosability and believes that a system can be reduced to the sum
reciprocal monophyly, that is the monophyly with of its part. In organizational systemic hierarchy
respect to each other, could be produced by diversification is based on emergence of new enti-
extinction of intermediate forms (Zachos & ties and the emergent properties differ from those
Lovari 2013). With enough traits all individuals of the constituent subunits (Botnariuc 1967).
are diagnosable from each other. Similarly, species as emergent entities are not
divisible infinitely into smaller units. Several pro-
The apparently infinite division is further sup- tective mechanisms evolved in time to produce
ported as well as distracted by the reductionist stable emergencies and to defend their produced
41
Oláh et al.: Unified phylogenetic species concept applied to the Potamophylax cingulatus species group
integrity. Species level organisational emergency Initial split of diverging species could be
cannot be subdivided further if the produced recognised not only by detecting direct signs of
entities of the initial splits are delineated by adap- reproductive isolation or presenting other phylo-
tive traits of the reproductive barrier. In this case genetic branching events, but simply empirically
the shared derived characters of monophyletic by the rarity of hybrids and intermediates between
clades are the adaptive structure itself which is clusters and species (Mallet et al. 2015). These
creating and maintaining the reproductive isola- adaptive structures of initial splits are the spe-
tion. Further subdivision is highly resisted by ciation super traits frequently detectable only by
selection or sexual integration, and the intro- fine phenomics (Oláh et al. 2017). However, in
gression of hybridization may occur without routine observation the speciation super traits
strongly affecting the genomes. But genomic seem stable and subtle products of adaptive spe-
admixture of reticulation nevertheless is realised ciation processes integrated in allopatric isolation
if the introgressed alleles are established. The and their stability is organised and maintained by
adaptive structures of the initial split are stable several integrative and protective genomic mecha-
and highly protected. nisms (Oláh & Oláh 2017). These protective
mechanisms may create nonlinearity in the effect
The initial split is a symbol for a dynamic of primary gene flow, or in the secondary one
temporal dimension representing the genesis of across contact zones, on the processes of diver-
lineage, the splitting of lineage, the birth of a new gences, especially in the genomic building of
lineage entity. Initial split is recognised by opera- reproductive barriers. This is why even at high
tional criteria of the various species concepts rates, gene flow cannot prevent speciation driven
during the delimitation process of the splitted en- and established by adaptive traits of reproductive
tities. The splitted is a real entity in nature, a phy- barriers.
logenetic, evolutionary lineage. Species are enti-
ties that form lineages or lineage-forming biolo- In delimiting the smallest diagnosable cluster
gical entities (deQueiroz 1999). Split entities are of individual organisms there is focus on phe-
gradually becoming more and more differentiated; notypic evidences setting aside genetic data
reproductively incompatible, ecologically distinct, (Tobias et al. 2010): (1) proper nucleotide data
phenetically distinguishable, diagnosable, and are not yet sufficiently available; (2) what is
reciprocally monophyletic. Depending on the dif- available has no relation to the adaptive structures
ferent contemporary species concept and adopting of initial splits; (3) no widespread agreement on
their different priorities for properties of species how nucleotide data can be used to delimit spe-
delineation, disagreement and conflicts are inevi- cies. Examining larger portion of the genome to
table as well as group specific, how to recognise pinpoint specific genes associated with the
exact temporal splitting of the separately evolving observed phenotypic differences of the initial split
lineage. Species are clusters of organisms passing (Patten 2010) seems not very promising to answer
a threshold of divergence determined by one or the basic questions how to detect initial splits in
several operational criteria. Thresholds for each speciation. There are no well-defined genes, in the
operational criterion should be fixed by experts of sense of the traditional Mendelian term, exist
disciplines under the principle of avoiding over- behind the traits of the initial splits (Oláh et al.
splitting. However, threshold finding should not 2017). There is however, thousands of sequences
be realised by numerical or mathematical evalua- with almost infinite combinations of pleiotropic,
tion systems and neither by putting together un- epistasis and epigenetic mechanisms behind mi-
justified operational criteria, like adaptive shape nor shape divergences. Frequently they are unde-
divergence and neutral DNA markers under the tectable empirically, diagnosable only with virtual
name of multi-source integrative taxonomy geometric morphometrics. It seems that the adap-
(Seifert 2014). tive, therefore stable and subtle shape divergen-
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