Insights into genetic variation and demographic history of sharpnose rays: Examinations of three species of Telatrygon (Elasmobranchii, Dasyatidae) from the Indo‐West Pacific

Abstract The Nashville crayfish (Faxonius shoupi) was federally listed as an endangered species in 1986 due to its limited distribution in the Mill Creek watershed; this waterway lies in the rapidly developing Nashville basin and has experienced habitat degradation due to agricultural run-off, contamination, and urban development. Recovery efforts, including dam removal and restoration of riparian zones, have improved conditions in Mill Creek and F. shoupi has increased in numbers and recolonized extirpated stream segments. However, a history of demographic bottlenecks and restricted gene flow may have negatively impacted the long-term recovery of this species. A recently discovered population of F. shoupi in a disjunct segment of the Lower Tennessee River at the Pickwick Tailwater may provide an additional source of genetic variation. Uncertainty surrounding the origins of the Pickwick population and its taxonomic relationship to F. shoupi in Mill Creek raises questions about the conservation and management implications of this population. We used mitochondrial sequencing and SNP genotyping to assess genetic variation and connectivity of F. shoupi in the Mill Creek drainage and to investigate the taxonomy and demographic history of the newly discovered population at Pickwick. We found substantial genetic variation and evidence of connectivity for samples throughout Mill Creek for both mitochondrial and genome-wide SNPs. Our results also suggest a recently severed connection between crayfish in Pickwick and Mill Creek. Unique mitochondrial haplotypes and SNP variation in the Pickwick population highlight the need for prioritizing this population in future conservation and management plans for this species.

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Trunk perimeter correlates with genetic bottleneck intensity and the level of genetic diversity in populations of Taxus baccata L

Annals of Forest Science ◽

10.1007/s13595-021-01080-1 ◽

2021 ◽

Vol 78 (3) ◽

Author(s):

Sara Stefanowska ◽

Katarzyna Meyza ◽

Grzegorz Iszkuło ◽

Igor J. Chybicki

Keyword(s):

Genetic Diversity ◽

Genetic Variation ◽

Demographic History ◽

Genetic Bottleneck ◽

Tree Age ◽

Taxus Baccata ◽

Census Size ◽

Germplasm Collections ◽

History Of ◽

The Mean

Abstract Key message Taxus baccata remnants established recently tend to contribute less to the species’ overall genetic variation than historical populations because they are subjected to a greater impact of the founder effect and genetic isolation. As tree trunk perimeter is a rough indicator of genetic variation in a population, this measure should be considered in conservation programs. Context Genetic variation within Taxus baccata (L.) populations is not associated with the current census size but correlates well with the effective size, suggesting that genetic drift intensity reflects variation in demographic histories. Aims We hypothesize that recently established populations are subjected to greater bottleneck than old remnants. Using the mean trunk perimeter as a surrogate of tree age, we test whether the demographic history and genetic variation are associated with the mean tree age. Methods Using 18 microsatellite markers, we analyze the genetic diversity and demographic history of 11 yew populations in Poland to assess the relationship between the mean trunk perimeter and the inferred genetic parameters. Results Populations reveal significant differences in levels of genetic variation and in the intensity and time of genetic bottleneck. After excluding an apparent outlier, the genetic variation is significantly greater while the bottleneck intensity lower in populations with a greater perimeter. Conclusion Due to continuous species decline and increasing fragmentation, the non-uniform contribution of yew remnants to the overall genetic variation tends to decrease together with the mean tree age. Germplasm collections for the species should take into account tree perimeter as a rough indicator of the genetic variation of a population.

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Assessing the origin, genetic structure and demographic history of the common pheasant (Phasianus colchicus) in the introduced European range

Scientific Reports ◽

10.1038/s41598-021-00567-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mohammad Reza Ashrafzadeh ◽

Rasoul Khosravi ◽

Carlos Fernandes ◽

Cecilia Aguayo ◽

Zoltán Bagi ◽

...

