Molecular analysis of phylogeographic subspecies in three Ponto-Caspian sturgeon species

Abstract

Sturgeons (Order Acipenseriformes) represent an extremely valuable natural resource that is now facing depletion. In the current study we evaluate if the traditional classification in subspecies of Acipenser gueldenstaedtii, Acipenser stellatus and Huso huso, endemic to Ponto-Caspian region is sustained by molecular analysis and if these represent Evolutionary Significant Units (ESUs) that should be managed separately in conservation programs. To examine the classification of taxonomic entities we sequenced a fragment of the mitochondrial control region in case of three sturgeon species that inhabit the North-western of Black Sea and migrate for reproduction in the Lower Danube. Beside these sequences, we used previously published sequences from sturgeon individuals sampled in the Black Sea, Azov Sea and Caspian Sea. We determined the genetic diversity and genetic differentiation, conducted a Population Aggregation Analysis (PAA) and inferred an intraspecific molecular phylogeny and haplotype network. The results indicated a low level of genetic differentiation between the geographically designated subspecies and did not support a significant divergence or reciprocal monophyly between them. Our results confirm previous genetic studies with smaller samples sizes, but additional analyses including nuclear markers should be conducted for proper recommendations aiming at the development of conservation programs.

Defining criteria for the reintroduction of locally extinct populations based on contemporary and ancient genetic diversity: The case of the Adriatic Beluga sturgeon (Huso huso)

“…The Beluga sturgeon (Huso huso) is an iconic species with high economical and traditional relevance actually managed through trade control and hatchery supplementation programs (Doukakis et al, 2010). Historically, this anadromous species was common in both Ponto-Caspian and Adriatic regions (Doukakis et al, 2010;Dudu et al, 2014). As a consequence of its migratory behaviour, dam construction represents a key factor for the decline of this species, drastically altering its habitat by precluding access to the majority of historical spawning grounds, therefore reducing the reproductive success (Birstein et al, 1997).…”

Northern Bobwhite (Colinus virginianus) Mitochondrial Population Genomics Reveals Structure, Divergence, and Evidence for Heteroplasmy

“…Herein, we conducted a series of comparative analyses to determine whether similar population inferences or conclusions could be deduced from partial (i.e., partial or complete D-loop) and complete mitogenome nucleotide sequence data for 53 bobwhites (n = 6 ecoregions across TX and OK). As expected, haplotype diversity increases with the inclusion of increasing levels of mitogenomic sequence data, and nucleotide diversity decreases, the latter being due to the fact that nucleotide diversity is directly impacted by localized hyper-variability within short fragments of the mitochondria that are commonly targeted for population analyses (i.e., partial or complete D-Loop; See Table 1 ) (for review see [ 3 , 59 – 63 ]). Median joining haplotype networks [ 64 ] constructed for partial bobwhite mitogenome sequences demonstrated an overt lack of resolution for drawing phylogenetic or population inferences in the bobwhite, as compared to networks constructed using complete mitogenome sequence data (Figs 1 and 2 ).…”

“…A comparative summary of all bobwhite mitochondrial analyses of diversity are presented in Table 1 . Moreover, the true degree of mitogenome divergence and population structure among our sampled bobwhites was not detectable when popular mitogenome fragments (i.e., partial or complete D-Loop) (for review see [ 3 , 59 – 63 ]) were analyzed (Figs 1 and 2 ). Nevertheless, similar to a previous bobwhite mitochondrial study [ 3 ], we did not observe strong phylogeographical clustering among the six surveyed U.S. Environmental Protection Agency (EPA) level III ecoregions ( http://archive.epa.gov/wed/ecoregions/web/html/level_iii_iv-2.html ; Fig 2 ).…”

“…For bobwhite samples included in the present study, utilization of small, popular mitochondrial fragments [ 3 , 59 – 63 ] were observed to be largely insufficient to elucidate the true mitogenome haplotype structure and corresponding levels of divergence within a structured population. Likewise, discordant demographic inferences and failure to detect the extent of population substructure were also possible, as evidenced by small versus complete mitogenome sequence analyses.…”

Differential Morphological, Structural and Biological Characteristics of Cysts in Heterodera Species in Korea

“…Considering the previous studies mentioned above and the morphological and structural characteristics examined in our study and the molecular characteristics of cysts in a previous study (Kang et al, 2016), it is believable that all three nematodes belong to Heterodera morphologically and molecular-genetically, and the morphological criteria that have long been used previously in the classification of plant-parasitic or soil-borne nematodes may be as valid as current molecular genetic taxonomic criteria at least in higher taxa (≥ genus) (Kang et al, 2016;Mwamula et al, 2018;Subbotin et al, 2000). However, molecular genetic analyses of cysts may have more validated in species classification rather than morphological and structural characteristics because species characteristics are closely exerted in genetic levels (Dudu et al, 2001).…”