Chronospecies' longevities, the origin of genera, and the punctuational model of evolution

Paleobiology ◽  
1978 ◽  
Vol 4 (1) ◽  
pp. 26-40 ◽  
Author(s):  
Steven M. Stanley
Keyword(s):  
Mass Extinction ◽  
Distinct Species ◽  
Evolutionary Change ◽  
Late Cenozoic ◽  
Bottleneck Effect ◽  
Survivorship Curve ◽  
Higher Taxa ◽  
As Species ◽  
Living Species ◽  
Evolutionary Lineages

Taxonomists working with late Cenozoic faunas tend to view living species as starting points for the evaluation of chronospecies (i.e., segments of evolutionary lineages subjectively designated as species) that extend backward in time from the Recent. This practice makes it possible to construct a survivorship curve for late Cenozoic chronospecies by evaluating all fossil lineages believed to have survived to the present day. A survivorship curve is produced by plotting the fraction of these lineages existing at any time that have not undergone enough phyletic evolution that their extant representatives are assigned to new species. This kind of surviviorship curve has been plotted for chronospecies of mammals using the beginning of the Würm, rather than the Recent, as an endpoint in order to avoid the effects of the Würm and post-Würm mass extinction. The survivorship curve reveals that all but a small fraction of established chronospecies have long durations relative to intervals of time during which distinctive higher taxa have arisen. Phyletic turnover of species has been remarkably slow. Most net evolutionary change must have been associated with saltational speciation. Even the large majority of genera must have arisen rapidly by one or more divergent speciation events. Estimates of rates of extinction suggest that the bottleneck effect, in which constriction of a lineage is followed by re-expansion as a distinct species, cannot be a major source of evolutionary change. These conclusions, based on the evaluation of mammalian phylogeny, seem also to apply to other taxa of animals, supporting the punctuational model of evolution. The long durations of hominid species imply that the evolution of humans, like that of other mammals, conforms to this model.

Two new species in the Ficinia indica complex (Cyperaceae, tribe Cypereae) from South Africa

Phytotaxa ◽  
2017 ◽  
Vol 295 (1) ◽  
pp. 49
Author(s):  
ALUWANI A. TSHIILA ◽  
SAMSON B.M. CHIMPHANGO ◽  
JAN-ADRIAAN VILJOEN ◽  
A. MUTHAMA MUASYA
Keyword(s):  
New Species ◽  
Region Growing ◽  
Distinct Species ◽  
Cape Floristic Region ◽  
Morphological Data ◽  
Similar Species ◽  
Ecological Features ◽  
Dichotomous Key ◽  
As Species ◽  
Two New Species

Unclear boundaries between species hinder identification in the field and in herbaria, especially in species groups that can only be distinguished on the basis of subtle morphological and ecological features. One such taxon is Ficinia indica, widespread in the Greater Cape Floristic Region, growing on deep sandy soils between sea level and 1000 m elevation. Within its range, several phylogenetically related and morphologically similar species co-occur or occupy distinct habitats. Studies in herbaria show species in the Ficinia indica complex to be largely misidentified based on the use of qualitative information. Here, we investigate whether the six taxa recognized, based on one or a few characters, are supported as distinct species based on multivariate analysis of macro-morphological data. Two of the taxa were mostly separated whereas the other four taxa overlapped in multivariate space, but all the taxa could be distinguished using a single or a combination of morphological and ecological characters. We uphold the four previously recognized taxa (Ficinia argyropus, F. elatior, F. indica, F. laevis) as species, describe two new species (F. arnoldii and F. montana), and provide a dichotomous key for their identification.

scholarly journals Uneven distribution of cryptic diversity among higher taxa of parasitic worms

2010 ◽  
Vol 7 (2) ◽  
pp. 241-244 ◽  
Author(s):  
Robert Poulin
Keyword(s):  
Cryptic Species ◽  
Zoonotic Diseases ◽  
Helminth Parasites ◽  
Morphological Markers ◽  
Molecular Tools ◽  
Invasive Pathogens ◽  
Higher Taxa ◽  
As Species ◽  
Species Specific ◽  
Parasitic Worms

Cryptic species cause problems for estimates of biodiversity. In the case of parasites, cryptic species also plague efforts to detect potential zoonotic diseases or invasive pathogens. It is crucial to determine whether the likelihood of finding cryptic species differs among higher parasite taxa, to better calibrate estimates of diversity and monitor diseases. Using published reports of cryptic species of helminth parasites identified using molecular tools, I show that the number of species found is strongly related to the number of parasite individuals sequenced, weakly influenced by the number of host species from which parasites were obtained, and unaffected by the genetic markers used. After correction for these factors, more cryptic species of trematodes are found than in other helminth taxa. Although several features distinguish trematodes from other helminths, it is probable that our inability to discriminate among sibling species of trematodes results from their lack of structures serving as species-specific morphological markers. The available data suggest that current estimates of helminth diversity may need to be doubled (tripled for trematodes) to better reflect extant diversity.

