Information about Chronospecies
A chronospecies is a species which changes physically, morphologically, genetically, and/or behaviorally over time on an evolutionary scale such that the originating species and the species it becomes could not be classified as the same species had they existed at the same point in time. Throughout this change, there is only one species in the lineage living at any point in time, as opposed to cases where one species branches off into many through divergent evolution. As opposed to paleospecies (see below), "chronospecies" is the general term for the elements of a sequential succession of species evolving into another, anywhere in time, for any length of time, with or without having extant descendants.
If one has young fossil material - 100.000s to a few millions of years old or so - that is indistinguishable[1] from a living species, it could be considered to represent a chronospecies that is the immediate ancestor of the living taxon. Similarly, if one has a morphologically unchanged fossil record that stretches for tens of millions of years, longer than distinct species are usually known to exist judging from the fossil record, this would obviously represent the remains of several species. Taxa described based on such material are termed pal(a)eospecies. These are often not universally accepted as distinct, as they are not unequivocally identifiable without robust stratigraphic information. See e.g. Howard (1947) for a discussion of this problem.
With a phyletic gradualism model of evolution, it can be difficult to separate chronospecies, since morphological changes accumulate over time and two very different organisms could be connected by a series of intermediaries. In practice, chronospecies are usually recognized because two species in the same lineage are named by palaeontologists without knowledge of any intermediate organisms. When organisms evolve by punctuated equilibrium, chronospecies can be readily seen in the fossil record when a lineage changes without splitting.
Prehistoric (but comparatively recent - usually Late Pleistocene) subspecies of extant taxa which evolved in a similar way as chronospecies are called pal(a)eosubspecies Many of those are known from subfossil material and most have changed in size adapting to the climatic changes during the last ice age (see Bergmann's Rule).
Behavior or behaviour
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FOSSIL is a standard for allowing serial communication for telecommunications programs under the DOS operating system.
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Paleontology, palaeontology or palæontology (from Greek: paleo, "ancient"; ontos
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Speciation is the evolutionary process by which new biological species arise. There are four modes of natural speciation, based on the extent to which speciating populations are geographically isolated from one another:
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If one has young fossil material - 100.000s to a few millions of years old or so - that is indistinguishable[1] from a living species, it could be considered to represent a chronospecies that is the immediate ancestor of the living taxon. Similarly, if one has a morphologically unchanged fossil record that stretches for tens of millions of years, longer than distinct species are usually known to exist judging from the fossil record, this would obviously represent the remains of several species. Taxa described based on such material are termed pal(a)eospecies. These are often not universally accepted as distinct, as they are not unequivocally identifiable without robust stratigraphic information. See e.g. Howard (1947) for a discussion of this problem.
With a phyletic gradualism model of evolution, it can be difficult to separate chronospecies, since morphological changes accumulate over time and two very different organisms could be connected by a series of intermediaries. In practice, chronospecies are usually recognized because two species in the same lineage are named by palaeontologists without knowledge of any intermediate organisms. When organisms evolve by punctuated equilibrium, chronospecies can be readily seen in the fossil record when a lineage changes without splitting.
Prehistoric (but comparatively recent - usually Late Pleistocene) subspecies of extant taxa which evolved in a similar way as chronospecies are called pal(a)eosubspecies Many of those are known from subfossil material and most have changed in size adapting to the climatic changes during the last ice age (see Bergmann's Rule).
Examples
- Coragyps (chronospecies)
- Gymnogyps (palaeosubspecies)
- Panthera (numerous chrono- and paleospecies and -subspecies)
See also
- Valdiviathyris (no visible change since the Priabonian, 35 million years ago)
Footnotes
1. ^ Or only quantitatively distinguished, e.g. by minor differences in size but not in proportions.
References
- Howard, Hildegarde (1947): An ancestral Golden Eagle raises a question in taxonomy. Auk 64(2): 287-291. PDF fulltext
- Stanley, S. M. (1978) "Chronospecies' longevities, the origin of genera, and the punctuational model of evolution," Paleobiology, 4, 26-40.
- Evolutionary species vs. chronospecies from Dr. Steven M. Carr, Memorial University of Newfoundland biology department
Speciation guide | |
|---|---|
| Basic concepts: | Species • Chronospecies • Speciation • Cline |
| Modes of speciation: | Allopatric • Peripatric • Parapatric • Sympatric • Polyploidy • Paleopolyploidy |
| Auxiliary mechanisms: | Sexual selection • Assortative mating • Punctuated equilibrium |
| Intermediate stages: | Hybrid • Haldane's rule • Ring species |
species is one of the basic units of biological classification. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring.
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Comparative anatomy is the study of similarities and differences in the anatomy of organisms. It is closely related to evolutionary biology and phylogeny (the evolution of species).
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Genetics is the science of heredity and variation in living organisms.[1][2] Knowledge of the inheritance of characteristics has been implicitly used since prehistoric times for improving crop plants and animals through selective breeding.
