scholarly journals Introduction. Speciation in plants and animals: pattern and process

2008 ◽  
Vol 363 (1506) ◽  
pp. 2965-2969 ◽  
Author(s):  
Richard J Abbott ◽  
Michael G Ritchie ◽  
Peter M Hollingsworth

Although approximately 150 years have passed since the publication of On the origin of species by means of natural selection , the definition of what species are and the ways in which species originate remain contentious issues in evolutionary biology. The biological species concept, which defines species as groups of interbreeding natural populations that are reproductively isolated from other such groups, continues to draw support. However, there is a growing realization that many animal and plant species can hybridize with their close relatives and exchange genes without losing their identity. On occasion, such hybridization can lead to the origin of new species. A key to understanding what species are and the ways in which they originate rests to a large extent on a detailed knowledge of the nature and genetics of factors that limit gene flow between species and the conditions under which such isolation originates. The collection of papers in this issue addresses these topics and deals as well with some specific issues of hybrid speciation and the causes of species radiations. The papers included arise from a 1-day symposium on speciation held during the Sixth Biennial Meeting of the Systematics Association at Edinburgh in August 2007. In this introduction, we provide some background to these papers and highlight some key points made. The papers make clear that highly significant advances to our understanding of animal and plant speciation are currently being made across the range of this topic.

2005 ◽  
Vol 176 (2) ◽  
pp. 221-225
Author(s):  
Jean Génermont

Abstract In 1980, Henri Tintant advocated the usefulness of the biological species concept in paleontology. At this time, this concept was still accepted by many neontologists, but it was already rather severely criticized by some others. In fact, a lot of new concepts appeared in the course of the following two decades. While a few ones are mere adjustments of the biological concept, for instance taking in account ecological criteria, in such a way that it could be applied to clonal organisms, some others, which were developed in connexion with the cladistic theory of taxonomy, are truly new from a conceptual point of view. The diagnosable version of the phylogenetic species concept is somewhat reminiscent of Simpson’s evolutionary species concept, since it accepts phyletic speciation as well as survival of the stem species after a cladogenetic event. One of its more criticizable features, from a cladistic point of view, is that the species are not necessarilly monophyletic. On another hand, according to the monophyly version of the phylogenetic species concept, species are recognized rather subjectively as monophyletic taxa revealed by some previous cladistic analysis dealing with operational taxonomic units. A consensus on the definition of species cannot be expected, since all concepts related to the biological one are founded on population grouping on the basis of potentially identical evolutionary fates, while those which are related to cladistic taxonomy are exclusively concerned with historical features.


2020 ◽  
pp. 16-51
Author(s):  
Pavel V. Pfander ◽  
◽  

The main disadvantage of the generally accepted trinary system of around-species nomenclature is the lack of a species concept. This leads to the fact that any lower taxon can be declared a species or subspecies, and any combination of these taxa of arbitrary rank is correct and legitimate, by definition, and therefore cannot even be discussed. Ambiguity of the level of divergence of species creates a “species problem” and makes the question – species or subspecies – meaningless. The solution to the “species problem” can be the creation of a nomenclature system with a "own" species concept. The only concept whose criteria are objective (reproductive isolation and sympatry) and, more importantly, correspond to a certain level of divergence, and that have a biological meaning, is a biological species concept. However, the use of this concept is difficult due to the uncertainty of the degree of reproductive isolation. Therefore, a revised definition of a biological species (B-species) as a category of taxonomy is proposed – this is a level of divergence that provides reproductive isolation sufficient for sympatry (with other closely related forms). Accordingly, as a physical object, the B-species can be defined as a set of sister populations that are incapable to sympatry with each other. The level of B-species is very high, therefore, for forms intermediate between subspecies and B-species, an additional category is needed – a semi-species. Unlike subspecies, which differ only in size and color, a semi-species must have at least one of the following features: 1 – obvious differences in the preference for environmental conditions; 2 – a certain assortative mating with other semi-species; 3 – reduced fertility of hybrids; 4 – significant differences in morphology, physiology, behavior, etc.; 5 – the hybridization zone is relatively very narrow (parapatry). The taxonomy of birds of prey (Falconiformes, Accipitriformes) of Northern Eurasia is presented in a new (genus, B-species, semi-species, subspecies) system of categories and nomenclature.


