scholarly journals Effects of Oxytetracycline on Population Growth and Genetic Diversity of <italic>Euplotes vannus </italic>(Marine Protist)

2016 ◽  
Vol 46 (9) ◽  
pp. 1113-1120
Author(s):  
Jun GONG ◽  
QianQian ZHANG ◽  
Rao FU
Keyword(s):  
Genetic Diversity ◽  
Population Growth ◽  
Euplotes Vannus

scholarly journals Population history of the Northern corn leaf blight fungal pathogen Setosphaeria turcica in Europe

2020 ◽  
Author(s):  
Mireia Vidal-Villarejo ◽  
Fabian Freund ◽  
Hendrik Hanekamp ◽  
Andreas von Tiedemann ◽  
Karl Schmid
Keyword(s):  
Genetic Diversity ◽  
Population Growth ◽  
Central Europe ◽  
Fungal Pathogen ◽  
Rapid Expansion ◽  
Setosphaeria Turcica ◽  
Northern Corn Leaf Blight ◽  
Maize Cultivation ◽  
Genomic Regions ◽  
Corn Leaf Blight

AbstractSetosphaeria turcica is a major fungal pathogen of maize and causes the foliar disease Northern corn leaf blight (NCLB). It originates from tropical regions and expanded into Central Europe since the 1980s, simultaneously with a rapid increase of maize cultivation area in this region. To investigate evolutionary processes influencing the rapid expansion of S. turcica we sequenced 121 isolates from Central Europe, Western Europe and Kenya. Population genetic inference revealed five genetically distinct clusters that differ by their geographic distribution and emergence dates. One genetically diverse cluster is restricted to Kenya, and the four European clusters consist of three distinct clonal lineages with low genetic diversity and one genetically diverse cluster with several clonal sublineages. A comparison of two different coalescent models for genetic diversity in the most frequent and geographically widespread clonal lineage in Europe supported a model of neutral, strongly exponential population growth over models accounting for different types of selection. In contrast to Kenyan isolates, European isolates did not show sexual recombination despite the presence of both mating types MAT1-1 and MAT1-2 in Europe. Within clonal lineages phenotypic variation in virulence to different monogenic resistances likely originated from repeated de novo mutations in virulence genes of S. turcica. k-mer based association mapping between genetic clusters did not identify genomic regions associated with pathogen races but few genomic regions that are significantly differentiated between two clonal lineages and contain putative effector genes. Our results suggest that the rapid colonization of Europe by different clonal lineages of S. turcica was not driven by selection of virulent races but reflects a neutral demographic process of fast pathogen population growth fostered by a rapid expansion of the maize cultivation area in this region.

scholarly journals Increasing temperature weakens the positive effect of genetic diversity on population growth

2021 ◽  
Author(s):  
Alexandra L Singleton ◽  
Samantha Votzke ◽  
Andrea Yammine ◽  
Jean P Gibert
Keyword(s):  
Genetic Diversity ◽  
Population Growth ◽  
Global Climate ◽  
Extinction Risk ◽  
Genetic Stocks ◽  
Gxe Interactions ◽  
Plastic Changes ◽  
Warming World ◽  
Increasing Temperature ◽  
Positive Effect

Genetic diversity and temperature increases associated with global climate change, are known to independently influence population growth and extinction risk. Whether increasing temperature may influence the effect of genetic diversity on population growth, however, is not known. We address this issue in the model protist system Tetrahymena thermophila. We test the hypothesis that at temperatures closer to the species thermal optimum (i.e., the temperature at which population growth is maximal), genetic diversity should have a weaker effect on population growth compared to temperatures away from the thermal optimum. To do so, we grew populations of T. thermophila with varying levels of genetic diversity at increasingly warmer temperatures and quantified their intrinsic population growth rate, r. We found that genetic diversity increases population growth at cooler temperatures, but that as temperature increases, this effect almost completely disappears. We also show that a combination of changes in the amount of expressed genetic diversity (G), plastic changes in population growth across temperatures (E), and strong GxE interactions, underlie this temperature effect. Our results uncover important but largely overlooked temperature effects that have implications for the management of small populations with depauperate genetic stocks in an increasingly warming world.

