David State Tarkhnishvili

Prof. David State Tarkhnishvili


Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 August 2024 in Zoological Journal of the Linnean Society
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WWWolfgang Wüster
Wolfgang Wüster
HKHinrich Kaiser
Hinrich Kaiser
MHMarinus S Hoogmoed
Marinus S Hoogmoed
LCLuis M P Ceríaco
Luis M P Ceríaco
LDLutz Dirksen
Lutz Dirksen
WBWolfgang Böhme
Wolfgang Böhme
A recent revision of the anacondas (Serpentes: Boidae: Eunectes), with the description of a new species of green anaconda, generated extensive publicity, but also provoked considerable controversy due to inadequacies of the evidence used and errors in nomenclature. We here use the case of this problematic publication to: (i) highlight common issues affecting species delimitations, especially an over-reliance on mitochondrial DNA data, and reiterate best practices; (ii) reanalyse the data available for anacondas to establish the true current state of knowledge and to highlight lines of further research; and (iii) analyse the nomenclatural history and status of the genus. While our analysis reveals significant morphological variation in both green and yellow anacondas, denser sampling and an analysis of informative nuclear markers are required for meaningful species delimitation in Eunectes. Tracing the history of name-bearing types establishes Trinidad as the type locality for Boa murina Linnaeus, 1758 and allows identification of the extant lectotype for the species. Finally, we emphasize the responsibility of both journals and authors to ensure that published taxonomic work meets the burden of evidence required to substantiate new species descriptions and that species are named in compliance with the rules of zoological nomenclature.

28 September 2015 in Biodiversity Data Journal
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YJYde de Jong
Yde de Jong
JKJuliana Kouwenberg
Juliana Kouwenberg
LBLouis Boumans
Louis Boumans
CHCharles Hussey
Charles Hussey
RHRoger Hyam
Roger Hyam
SUSandrine Ulenberg
Sandrine Ulenberg
Reliable taxonomy underpins communication in all of biology, not least nature conservation and sustainable use of ecosystem resources. The flexibility of taxonomic interpretations, however, presents a serious challenge for end-users of taxonomic concepts. Users need standardised and continuously harmonised taxonomic reference systems, as well as high-quality and complete taxonomic data sets, but these are generally lacking for non-specialists. The solution is in dynamic, expertly curated web-based taxonomic tools. The Pan-European Species-directories Infrastructure (PESI) worked to solve this key issue by providing a taxonomic e-infrastructure for Europe. It strengthened the relevant social (expertise) and information (standards, data and technical) capacities of five major community networks on taxonomic indexing in Europe, which is essential for proper biodiversity assessment and monitoring activities. The key objectives of PESI were: 1) standardisation in taxonomic reference systems, 2) enhancement of the quality and completeness of taxonomic data sets and 3) creation of integrated access to taxonomic information. This paper describes the results of PESI and its future prospects, including the involvement in major European biodiversity informatics initiatives and programs.

5 February 2018 in Ecology and Evolution
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LNLevan Ninua
Levan Ninua
DTDavid State Tarkhnishvili
David State Tarkhnishvili
EGElguja Gvazava
Elguja Gvazava
Current taxonomy of western Eurasian trout leaves a number of questions open; it is not clear to what extent some species are distinct genetically and morphologically. The purpose of this paper was to explore phylogeography and species boundaries in freshwater and anadromous trout from the drainages of the Black and the Caspian Seas (Ponto‐Caspian). We studied morphology and mitochondrial phylogeny, combining samples from the western Caucasus within the potential range of five nominal species of trout that are thought to inhabit this region, and using the sequences available from GenBank. Our results suggest that the genetic diversity of trout in the Ponto‐Caspian region is best explained with the fragmentation of catchments. (1) All trout species from Ponto‐Caspian belong to the same mitochondrial clade, separated from the other trout since the Pleistocene; (2) the southeastern Black Sea area is the most likely place of diversification of this clade, which is closely related to the clades from Anatolia; (3) The species from the Black Sea and the Caspian Sea drainages are monophyletic; (4) except for the basal lineage of the Ponto‐Caspian clade,Salmo rizeensis, all the lineages produce anadromous forms; (5) genetic diversification within the Ponto‐Caspian clade is related to Pleistocene glacial waves; (6) the described morphological differences between the species are not fully diagnostic, and some earlier described differences depend on body size; the differences between freshwater and marine forms exceed those between the different lineages. We suggest a conservative taxonomic approach, using the namesS. rizeensisandSalmo labraxfor trout from the Black Sea basin andSalmo caspiusandSalmo ciscaucasicusfor the fish from the Caspian basin.