2018 ◽  
Vol 115 (23) ◽  
pp. 6040-6045 ◽  
Author(s):  
Louis-Marie Bobay ◽  
Howard Ochman

Due to their dependence on cellular organisms for metabolism and replication, viruses are typically named and assigned to species according to their genome structure and the original host that they infect. But because viruses often infect multiple hosts and the numbers of distinct lineages within a host can be vast, their delineation into species is often dictated by arbitrary sequence thresholds, which are highly inconsistent across lineages. Here we apply an approach to determine the boundaries of viral species based on the detection of gene flow within populations, thereby defining viral species according to the biological species concept (BSC). Despite the potential for gene transfer between highly divergent genomes, viruses, like the cellular organisms they infect, assort into reproductively isolated groups and can be organized into biological species. This approach revealed that BSC-defined viral species are often congruent with the taxonomic partitioning based on shared gene contents and host tropism, and that bacteriophages can similarly be classified in biological species. These results open the possibility to use a single, universal definition of species that is applicable across cellular and acellular lifeforms.


Author(s):  
Samir Okasha

‘Species and classification’ first considers the species problem and the biological species concept. It then discusses phylogenetic systematics, which involves the organization of species into higher taxa. Classification in science raises a deep philosophical issue as all objects can in principle be classified in more than one way. Is there a ‘correct’ way to assign organisms to species, and species to higher taxa? Classification of organisms was traditionally done using the Linnaean system, which served biologists well for years, and elements of it are still used today. However, the rise of evolutionary biology has led to fundamental changes in both the theory and practice of biological classification.


2021 ◽  
Vol 102 (4) ◽  
Author(s):  
Yiyuan Li ◽  
Angela C. O’Donnell ◽  
Howard Ochman

Mosquito-borne arboviruses, including a diverse array of alphaviruses and flaviviruses, lead to hundreds of millions of human infections each year. Current methods for species-level classification of arboviruses adhere to guidelines prescribed by the International Committee on Taxonomy of Viruses (ICTV), and generally apply a polyphasic approach that might include information about viral vectors, hosts, geographical distribution, antigenicity, levels of DNA similarity, disease association and/or ecological characteristics. However, there is substantial variation in the criteria used to define viral species, which can lead to the establishment of artificial boundaries between species and inconsistencies when inferring their relatedness, variation and evolutionary history. In this study, we apply a single, uniform principle – that underlying the Biological Species Concept (BSC) – to define biological species of arboviruses based on recombination between genomes. Given that few recombination events have been documented in arboviruses, we investigate the incidence of recombination within and among major arboviral groups using an approach based on the ratio of homoplastic sites (recombinant alleles) to non-homoplastic sites (vertically transmitted alleles). This approach supports many ICTV-designations but also recognizes several cases in which a named species comprises multiple biological species. These findings demonstrate that this metric may be applied to all lifeforms, including viruses, and lead to more consistent and accurate delineation of viral species.


PLoS ONE ◽  
2013 ◽  
Vol 8 (6) ◽  
pp. e68267 ◽  
Author(s):  
Lélia Lagache ◽  
Jean-Benoist Leger ◽  
Jean-Jacques Daudin ◽  
Rémy J. Petit ◽  
Corinne Vacher

Phytotaxa ◽  
2020 ◽  
Vol 455 (4) ◽  
pp. 262-266
Author(s):  
LIANG ZHANG ◽  
LI-BING ZHANG

The biological species concept is not exclusively applicable in many groups of organisms including ferns. Interspecific fern hybrids are not rare: there are 16 intergeneric hybrid genera in ferns confirmed with molecular data. Here we add one more hybrid genus in the tribe Lepisoreae of Polypodiaceae, ×Lepinema, formed via hybridization between parents in two genera: Ellipinema and Lepisorus.


2010 ◽  
Vol 365 (1547) ◽  
pp. 1853-1863 ◽  
Author(s):  
James Mallet

The development of what became known as the biological species concept began with a paper by Theodosius Dobzhansky in 1935, and was amplified by a mutualistic interaction between Dobzhansky, Alfred Emerson and Ernst Mayr after the second world war. By the 1950s and early 1960s, these authors had developed an influential concept of species as coadapted genetic complexes at equilibrium. At this time many features of species were seen as group advantages maintained by selection to avoid breakdown of beneficial coadaptation and the ‘gene pool’. Speciation thus seemed difficult. It seemed to require, more so than today, an external deus ex machina , such as allopatry or the founder effect, rather than ordinary within-species processes of natural selection, sexual selection, drift and gene flow. In the mid-1960s, the distinctions between group and individual selection were clarified. Dobzhansky and Mayr both understood the implications, but their views on species changed little. These group selectionist ideas now seem peculiar, and are becoming distinctly less popular today. Few vestiges of group selectionism and species-level adaptationism remain in recent reviews of speciation. One wonders how many of our own cherished views on evolution will seem as odd to future biologists.


2013 ◽  
Vol 22 (21) ◽  
pp. 5382-5396 ◽  
Author(s):  
Francesco Cicconardi ◽  
Pietro P. Fanciulli ◽  
Brent C. Emerson

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