scholarly journals Giraffe translocation population viability analysis

2020 ◽  
Vol 41 ◽  
pp. 245-252
Author(s):  
DE Lee ◽  
E Fienieg ◽  
C Van Oosterhout ◽  
Z Muller ◽  
M Strauss ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Growth ◽  
Genetic Load ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Sensitivity Analyses ◽  
Source Population ◽  
Viability Analysis ◽  
Probability Of Extinction ◽  
Founding Populations

Most populations of giraffes have declined in recent decades, leading to the recent IUCN decision to upgrade the species to Vulnerable status, and some subspecies to Endangered. Translocations have been used as a conservation tool to re-introduce giraffes to previously occupied areas or establish new populations, but guidelines for founding populations are lacking. To provide general guidelines for translocation projects regarding feasibility, we simulated various scenarios of translocated giraffe populations to identify viable age and sex distributions of founding populations using population viability analysis (PVA) implemented in Vortex software. We explored the parameter space for demography and the genetic load, examining how variation in founding numbers and sex ratios affected 100 yr probability of population extinction and genetic diversity. We found that even very small numbers of founders (N ≤ 10 females) can appear to be successful in the first decades due to transient positive population growth, but with moderate population growth rate and moderate genetic load, long-term population viability (probability of extinction <0.01) was only achieved with ≥30 females and ≥3 males released. To maintain >95% genetic diversity of the source population in an isolated population, 50 females and 5 males are recommended to compose the founding population. Sensitivity analyses revealed first-year survival and reproductive rate were the simulation parameters with the greatest proportional influence on probability of extinction and genetic diversity. These simulations highlight important considerations for translocation success and data gaps including true genetic load in wild giraffe populations.

scholarly journals Giraffe Translocation Population Viability Analysis

2019 ◽  
Author(s):  
Derek E. Lee ◽  
Elmar Fienieg ◽  
Cock Van Oosterhout ◽  
Zoe Muller ◽  
Megan Strauss ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Growth ◽  
Genetic Load ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Sensitivity Analyses ◽  
Source Population ◽  
Viability Analysis ◽  
Probability Of Extinction ◽  
Founding Populations

ABSTRACTMost populations of giraffes have declined in recent decades, leading to the recent decision to upgrade the species to vulnerable status, and some subspecies to endangered. Translocations have been used as a conservation tool to re-introduce giraffes to previously occupied areas or establish new populations, but guidelines for founding populations are lacking. To provide general guidelines for translocation projects regarding feasibility, we simulated various scenarios of translocated giraffe populations to identify viable age and sex distributions of founding populations using Population Viability Analysis (PVA) implemented in Vortex software. We explored the parameter space for demography (population growth rates: λ = 1.001, 1.010, 1.024), and the genetic load (number of lethal equivalents: LE = 2.5, 6.29, 12.6), examining how variation in founding numbers (N = 5 to 80 females) and sex ratios (M:F = 0.1 to 0.5) affected 100-year probability of extinction and genetic diversity. We found that even very small numbers of founders (N ≤10 females) can appear to be successful in the first decades due to transient positive population growth, but with moderate population growth rate and moderate genetic load, long-term population viability (probability of extinction <0.01) was only achieved with ≥30 females and ≥3 males released. To maintain >95% genetic diversity of the source population in an isolated population, 50 females and 5 males are recommended to comprise the founding population. Sensitivity analyses revealed first-year survival and reproductive rate were the simulation parameters with the greatest proportional influence on probability of extinction and genetic diversity. These simulations highlight important considerations for translocation success, and data gaps including true genetic load in wild giraffe populations.

scholarly journals Increasing temperature weakens the positive effect of genetic diversity on population growth

2021 ◽  
Author(s):  
Alexandra L. Singleton ◽  
Megan H. Liu ◽  
Samantha Votzke ◽  
Andrea Yammine ◽  
Jean P. Gibert
Keyword(s):  
Genetic Diversity ◽  
Population Growth ◽  
Increasing Temperature ◽  
Positive Effect
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