Moving Targets

2012 ◽  
Author(s):  
Stephen J. Simpson ◽  
David Raubenheimer
Keyword(s):  
Life History ◽  
Natural Selection ◽  
Growth And Development ◽  
Early Growth ◽  
Evolutionary Change ◽  
Life History Strategies ◽  
Moving Targets ◽  
Gene Frequencies ◽  
Epigenetic Effects ◽  
As Species

This chapter studies intake and growth targets. For clarity, earlier chapters have treated intake and growth targets as static points integrated across a particular period in the life of an animal. In reality they are, of course, not static but rather trajectories that move in time. In the short term, the requirements of the animal change as environmental circumstances impose differing demands for nutrients and energy. At a somewhat longer timescale, targets move as the animal passes through the various stages of its life, from early growth and development to maturity, reproduction, and senescence. On an even longer timescale, nutritional traits are subject to natural selection and move as species evolve to exploit new or changing nutritional environments and to adopt differing life-history strategies. Presaging such evolutionary change in gene frequencies within populations are epigenetic effects, whereby the nutritional experiences of parents influence the behavior and metabolism of their offspring without requiring changes in gene frequencies.

Phase morphs and phoresy: New species of Antennoseius (Vitzthumia) mites (Acari: Mesostigmata: Ascidae) associated with pyrophilous carabids (Carabidae: Sericoda spp.) in Alberta, Canada

Zootaxa ◽  
2008 ◽  
Vol 1961 (1) ◽  
pp. 37-57 ◽  
Author(s):  
FRÉDÉRIC BEAULIEU ◽  
ANDREA D. DÉCHÊNE ◽  
DAVID E. WALTER
Keyword(s):  
New Species ◽  
North American ◽  
North American Species ◽  
Carabid Beetles ◽  
Free Living ◽  
Adult Females ◽  
As Species ◽  
Laboratory Cultures ◽  
Living Species ◽  
Mite Genus

The mite genus Antennoseius is composed of free-living species in soil and litter, as well as species that are phoretic on carabid beetles as adult females. Among approximately 60 described Antennoseius species, one North American species, A. janus, was found in laboratory cultures to have two female morphs: one granular, free-living morph, and one smooth, putatively phoretic morph. We here describe the adult females of A. perseus n. sp. and A. pyrophilus n. sp. collected from under the elytra of carabid beetles (Sericoda quadripunctata and S. bembidioides) associated with recently burned forests in Alberta, Canada. We also describe the female and male of a distinct, granular, non-phoretic morph of A. perseus, obtained from soil and by rearing the offspring of phoretic females. A key to the females of Antennoseius species having an ambulacrum on leg I (i.e. subgenus Vitzthumia) is provided.

Taxonomic survivorship curves and Van Valen's Law

Paleobiology ◽  
1975 ◽  
Vol 1 (1) ◽  
pp. 82-96 ◽  
Author(s):  
David M. Raup
Keyword(s):  
Fossil Record ◽  
Species Level ◽  
Extinction Rate ◽  
Survivorship Analysis ◽  
Survivorship Curve ◽  
Extinction Rates ◽  
Higher Taxa ◽  
Total Life ◽  
Adaptive Zone

As Van Valen has demonstrated, the taxonomic survivorship curve is a valuable means of investigating extinction rates in the fossil record. He suggested that within an adaptive zone, related taxa display stochastically constant and equal extinction rates. Such a condition is evidenced by straight survivorship curves for species and higher taxa. Van Valen's methods of survivorship analysis can be improved upon and several suggestions are presented. With proper manipulation of data, it is possible to pool the information from extinct and living taxa to produce a single survivorship curve and therefore a single estimate of extinction rate. If extinction rate is constant at the species level (producing a straight survivorship curve), higher taxa in the same group should be expected to have convex survivorship curves. The constancy of extinction rates (here termed Van Valen's Law) can and should be tested rigorously. Several methods are available, of which the Total Life method of Epstein is particularly effective.

scholarly journals EVOLUTIONARY CHANGE OF RESTRICTION CLEAVAGE SITES AND PHYLOGENETIC INFERENCE

