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{{short description|A phylogenetic lineage that is inferred to exist but has no fossil record.}}
{{short description|A phylogenetic lineage that is inferred to exist but has no fossil record.}}
[[File:Ichthyosauria phylogeny.jpg|thumb|upright=1.3|Phylogeny of [[ichthyosaurs]]. Thick horizontal lines signify the existence of a fossil record for the respective time and taxa. Thin lines represent ghost lineages.]]
[[File:Ichthyosauria phylogeny.jpg|thumb|upright=1.3|Phylogeny of [[ichthyosaurs]]. Thick horizontal lines signify the existence of a fossil record for the respective time and taxa. Thin lines represent ghost lineages.]]
A '''ghost lineage''' is a [[phylogenetic]] [[Lineage (evolution)|lineage]] that is inferred to exist (inferred-existence) but has no [[fossil]] record.<ref name=norell1992/> The process of determining a ghost lineage relies on fossilized evidence before and after the hypothetical existence of the lineage and extrapolating relationships between organisms based on phylogenetic analysis.<ref name=":0">[http://earth.geology.yale.edu/~ajs/1993/11.1993.15Norell.pdf Norell, M. A. “Tree-Based Approaches to Understanding History; Comments on Ranks, Rules and the Quality of the Fossil Record.” ''American Journal of Science'', vol. 293, no. A, Jan. 1993, pp. 407–417., doi:10.2475/ajs.293.a.407.]</ref>
A '''ghost lineage''' is a hypothesized ancestor in a species lineage that has left no fossil evidence yet can be inferred to exist because of gaps in the fossil record or genomic sequences.<ref>{{Cite journal|last=Lorente-Galdos|first=Belen|last2=Lao|first2=Oscar|last3=Serra-Vidal|first3=Gerard|last4=Santpere|first4=Gabriel|last5=Kuderna|first5=Lukas F. K.|last6=Arauna|first6=Lara R.|last7=Fadhlaoui-Zid|first7=Karima|last8=Pimenoff|first8=Ville N.|last9=Soodyall|first9=Himla|last10=Zalloua|first10=Pierre|last11=Marques-Bonet|first11=Tomas|date=2019-04-26|title=Whole-genome sequence analysis of a Pan African set of samples reveals archaic gene flow from an extinct basal population of modern humans into sub-Saharan populations|url=https://doi.org/10.1186/s13059-019-1684-5|journal=Genome Biology|volume=20|issue=1|pages=77|doi=10.1186/s13059-019-1684-5|issn=1474-760X|pmc=PMC6485163|pmid=31023378}}</ref><ref>{{Cite web|url=https://ucmp.berkeley.edu/taxa/verts/archosaurs/ghost_lineages.php|title=Ghost lineages|last=Wedel|first=Matt|date=May 2010|website=|url-status=live|archive-url=|archive-date=|access-date=November 4, 2019}}</ref> The process of determining a ghost lineage relies on fossilized evidence before and after the hypothetical existence of the lineage and extrapolating relationships between organisms based on phylogenetic analysis.<ref name=":0">[http://earth.geology.yale.edu/~ajs/1993/11.1993.15Norell.pdf Norell, M. A. “Tree-Based Approaches to Understanding History; Comments on Ranks, Rules and the Quality of the Fossil Record.” ''American Journal of Science'', vol. 293, no. A, Jan. 1993, pp. 407–417., doi:10.2475/ajs.293.a.407.]</ref> Ghost lineages assume unseen diversity in the fossil record and serve as predictions for what the fossil record could eventually yield; these hypotheses can be tested by unearthing new fossils or running phylogenetic analyses.<ref>{{Cite book|title=The Mistaken Extinction: Dinosaur Evolution and the Origin of Birds|last=Dingus|first=L|last2=Rowe|first2=T|publisher=W. H. Freeman|year=1998|isbn=|location=New York|pages=}}</ref>


Ghost lineages are commonly confused with [[Lazarus taxa]], but there is a difference. For example, [[coelacanths]] (see below) are a Lazarus taxon, and the gaps in its fossil record are referred to as ghost lineages.<ref name=":2" />
Ghost lineages are commonly confused with [[Lazarus taxa]], but there is a difference. For example, [[coelacanths]] (see below) are a Lazarus taxon, and the gaps in its fossil record are referred to as ghost lineages.<ref name=":2" />

Revision as of 01:33, 4 December 2019

Phylogeny of ichthyosaurs. Thick horizontal lines signify the existence of a fossil record for the respective time and taxa. Thin lines represent ghost lineages.