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Behavior or behaviour
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Divergent evolution occurs when two or more biological characteristics have a common evolutionary origin but have diverged over evolutionary time. This is also known as adaptation or adaptive evolution.
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- For other uses of the term, see Fossil (disambiguation)
FOSSIL is a standard for allowing serial communication for telecommunications programs under the DOS operating system.
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For the journal, see .
A taxon (plural taxa), or taxonomic unit, is a name designating an organism or group of organisms. A taxon is assigned a rank and can be placed at a particular level in a systematic hierarchy reflecting evolutionary..... Click the link for more information.
Stratigraphy, a branch of geology, studies rock layers and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy includes two related subfields: lithologic or lithostratigraphy and biologic stratigraphy or
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Phyletic gradualism is a macroevolutionary hypothesis rooted in uniformitarianism. The hypothesis states that species continue to adapt to new challenges over the course of their history, gradually becoming new species.
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- Palaeontology redirects here. For the scientific journal, see Palaeontology (journal).
Paleontology, palaeontology or palæontology (from Greek: paleo, "ancient"; ontos
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Punctuated equilibrium (sometimes referred to as punctuated equilibria) is a theory in evolutionary biology, which posits that evolution amongst sexually reproducing species takes place in rapid bursts, separated by long periods in which little change occurs.
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The Late Pleistocene (also known as Upper Pleistocene or the Tarantian) is a stage of the Pleistocene Epoch. The beginning of the stage is defined by the base of Eemian interglacial phase before final glacial episode of Pleistocene 126,000 ± 5,000 years ago.
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Subfossil refers to remains whose fossilization process is not complete, either for lack of time or because the condition in which they were buried were not optimal for fossilization.
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An adaptation is a positive characteristic of an organism that has been favored by natural selection.[1] The concept is central to biology, particularly in evolutionary biology.
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The Wisconsin (in North America), Devensian (in the British Isles), Midlandian (in Ireland), Würm (in the Alps), and Weichsel (in northern central Europe) glaciations
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Bergmann's Rule is a principle that correlates environmental temperature with body mass in warm-blooded animals. It asserts that within a species, the body mass increases with latitude and colder climate.
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Coragyps
Saint-Hilaire, 1853
Species: C. atratus
Binomial name
Coragyps atratus
(Bechstein, 1793)
Subspecies
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Saint-Hilaire, 1853
Species: C. atratus
Binomial name
Coragyps atratus
(Bechstein, 1793)
Subspecies
- C. a.
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Gymnogyps
Lesson, 1842
Species: G. californianus
Binomial name
Gymnogyps californianus
(Shaw, 1797)
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Lesson, 1842
Species: G. californianus
Binomial name
Gymnogyps californianus
(Shaw, 1797)
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Panthera
Oken, 1816
Type species
Felis pardus
Linnaeus, 1758
Panthera is a genus of the family Felidae (the cats), which contains four well-known living species: the Lion, the Tiger, the Jaguar, and the Leopard.
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Oken, 1816
Type species
Felis pardus
Linnaeus, 1758
Panthera is a genus of the family Felidae (the cats), which contains four well-known living species: the Lion, the Tiger, the Jaguar, and the Leopard.
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The Priabonian (also known as Jacksonian or Runangan) is the final stage of the Eocene Epoch. It spans the time between 37.2 ± 0.1 Ma and 33.9 ± 0.1 Ma (million years ago).
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The Auk is a quarterly journal and the official publication of the American Ornithologists' Union, having been continuously published by that body since 1884. The journal contains articles relating scientific studies of the anatomy, behavior, and distribution of birds.
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species is one of the basic units of biological classification. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring.
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Speciation is the evolutionary process by which new biological species arise. There are four modes of natural speciation, based on the extent to which speciating populations are geographically isolated from one another:
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In population genetics, a cline is a gradual change of a character or feature (phenotype) in a species over a geographical area, often as a result of environmental heterogeneity.
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Allopatric speciation, also known as geographic speciation, is the phenomenon where huge biological populations are physically isolated by an extrinsic barrier and evolve intrinsic (genetic) reproductive isolation, such that if the barrier breaks down, individuals of the
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Peripatric speciation is a form of speciation, the formation of new species through evolution. In this form, new species are formed in isolated peripheral populations; this is similar to allopatric speciation in that populations are isolated and prevented from exchanging genes.
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Parapatric speciation is a form of speciation that occurs due to variations in mating frequency of a population within a continuous geographical area.
In this model, the parent species lives in a continuous habitat, in contrast with allopatric speciation where subpopulations
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In this model, the parent species lives in a continuous habitat, in contrast with allopatric speciation where subpopulations
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Sympatric Speciation is the genetic divergence of multiple populations (from a single parent species) inhabiting the same geographic region; such that those populations become different species.
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Polyploidy is the condition of some biological cells and organisms manifested by the presence of more than two homologous sets of chromosomes. Polyploid types are termed according to the number of chromosome sets in the nucleus: triploid (three sets; 3x),
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