scholarly journals Genetic Diversity of Stellate Sturgeon in the Lower Danube River: The Impact of Habitat Contraction upon a Critically Endangered Population

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1115
Author(s):  
Daniela Nicoleta Holostenco ◽  
Mitică Ciorpac ◽  
Elena Taflan ◽  
Katarina Tošić ◽  
Marian Paraschiv ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Developmental Stages ◽  
Danube River ◽  
Critically Endangered ◽  
Genetic Structuring ◽  
The Danube River ◽  
Stellate Sturgeon ◽  
Loop Region ◽  
Increased Risk ◽  
The Impact

One of the last wild populations of the critically endangered stellate sturgeon (Acipenser stellatus) survives in the Danube River. Limited knowledge about the genetic structure, ecology, and evolution of this species led to poor and inconsistent management decisions with an increased risk for species extinction in the wild. Here we show the results of genetic structure screening of the Danube River wild population over 12 years timespan. Our research does not bring evidence of population recovery. No genetic structuring was identified at the mitochondrial level concerning spawning migration timing, sampling locations, and developmental stages. Eleven maternal lineages were revealed based on restriction fragment lengths analysis of the D-loop region, with one haplotype as the most frequent. While this could be the result of a massive restocking activity using a reduced number of spawners, our data does not support it. The selection of mitochondrial haplotypes under the pressure of habitat contraction and the narrower range of temperature variation since dams’ construction on the river could explain the observed distribution. Several factors of managerial concern are discussed. Our results provide baseline data on the mtDNA diversity in a critically endangered species of exceptionally high socioeconomic and conservation interest.

Indigenous forests of European black poplar along the Danube River: genetic structure and reliable detection of introgression

2015 ◽  
Vol 11 (5) ◽  
Author(s):  
Mihailo Jelić ◽  
Aleksandra Patenković ◽  
Marijana Skorić ◽  
Danijela Mišić ◽  
Zorana Kurbalija Novičić ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Danube River ◽  
The Danube River ◽  
Black Poplar ◽  
Reliable Detection

scholarly journals Genetic variation and cryptic lineage diversity of the Nigerian red-headed rock agama Agama agama associate with eco-geographic zones

2019 ◽  
Vol 65 (6) ◽  
pp. 713-724 ◽  
Author(s):  
Lotanna M Nneji ◽  
Adeniyi C Adeola ◽  
Fang Yan ◽  
Agboola O Okeyoyin ◽  
Ojo C Oladipo ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Geographic Distance ◽  
Climatic Conditions ◽  
Population Divergence ◽  
Geographic Isolation ◽  
Genetic Structuring ◽  
Derived Savanna ◽  
Wide Range ◽  
Conservation Actions ◽  
The Impact

AbstractNigeria is an Afrotropical region with considerable ecological heterogeneity and levels of biotic endemism. Among its vertebrate fauna, reptiles have broad distributions, thus, they constitute a compelling system for assessing the impact of ecological variation and geographic isolation on species diversification. The red-headed rock agama, Agama agama, lives in a wide range of habitats and, thus, it may show genetic structuring and diversification. Herein, we tested the hypothesis that ecology affects its genetic structure and population divergence. Bayesian inference phylogenetic analysis of a mitochondrial DNA (mtDNA) gene recovered four well-supported matrilines with strong evidence of genetic structuring consistent with eco-geographic regions. Genetic differences among populations based on the mtDNA also correlated with geographic distance. The ecological niche model for the matrilines had a good fit and robust performance. Population divergence along the environmental axes was associated with climatic conditions, and temperature ranked highest among all environmental variables for forest specialists, while precipitation ranked highest for the forest/derived savanna, and savanna specialists. Our results cannot reject the hypothesis that niche conservatism promotes geographic isolation of the western populations of Nigerian A. agama. Thus, ecological gradients and geographic isolation impact the genetic structure and population divergence of the lizards. This species might be facing threats due to recent habitat fragmentation, especially in western Nigeria. Conservation actions appear necessary.

scholarly journals Clinging to survival: Critically Endangered Chapman's pygmy chameleon Rhampholeon chapmanorum persists in shrinking forest patches

Oryx ◽  
2021 ◽  
pp. 1-6
Author(s):  
Krystal A. Tolley ◽  
Colin R. Tilbury ◽  
Jessica M. da Silva ◽  
Gary Brown ◽  
Yankho Chapeta ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Structure ◽  
Satellite Imagery ◽  
Critically Endangered ◽  
Forest Loss ◽  
Mitochondrial Marker ◽  
Forest Patches ◽  
Genetic Diversity And Structure ◽  
The Impact

Abstract The Critically Endangered Chapman's pygmy chameleon Rhampholeon chapmanorum is endemic to the low elevation rainforest of the Malawi Hills in southern Malawi. Much of this forest has been converted to agriculture and it was uncertain whether chameleon populations have persisted. We used current and historical satellite imagery to identify remaining forest patches and assess deforestation. We then surveyed forest patches for the presence of this chameleon, and assessed its genetic diversity and structure. We estimated that 80% of the forest has been destroyed since 1984, although we found extant populations of the chameleon in each of the patches surveyed. Differentiation of genetic structure was strong between populations, suggesting that gene flow has been impaired. Genetic diversity was not low, but this could be the result of a temporal lag as well as lack of sensitivity in the mitochondrial marker used. Overall, the impact of forest loss is assumed to have led to a large demographic decline, with forest fragmentation preventing gene flow.