Genetics ◽  
1986 ◽  
Vol 113 (1) ◽  
pp. 187-213
Author(s):  
Wen-Hsiung Li
Keyword(s):  
Nucleotide Substitution ◽  
Restriction Site ◽  
Evolutionary Change ◽  
Cleavage Sites ◽  
Restriction Sites ◽  
Unequal Rates ◽  
Mathematical Formulas ◽  
Recent Species ◽  
Restriction Cleavage ◽  
Evolutionary Lineages

ABSTRACT Mathematical formulas are developed for the evolutionary change of restriction cleavage sites in a DNA sequence, allowing unequal rates between transitional and transversional types of nucleotide substitution. Formulas are also developed for the probability of having a particular pattern of site changes among evolutionary lineages, such as parallel gains or losses of sites, and for inferring the presence or absence of a restriction site in an ancestral sequence from data on the present-day sequences. The unordered compatibility method is proposed for inferring the phylogenetic relationships among relatively closely related organisms, treating restriction sites as cladistic characters. Formulas are derived for the probability (P  +) of obtaining the correct network for a given number (N) of informative sites for the cases of four and five species. These formulas are applied to evaluate the performance of the method and to estimate the N value required for P  + to be 95% or larger. The method performs well when the branches between ancestral nodes and the branches leading to the two most recent species are more or less equal in length, but performs poorly when the latter two branches are considerably longer than the former.

scholarly journals Integrative taxonomy confirms the species status of the Himalayan langurs, Semnopithecus schistaceus Hodgson 1840

2019 ◽  
Author(s):  
Kunal Arekar ◽  
S. Sathyakumar ◽  
K. Praveen Karanth
Keyword(s):  
Taxonomic Status ◽  
Single Species ◽  
Distinct Species ◽  
Morphological Characters ◽  
Integrative Taxonomy ◽  
Multiple Sources ◽  
Species Status ◽  
Species Identity ◽  
Hanuman Langur ◽  
As Species

AbstractTaxonomy is replete with groups where the species identity and classification remain unresolved. One such group is the widely distributed Hanuman langur (Colobinae: Semnopithecus). For most part of the last century, Hanuman langur was considered to be a single species with multiple subspecies. Nevertheless, recent studies using an integrative taxonomy approach suggested that this taxon is a complex, with at least three species. However, these studies did not include the Himalayan population of the Hanuman langur whose taxonomic status remains unresolved. The Himalayan population of Hanuman langurs have been classified as a distinct species with multiple subspecies or have been subsumed into other species. These classification schemes are wholly based on morphological characters and which are sometimes insufficient to delimit different species. Here, we have integrated data from multiple sources viz. morphology, DNA, and ecology to resolve the taxonomy of the Himalayan langur and to understand its distribution limit. Our results with three lines of evidence corresponding to three different species concepts show that Himalayan langur is a distinct species from S. entellus of the plains. Additionally, these results did not show any support for splitting of the Himalayan langur into multiple subspecies. Our study supports the classification proposed by Hill (1939) and we recommend Semnopithecus schistaceus, Hodgson 1840 as species name for the Himalayan langur and subsume all the known subspecies into it.

scholarly journals Museum genomics reveals the Xerces blue butterfly ( Glaucopsyche xerces ) was a distinct species driven to extinction

2021 ◽  
Vol 17 (7) ◽  
pp. 20210123
Author(s):  
Felix Grewe ◽  
Marcus R. Kronforst ◽  
Naomi E. Pierce ◽  
Corrie S. Moreau
Keyword(s):  
Phylogenetic Analyses ◽  
Complete Mitochondrial Genome ◽  
Nuclear Genome ◽  
Haplotype Network ◽  
Distinct Species ◽  
Organellar Genome ◽  
A Genome ◽  
Living Species ◽  
Generation Sequencing ◽  
Blue Butterfly

The last Xerces blue butterfly was seen in the early 1940s, and its extinction is credited to human urban development. This butterfly has become a North American icon for insect conservation, but some have questioned whether it was truly a distinct species, or simply an isolated population of another living species. To address this question, we leveraged next-generation sequencing using a 93-year-old museum specimen. We applied a genome skimming strategy that aimed for the organellar genome and high-copy fractions of the nuclear genome by a shallow sequencing approach. From these data, we were able to recover over 200 million nucleotides, which assembled into several phylogenetically informative markers and the near-complete mitochondrial genome. From our phylogenetic analyses and haplotype network analysis we conclude that the Xerces blue butterfly was a distinct species driven to extinction.

