Molecular phylogeny of one extinct and two critically endangered Central Asian sturgeon species (genus Pseudoscaphirhynchus) based on their mitochondrial genomes

Abstract

the enigmatic and poorly studied sturgeon genus Pseudoscaphirhynchus (Scaphirhynchinae: Acipenseridae) comprises three species: the Amu Darya shovelnose sturgeon (Pseudoscaphirhynchus kaufmanni (Bogdanow)), dwarf Amu Darya shovelnose sturgeon P. hermanni (Kessler), and Syr Darya shovelnose sturgeon (P. fedtschenkoi (Bogdanow). two species-P. hermanni and P. kaufmanni-are critically endangered due to the Aral Sea area ecological disaster, caused by massive water use for irrigation to support cotton agriculture, subsequent pesticide pollution and habitat degradation. for another species-P. fedtschenkoi-no sightings have been reported since 1960-s and it is believed to be extinct, both in nature and in captivity. in this study, complete mitochondrial (mt) genomes of these three species of Pseudoscaphirhynchus were characterized using illumina and Sanger sequencing platforms. Phylogenetic analyses showed the significant divergence between Amu Darya and Syr Darya freshwater sturgeons and supported the monophyletic origin of the Pseudoscaphirhynchus species. We confirmed that two sympatric Amu Darya species P. kaufmanni and P. hermanni form a single genetic cluster, which may require further morphological and genetic study to assess possible hybridization, intraspecific variation and taxonomic status and to develop conservation measures to protect these unique fishes. The animal diversity and classification remain complex with new species being continuously discovered and described. Meanwhile, an increase in human activity has led to the degradation of ecosystems, the destruction of native habitats and the direct extinction of many animal species 1. Museum specimens have become increasingly more valuable in evolutionary and conservation biology studies solving fundamental and applied problems using a novel arsenal of molecular genetic techniques. DNA isolation from historical samples and high-capacity DNA sequencing open up new opportunities associated with the investigation of evolution and phylogeny of extinct or endangered species 2-6. The order Acipenseriformes is an ancient fish group which is represented by two families: Polyodontidae and Acipenseridae 7. All of the extant species from the Acipenseridae family that inhabit North America and Eurasia are endangered and listed in CITES appendices 8,9 .

Fish diversity in a doubly landlocked country - a description of the fish fauna of Uzbekistan using DNA barcoding

“…In addition, among the four Leuciscus ( L. baicalensis, L. bergi, L. dzungaricus , and L. lindbergi ) species from Central Asia, Russia, and Mongolia, no interspecific differences were found based on the COI gene (J. Freyhof, personal communication). However, in Pseudoscaphirhynchus species, no interspecies differences were found either when using other rapidly evolving mtDNA markers [62], the entire mtDNA genome [63], or nDNA markers (our unpublished data). In fact, these two sturgeon species are morphologically easy to distinguish from each other [64].…”

“…A rare sturgeon fish, Acipenser nudiventris , is completely extinct in the Aral Sea basin [76]. Another sturgeon species endemic to the Syr Darya, Pseudoscaphirhynchus fedtschenkoi , has been possibly extinct since the 1990s [63]. The Syr Darya population of Capoetobrama kuschakewitschi has not been recorded in recent decades, and so far, this species has survived only in the lower reaches of the Amu Darya [77].…”

Ancient DNA of the Don-Hares Assumes the Existence of Two Distinct Mitochondrial Clades in Northeast Asia

“…Museum specimens are being used more and more often in evolutionary and conservation biology for solving fundamental and applied problems using a novel arsenal of molecular genetic techniques. DNA isolation from museum specimens and high-capacity DNA sequencing opens up new opportunities, associated with the investigation of the extinct or endangered species’ evolution and phylogeny [ 18 , 19 , 20 , 21 , 22 ]. In the previous study, comparative phylogenetic analysis of L. tanaiticus and L. timidus specimens, based on a 338-base pair (bp) fragment of the D-Loop of the mitochondrial genome, has not supported the assumption that L. tanaiticus and L. timidus belong to different species [ 23 ].…”

Associations Between Self- and Informant-Reported Abilities of Instrumental Activities of Daily Living and Cognitive Functions in Older Adults With Mild Cognitive Impairment

“…However, these deficits are still below those typically seen in patients with AD, although performance on neuropsychological tests may be predictive of the likelihood of developing AD (e.g., Belleville et al., 2017 ). Recent reviews suggest a frequent and early impairment of frontal-cortex-mediated executive functions (EFs), in addition to episodic memory impairments ( Chehrehnegar et al., 2019 ; Garcia-Alvarez et al., 2019 ; Guarino et al., 2019 ), and the extent of EF dysfunctions has been shown to be predictive of the conversion from MCI, specifically of the amnestic type, to AD ( Jung et al., 2020 ).…”