scholarly journals High levels of genetic diversity and an absence of genetic structure among breeding populations of the endangered Rufous-backed Bunting in Inner Mongolia, China: implications for conservation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shi Li ◽  
Dan Li ◽  
Lishi Zhang ◽  
Weiping Shang ◽  
Bo Qin ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Mitochondrial Dna ◽  
Genetic Structure ◽  
Endangered Species ◽  
Habitat Loss ◽  
Inner Mongolia ◽  
Avian Species ◽  
Genetic Structuring ◽  
Breeding Populations ◽  
The Impact

Abstract Background The Rufous-backed Bunting, Emberiza jankowskii, is an endangered species that is primarily distributed in Inner Mongolia, China. The main threats to the continued persistence of this species are habitat loss and degradation. However, the impact of population loss on genetic diversity remains unclear. To support future conservation and management efforts, we assessed the genetic diversity and population structure of E. jankowskii using mitochondrial DNA and microsatellites. Methods Blood samples were collected from 7‒8-day-old nestlings in Inner Mongolia, China between May and August of 2012 and 2013. Mitochondrial DNA sequences and microsatellite markers were used to assess the genetic diversity, genetic structure and inbreeding of E. jankowskii. The results of genetic diversity and inbreeding were compared to other avian species. Results We found an unexpectedly high level of genetic diversity in terms of mitochondrial DNA and microsatellite compared to other avian species. However, there were high levels of gene flow and minimal genetic structuring, among the fragmented breeding populations of E. jankowskii in Inner Mongolia. These findings suggest that E. jankowskii in Inner Mongolia is a metapopulation. Despite the high genetic diversity of E. jankowskii, local populations in each small patch remain at risk of extinction due to habitat loss. In addition, the E. jankowskii population has a high risk of inbreeding. Conclusions To minimize further loss of genetic diversity of this endangered species, we suggest that the E. jankowskii in Inner Mongolia should be considered as a protected species for management purposes. Conservation efforts should concentrate on E. jankowskii habitat management. This may be most effectively achieved by protecting the current breeding habitats and prohibiting over-grazing.

scholarly journals The impact of sexual abuse on female development: Lessons from a multigenerational, longitudinal research study

2011 ◽  
Vol 23 (2) ◽  
pp. 453-476 ◽  
Author(s):  
Penelope K. Trickett ◽  
Jennie G. Noll ◽  
Frank W. Putnam
Keyword(s):  
Sexual Abuse ◽  
Stress Responses ◽  
Developmental Stages ◽  
Longitudinal Research ◽  
Observational Research ◽  
Female Development ◽  
Sexual Revictimization ◽  
Increased Risk ◽  
Health Initiatives ◽  
The Impact

AbstractThis is a report on the research design and findings of a 23-year longitudinal study of the impact of intrafamilial sexual abuse on female development. The conceptual framework integrated concepts of psychological adjustment with theory regarding how psychobiological factors might impact development. Participants included 6- to 16-year-old females with substantiated sexual abuse and a demographically similar comparison group. A cross-sequential design was used and six assessments have taken place, with participants at median age 11 at the first assessment and median age 25 at the sixth assessment. Mothers of participants took part in the early assessments and offspring took part at the sixth assessment. Results of many analyses, both within circumscribed developmental stages and across development, indicated that sexually abused females (on average) showed deleterious sequelae across a host of biopsychosocial domains including: earlier onsets of puberty, cognitive deficits, depression, dissociative symptoms, maladaptive sexual development, hypothalamic–pituitary–adrenal attenuation, asymmetrical stress responses, high rates of obesity, more major illnesses and healthcare utilization, dropping out of high school, persistent posttraumatic stress disorder, self-mutilation,Diagnostic and Statistical Manual of Mental Disordersdiagnoses, physical and sexual revictimization, premature deliveries, teen motherhood, drug and alcohol abuse, and domestic violence. Offspring born to abused mothers were at increased risk for child maltreatment and overall maldevelopment. There was also a pattern of considerable within group variability. Based on this complex network of findings, implications for optimal treatments are elucidated. Translational aspects of extending observational research into clinical practice are discussed in terms that will likely have a sustained impact on several major public health initiatives.

scholarly journals The impact of large dams on fluvial sedimentation: The Iron Gates Reservoir on the Danube River

2021 ◽  
Vol 61 (1) ◽  
Author(s):  
Constantin Nistor ◽  
Ionuț Săvulescu ◽  
Bogdan-Andrei Mihai ◽  
Liliana Zaharia ◽  
Marina Vîrghileanu ◽  
...  
Keyword(s):  
Alluvial Fan ◽  
Danube River ◽  
Sediment Distribution ◽  
Ship Traffic ◽  
The Danube River ◽  
Spatial Changes ◽  
Before And After ◽  
Diachronic Analysis ◽  
Fluvial Sedimentation ◽  
The Impact

Dam construction is one of the major human pressures impacting fluvial processes, including topography and hydro-sedimentary flows, as a result of the change in flow regime from fluvial to fluvial-lacustrine. This article investigates geomorphic changes at Iron Gates I, the largest reservoir on the Danube River, completed in 1972 for hydropower and navigation. The study focuses on a gulf area that emerged at the mouth of the Cerna River into the reservoir, highlighting spatial changes in topography and sediment distribution, based on a diachronic analysis of two datasets before and after the dam was built: one extracted from historical topographic maps and the other obtained from a bathymetric echo sounding survey, integrated within a GIS analysis. The results reveal the dominance of the sedimentation process, with an alluvium layer thickness up to 14 m. The current sediment pattern has changed the submerged morphology, leading to the formation of an alluvial fan at the mouth of the Cerna River and of a sedimentary bar between the Cerna Gulf and the Danube River’s channel. The siltation process together with the current underwater morphology limits ship traffic and the storage capacity of the reservoir.

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