Biography of the Earth

2021 ◽  
pp. 214-228
Author(s):  
Elisabeth Ervin-Blankenheim
Keyword(s):  
Mass Extinction ◽  
Ice Sheets ◽  
Late Cenozoic ◽  
Ice Ages ◽  
Quaternary Period ◽  
Asteroid Impact ◽  
The Earth ◽  
Ecological Resources ◽  
Extinction Event ◽  
Cenozoic Era

The last era in the Phanerozoic Eon, the Cenozoic Era, is detailed in this chapter. The rise and radiation of the mammals occurred during Cenozoic after the devastation wrought by the Chicxulub Asteroid impact at the end of the Mesozoic Era. Ecological resources and niches vacated by the dinosaurs because of the mass extinction were filled by the mammals with concurrent developments in plants. Changes in climate and the mid-Miocene warming happened mid-era, then drying out and opening of grasslands followed by a plunge into ice ages and the Pleistocene extinction event. The late Cenozoic witnessed the development of humankind as the great ice sheets from the Pleistocene started to melt and the climate warm. The planet started to look similar to how it appears to humans today, and the current age of the Earth is the Cenozoic Era, Quaternary Period, Holocene Epoch, Meghalayan Age.

The International Code of Zoological Nomenclature must be drastically improved before it is too late

Bionomina ◽  
2011 ◽  
Vol 2 (1) ◽  
pp. 1-104 ◽  
Author(s):  
Alain DUBOIS
Keyword(s):  
Biological Sciences ◽  
Integrative Taxonomy ◽  
Zoological Nomenclature ◽  
Biodiversity Crisis ◽  
Higher Taxa ◽  
Standards And Guidelines ◽  
Living Species ◽  
Code Compliance ◽  
Material Evidence ◽  
Current Code

At the beginning of the century of extinctions, science has only inventoried a very small proportion of the living species of the globe. In order to face the taxonomic urgency that results from this taxonomic gap combined with the biodiversity crisis, zootaxonomy needs efficient, rigorous and automatic nomenclatural Rules, that allow to spend a minimal time on nomenclatural problems—rather than investing time, energy and money in renaming millions of already named taxa in order to follow alternative nomenclatural systems, e.g., “phylogenetic” ones, that furthermore do not show theoretical superiority to the current Linnaean-Stricklandian one. The current Code, result of a 250-year improvement process, is based on very sound and healthy Rules, being theory-free regarding taxonomy, relying on objective allocation of nomina to taxa by a system of ostension using onomatophores, and on an objective basic Principle, priority, for recognizing the valid nomen of a taxon in case of synonymy or homonymy. Nevertheless, this nomenclatural system is certainly not perfect. It should be modified at least in nine directions: (1) it should adopt a technical terminology avoiding possible misinterpretations from outsiders of the field and even from specialists, and allowing a precise formalisation of its mode of functioning; (2) its plan should be drastically modified; (3) its Principles should be redefined, and some added; (4) material evidence for the allocation of nomina to taxa through specimens deposited in permanent collections should be given more weight; (5) it should incorporate all nomina of higher taxa, providing clear and strict universal Rules for their naming, whereas conserving the traditional nomina largely used in non-specialized systematic literature; (6) it should allow for the recognition of many more ranks at lower nomenclatural levels, i.e., just above genus, between genus and species, and below species; (7) it should provide much more stringent Rules for the protection against priority of “wellknown” nomina or sozonyms; (8) various “details” should be addressed, various Rules and Recommendations changed before a new edition of the Code is published; (9) the procedure of implementations of changes in the Code should be modified in order to involve zootaxonomists of the whole world in the decisions. In several instances, the Rules of the Code should become much more compulsory for all zoologists, editors and publishers, to avoid the publication of endless and sometimes most detrimental discussions among taxonomists which give a poor image of nomenclature and taxonomy among the biological sciences, such as bitter discussions about the “best” nomen to be used under a so-called “usage” philosophy, or about nomina to be applied to higher taxa. Code-compliance in zootaxonomic publications should be highlighted, and editors and publishers should require from authors who follow alternative nomenclatural Rules (or no rule at all) to make it clear by using particular modes of writing their nomina. It is argued here that if the Code of the 21st century does not evolve to incorporate these changes, it will prove unable to play its role in front of several important recent theoretical and practical developments of taxonomy and run the risk of being abandoned by a part of the international community of zootaxonomists. The latter could then adopt alternative “phylogenetic” nomenclatural Rules, despite the severe practical problems and theoretical flaws posed by such projects. This would be most detrimental for all comparative biological disciplines including systematics, and even for the unity of biology. In the course of this discussion, a few recommendations are given concerning the standards and guidelines suggested by recent authors for a good, modern, integrative taxonomy.

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