A chronospecies is a species derived from a sequential development pattern that involves continual and uniform changes from an extinct ancestral form on an evolutionary scale. The sequence of alterations eventually produces a population that is physically, morphologically, and/or genetically distinct from the original ancestors. Throughout the change, there is only one species in the lineage at any point in time, as opposed to cases where divergent evolution produces contemporary species with a common ancestor. The related term paleospecies (or palaeospecies) indicates an extinct species only identified with fossil material. That identification relies on distinct similarities between the earlier fossil specimens and some proposed descendant although the exact relationship to the later species is not always defined. In particular, the range of variation within all the early fossil specimens does not exceed the observed range that exists in the later species.
In palaeontology, the evidence for species and evolution comes mainly from the comparative anatomy of fossils. A chronospecies is defined in a single lineage (solid line) whose morphology changes with time. At some point, palaeontologists judge that enough change has occurred that two forms (A and B), separated in time and anatomy, once existed. If only sporadic examples of each survive in the fossil record, the forms will appear sharply distinct.
A paleosubspecies (or palaeosubspecies) identifies an extinct subspecies that evolved into the currently-existing form. The connection with relatively-recent variations, usually from the Late Pleistocene, often relies on the additional information available in subfossil material. Most of the current species have changed in size and so adapted to the climatic changes during the last ice age (seeBergmann's Rule).
The further identification of fossil specimens as part of a "chronospecies" relies on additional similarities that more strongly indicate a specific relationship with a known species. For example,[1] relatively recent specimens, hundreds of thousands to a few million years old with consistent variations (such as always smaller but with the same proportions) as a living species might represent the final step in a chronospecies. The possible identification of the immediate ancestor of the living taxon may also rely on stratigraphic information to establish the age of the specimens.
The concept of chronospecies is related to the phyletic gradualism model of evolution, and it also relies on an extensive fossil record since morphological changes accumulate over time, and two very different organisms could be connected by a series of intermediaries.
^Howard, Hildegarde (1947). "An ancestral Golden Eagle raises a question in taxonomy" (PDF). The Auk. 64 (2): 287–291. doi:10.2307/4080550. JSTOR 4080550.
Further reading
Evolutionary species vs. chronospecies from Dr. Steven M. Carr, Memorial University of Newfoundland biology department
Stanley, S. M. (1978) "Chronospecies' longevities, the origin of genera, and the punctuational model of evolution," Paleobiology,4, 26–40.
External links
Look up chronospecies in Wiktionary, the free dictionary.
May 04, 2023
chronospecies, chronospecies, species, derived, from, sequential, development, pattern, that, involves, continual, uniform, changes, from, extinct, ancestral, form, evolutionary, scale, sequence, alterations, eventually, produces, population, that, physically,. A chronospecies is a species derived from a sequential development pattern that involves continual and uniform changes from an extinct ancestral form on an evolutionary scale The sequence of alterations eventually produces a population that is physically morphologically and or genetically distinct from the original ancestors Throughout the change there is only one species in the lineage at any point in time as opposed to cases where divergent evolution produces contemporary species with a common ancestor The related term paleospecies or palaeospecies indicates an extinct species only identified with fossil material That identification relies on distinct similarities between the earlier fossil specimens and some proposed descendant although the exact relationship to the later species is not always defined In particular the range of variation within all the early fossil specimens does not exceed the observed range that exists in the later species In palaeontology the evidence for species and evolution comes mainly from the comparative anatomy of fossils A chronospecies is defined in a single lineage solid line whose morphology changes with time At some point palaeontologists judge that enough change has occurred that two forms A and B separated in time and anatomy once existed If only sporadic examples of each survive in the fossil record the forms will appear sharply distinct A paleosubspecies or palaeosubspecies identifies an extinct subspecies that evolved into the currently existing form The connection with relatively recent variations usually from the Late Pleistocene often relies on the additional information available in subfossil material Most of the current species have changed in size and so adapted to the climatic changes during the last ice age see Bergmann s Rule The further identification of fossil specimens as part of a chronospecies relies on additional similarities that more strongly indicate a specific relationship with a known species For example 1 relatively recent specimens hundreds of thousands to a few million years old with consistent variations such as always smaller but with the same proportions as a living species might represent the final step in a chronospecies The possible identification of the immediate ancestor of the living taxon may also rely on stratigraphic information to establish the age of the specimens The concept of chronospecies is related to the phyletic gradualism model of evolution and it also relies on an extensive fossil record since morphological changes accumulate over time and two very different organisms could be connected by a series of intermediaries Contents 1 Examples 2 See also 3 References 4 Further reading 5 External linksExamples EditBison several paleospecies and subspecies Marine sloths paleospecies Coragyps chronospecies Gymnogyps paleospecies Panthera numerous chrono and paleospecies and subspecies Valdiviathyris no visible change since the Priabonian 35 million years ago See also EditOrthogenesisReferences Edit Howard Hildegarde 1947 An ancestral Golden Eagle raises a question in taxonomy PDF The Auk 64 2 287 291 doi 10 2307 4080550 JSTOR 4080550 Further reading EditEvolutionary species vs chronospecies from Dr Steven M Carr Memorial University of Newfoundland biology department Stanley S M 1978 Chronospecies longevities the origin of genera and the punctuational model of evolution Paleobiology 4 26 40 External links Edit Look up chronospecies in Wiktionary the free dictionary Retrieved from https en wikipedia org w index php title Chronospecies amp oldid 1112035785, wikipedia, wiki, book, books, library,