17 June 2013 in Biological Journal of the Linnean Society
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DTDavid State Tarkhnishvili
David State Tarkhnishvili
MMMarine Murtskhvaladze
Marine Murtskhvaladze
AGAlexander Gavashelishvili
Alexander Gavashelishvili
Given sufficient time and limited gene flow, evolutionary lineages tend to transform into separate species. Mechanisms preventing assimilation during

8 June 2020 in PLOS ONE
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MMMarine Murtskhvaladze
Marine Murtskhvaladze
DTDavid State Tarkhnishvili
David State Tarkhnishvili
CACort L Anderson
Cort L Anderson
AKAdam Kotorashvili
Adam Kotorashvili
We generated a phylogeny for Caucasian rock lizards (Darevskia), and included six other families of true lizards (Lacertini), based on complete mitochondrial genome analysis. Next-generation sequencing (NGS) of genomic DNA was used to obtain 16 new mitogenomes of Darevskia. These, along with 35 sequences downloaded from GenBank: genera Darevskia, Zootoca, Podarcis, Phoenicolacerta, Takydromus, Lacerta, and Eremias—were used in the analysis. All four analytical methods (Bayesian Inference, BI; Maximum Likelihood, ML; Maximum Parsimony, MP; and Neighbor-Joining, NJ) showed almost congruent intra-generic topologies for Darevskia and other lizard genera. However, ML and NJ methods on one side, and BI and MP methods on the other harvested conflicting phylogenies. The ML/NJ topology supports earlier published separation of Darevskia into three mitochondrial clades (Murphy, Fu, Macculloch, Darevsky, and Kupinova, 2000), but BI and MP topologies support that the basal branching occurred between D. parvula from the western Lesser Caucasus and the rest of Darevskia. All topologies altered the phylogenetic position of some individual species, including D. daghestanica, D. derjugini, and D. chlorogaster. Reanalysis after excluding four saturated genes from the data set, and excluding genus Eremias gives fully convergent topologies. The most basal branching for true lizards was between Far Eastern Takydromus and the Western Eurasian genera (BI). Comparing phylogenetic performance of individual genes relative to whole mitogenome data, concatenated 16S RNA (the least saturated gene in our analyses) and Cytochrome b genes generate a robust phylogeny that is fully congruent with that based on the complete mitogenome.

21 February 2017 in Biological Journal of the Linnean Society
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DTDavid State Tarkhnishvili
David State Tarkhnishvili
MMMarine Murtskhvaladze
Marine Murtskhvaladze
CACort L. Anderson
Cort L. Anderson
The parthenogenetic lizards Darevskia armeniaca and Darevskia dahli are widespread throughout the Lesser Caucasus, although they occupy different habitats. While these forms differ in size, colour and scalation, both D. armeniaca and D. dahli have a hybrid origin and a common maternal progenitor species. Current evidence about the patrilineal origin is inconclusive, and the exact number of ancestral lineages remains unknown. This study aimed to investigate the distribution of mitochondrial haplotypes and alleles at five microsatellite loci in both the parthenogenetic forms and their presumed ancestors, in order to infer the number of ancestral hybridization events. Mitochondrial DNA analysis confirmed that both forms descend matrilineally from D. mixta from a limited geographic area in Central Georgia. Simultaneously, the majority of both D. armeniaca and D. dahli shared the same genotypes at two microsatellite loci, but differed at the other three. This observation and overall study of the distribution of the microsatellite genotypes suggests that (1) both D. armeniaca and D. dahli descend from very few, possibly single original hybridization event, most likely D. mixta and D. portschinskii, hence the hypothesis of different paternal species for these two forms is rejected; (2) expansion of the original parthenogenetic hybrid form into the range of D. valentini, followed by backcrosses of D. valentini males with the parthenogens, triggered development of a new parthenogenetic form, D. armeniaca; (3) backcrosses and mutation are more likely reasons of genetic diversity both between and within the parthenogenetic forms than their multiclonal origin.