A ghost lineage is a hypothesized ancestor in a species lineage that has left no fossil evidence yet can be inferred to exist because of gaps in the fossil record or genomic sequences.[1][2] The process of determining a ghost lineage relies on fossilized evidence before and after the hypothetical existence of the lineage and extrapolating relationships between organisms based on phylogenetic analysis.[3] Ghost lineages assume unseen diversity in the fossil record and serve as predictions for what the fossil record could eventually yield; these hypotheses can be tested by unearthing new fossils or running phylogenetic analyses.[4]

Ghost lineages are commonly confused with Lazarus taxa, but there is a difference. For example, coelacanths (see below) are a Lazarus taxon, and the gaps in its fossil record are referred to as ghost lineages.[5]

Name

In 1992, an article stated: "These additional entities are taxa [groups] that are predicted to occur by the internal branching structure of phylogenetic trees....I refer to these as ghost lineages because they are invisible to the fossil record."[6] Phylogenetic trees constructed based on fossil records and Darwin's theory of evolution often give an indication that species with similar phenotypes existed although its fossil has not been discovered.[7]

It is important to note that ghost lineages and ghost taxa are not the same; a ghost lineage is a single, direct connection between the descendant and the ancestor while a ghost taxon has multiple, split descendants.[3]

Examples

A selection of gaps within the fossil record of animals having hard body parts. Other notable examples are Chronoperates and Protanguilla.

When looking back at extinct organisms, there are some groups of organisms (or lineages) that have gaps in their fossil records. These organisms or species may be closely related to one another, but there are no traces in the fossil records or sediment beds that might shed some light on their origins. A classic example is the coelacanth, a type of fish related to the lungfishes and to primitive tetrapods. It seems that coelacanths have also been around for the past 80 million years but have failed to leave any fossils. The reason for this is their environment, which is deep water near volcanic islands; therefore, these sediments are hard to get to, giving these coelacanths an 80 million year gap or ghost lineage.[5] Another ghost lineage was that of the averostran theropods, a ghost lineage now reduced considerably due to the discovery of Tachiraptor.[8]

Duration and diversification

It is possible that the gaps in one organism's evolution can help us identify events in the fossil record. This can be done by calculating an actual ghost lineage's duration through intervals of time. It shows how the ghost lineage duration will go down as diversity goes up, helping to better understand when and maybe why the gaps happened.

See also

References

  1. ^ Lorente-Galdos, Belen; Lao, Oscar; Serra-Vidal, Gerard; Santpere, Gabriel; Kuderna, Lukas F. K.; Arauna, Lara R.; Fadhlaoui-Zid, Karima; Pimenoff, Ville N.; Soodyall, Himla; Zalloua, Pierre; Marques-Bonet, Tomas (2019-04-26). "Whole-genome sequence analysis of a Pan African set of samples reveals archaic gene flow from an extinct basal population of modern humans into sub-Saharan populations". Genome Biology. 20 (1): 77. doi:10.1186/s13059-019-1684-5. ISSN 1474-760X. PMC 6485163. PMID 31023378.{{cite journal}}: CS1 maint: PMC format (link) CS1 maint: unflagged free DOI (link)
  2. ^ Wedel, Matt (May 2010). "Ghost lineages". Retrieved November 4, 2019.{{cite web}}: CS1 maint: url-status (link)
  3. ^ a b Norell, M. A. “Tree-Based Approaches to Understanding History; Comments on Ranks, Rules and the Quality of the Fossil Record.” American Journal of Science, vol. 293, no. A, Jan. 1993, pp. 407–417., doi:10.2475/ajs.293.a.407.
  4. ^ Dingus, L; Rowe, T (1998). The Mistaken Extinction: Dinosaur Evolution and the Origin of Birds. New York: W. H. Freeman.
  5. ^ a b Wedel, Matt. "Ghost Lineages." Ghost Lineages, University of California Museum of Paleontology, May 2010, http://www.ucmp.berkeley.edu/taxa/verts/archosaurs/ghost_lineages.php
  6. ^ Norell, Mark A (1992). Taxic Origin and Temporal Diversity: The Effect of Phylogeny, in Extinction and Phylogeny. Columbia University Press, New York. pp. 89–118. {{cite book}}: Unknown parameter |editors= ignored (|editor= suggested) (help)
  7. ^ Norell, Mark A (1992). "The Fossil Record and Evolution: Comparing Cladistic and Paleontologic Evidence for Vertebrate History". Science. 255: 1690–1693. doi:10.1126/science.255.5052.1690.
  8. ^ Langer, Max C.; Rincón, Ascanio D.; Ramezani, Jahandar; Solórzano, Andrés; Rauhut, Oliver W.M. (2014). "New dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta formation, Venezuelan Andes". Royal Society Open Science. 1. Royal Society: 140–184. doi:10.1098/rsos.140184. PMC 4448901. PMID 26064540. Retrieved 17 October 2014.
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