Keyword(s):

Genetic Variation ◽

Demographic History ◽

Population Expansion ◽

Game Species ◽

Recent Population Expansion ◽

Biogeographic Patterns ◽

Clustering Model ◽

History Of ◽

Common Pheasant ◽

The Common

AbstractThe common pheasant, a game species widely introduced throughout the world, can be considered as an ideal model to study the effects of introduction events on local adaptations, biogeographic patterns, and genetic divergence processes. We aimed to assess the origin, spatial patterns of genetic variation, and demographic history of the introduced populations in the contact zone of Central and Southeast Europe, using mitochondrial DNA control region sequences and microsatellite loci. Both types of molecular markers indicated relatively low to moderate levels of genetic variation. The mtDNA analyses revealed that common pheasants across the study area are divided into two distinct clades: B (mongolicus group) and F (colchicus group). Analyses of the microsatellite data consistently suggested a differentiation between Hungary and Serbia, with the pheasant population in Hungary being much more genetically homogeneous, while that of Serbia has much more genetic mixture and admixture. This cryptic differentiation was not detected using a non-spatial Bayesian clustering model. The analyses also provided strong evidence for a recent population expansion. This fundamental information is essential for adequate and effective conservation management of populations of a game species of great economic and ecological importance in the studied geographical region.

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Changes in Genetic Diversity and Demographic History of Jankowski’s Bunting (Emberiza Jankowskii), as Revealed by Mitochondrial DNA and Microsatellite Markers

10.21203/rs.3.rs-265651/v1 ◽

2021 ◽

Author(s):

Long Huang ◽

Guochen Feng ◽

Dan Li ◽

Weiping Shang ◽

Lishi Zhang ◽

...

Keyword(s):

Genetic Diversity ◽

Mitochondrial Dna ◽

Genetic Variation ◽

Microsatellite Markers ◽

Population Size ◽

Demographic History ◽

Effective Population ◽

High Genetic Diversity ◽

History Of ◽

Eastern Inner Mongolia

Abstract The genetic variation and distribution of a population depend largely on the demographic history. For instance, populations that have recently experienced shrinkage usually have a lower genetic diversity. However, some endangered species with a narrow distribution have a high genetic diversity resulting from large historical population sizes and long generation times. In addition, very recent population bottlenecks may not be reflected in the population’s genetic information. In this study, we used a mitochondrial DNA marker and 15 microsatellite markers to reveal the genetic diversity, recent changes, inbreeding, and demographic history of a Jankowski’s bunting (Emberiza jankowskii) population in eastern Inner Mongolia. The results show that the genetic diversity of the population remained at a relatively stable and high level until recently. Severe population shrinkage did not result in a considerable lack of genetic variation because of the large historical population size and relatively short periods of human disturbance. In addition, introgression and gene flow among populations compensate for the loss of genetic variation to some extent. Considering the current small effective population size and the existence of inbreeding, we recommend that habitat protection be continued to maximize the genetic diversity of the Jankowski’s bunting population.

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Population Genetics ofCaenorhabditis elegans: The Paradox of Low Polymorphism in a Widespread Species

Genetics ◽

10.1093/genetics/163.1.147 ◽

2003 ◽

Vol 163 (1) ◽

pp. 147-157 ◽

Cited By ~ 6

Author(s):

Arjun Sivasundar ◽

Jody Hey

Keyword(s):

Genetic Variation ◽

Microsatellite Loci ◽

Population Expansion ◽

Widespread Species ◽

C Elegans ◽

Model Research ◽

The World ◽

Natural Isolates ◽

History Of ◽

Low Levels

AbstractCaenorhabditis elegans has become one of the most widely used model research organisms, yet we have little information on evolutionary processes and recent evolutionary history of this widespread species. We examined patterns of variation at 20 microsatellite loci in a sample of 23 natural isolates of C. elegans from various parts of the world. One-half of the loci were monomorphic among all strains, and overall genetic variation at microsatellite loci was low, relative to most other species. Some population structure was detected, but there was no association between the genetic and geographic distances among different natural isolates. Thus, despite the nearly worldwide occurrence of C. elegans, little evidence was found for local adaptation in strains derived from different parts of the world. The low levels of genetic variation within and among populations suggest that recent colonization and population expansion might have occurred. However, the patterns of variation are not consistent with population expansion. A possible explanation for the observed patterns is the action of background selection to reduce polymorphism, coupled with ongoing gene flow among populations worldwide.

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