scholarly journals Natural selection drives population divergence for local adaptation in a wheat pathogen

2019 ◽  
Author(s):  
Danilo Pereira ◽  
Daniel Croll ◽  
Patrick C. Brunner ◽  
Bruce A. McDonald
Keyword(s):  
Growth Rates ◽  
Common Garden ◽  
High Temperature Stress ◽  
Population Divergence ◽  
Stabilizing Selection ◽  
Evolutionary Potential ◽  
Local Conditions ◽  
Evolutionary Forces ◽  
Different Temperatures ◽  
Parastagonospora Nodorum

AbstractEvolution favors the emergence of locally-adapted optimum phenotypes that are likely to differ across a wide array of environmental conditions. The emergence of favorable adaptive characteristics is accelerated in agricultural pathogens due to the unique properties of agro-ecosystems. We performed a QST - FST comparison using 164 strains of Parastagonospora nodorum sampled from eight global field populations to disentangle the predominant evolutionary forces driving population divergence in a wheat pathogen. We used digital image analysis to obtain quantitative measurements of growth rate and melanization at different temperatures and under different fungicide concentrations in a common garden experiment. FST measures were based on complete genome sequences obtained for all 164 isolates. Our analyses indicated that all measured traits were under selection. Growth rates at 18°C and 24°C were under stabilizing selection (QST < FST), while diversifying selection (QST > FST) was the predominant evolutionary force affecting growth under fungicide and high temperature stress. Stabilizing selection (QST < FST) was the predominant force affecting melanization across the different environments. Melanin production increased at 30°C but was negatively correlated with higher growth rates, consistent with a trade-off under heat stress. Our results demonstrate that global populations of P. nodorum possess significant evolutionary potential to adapt to changing local conditions, including warmer temperatures and applications of fungicides.

scholarly journals Intraspecific genomic variation and local adaptation in a young hybrid species

2019 ◽  
Author(s):  
Angélica Cuevas ◽  
Mark Ravinet ◽  
Glenn-Peter Sætre ◽  
Fabrice Eroukhmanoff
Keyword(s):  
Genetic Variation ◽  
Local Adaptation ◽  
Climatic Variation ◽  
Genomic Variation ◽  
Population Divergence ◽  
Parent Species ◽  
Evolutionary Potential ◽  
Variable Environment ◽  
Hybrid Species ◽  
Species Population

ABSTRACTHybridization increases genetic variation, hence hybrid species may have a strong evolutionary potential once their admixed genomes have stabilized and incompatibilities have been purged. Yet, little is known about how such hybrid lineages evolve at the genomic level following their formation, in particular the characteristics of their adaptive potential, i.e. constraints and facilitations of diversification. Here we investigate how the Italian sparrow (Passer italiae), a homoploid hybrid species, has evolved and locally adapted to its variable environment. Using restriction site-associated DNA sequencing (RAD-seq) on several populations across the Italian peninsula, we evaluate how genomic constraints and novel genetic variation have influenced population divergence and adaptation. We show that population divergence within this hybrid species has evolved in response to climatic variation. As in non-hybrid species, climatic differences may even reduce gene flow between populations, suggesting ongoing local adaptation. We report outlier genes associated with adaptation to climatic variation, known to be involved in beak morphology in other species. Most of the strongly divergent loci among Italian sparrow populations seem not to be differentiated between its parent species, the house and Spanish sparrow. Within the parental species, population divergence has occurred mostly in loci where different alleles segregate in the parent species, unlike in the hybrid, suggesting that novel combinations of parental alleles in the hybrid have not necessarily enhanced its evolutionary potential. Rather, our study suggests that constraints linked to incompatibilities may have restricted the evolution of this admixed genome, both during and after hybrid species formation.

scholarly journals Geographical variation in a quantitative character.

Genetics ◽  
1994 ◽  
Vol 136 (1) ◽  
pp. 361-381
Author(s):  
T Nagylaki
Keyword(s):  
Local Population ◽  
Weighted Average ◽  
Two Dimensions ◽  
Quantitative Character ◽  
Stabilizing Selection ◽  
Convergence To Equilibrium ◽  
Stepping Stone ◽  
Evolutionary Forces ◽  
Local Averages ◽  
Stepping Stone Model

Abstract A model for the evolution of the local averages of a quantitative character under migration, selection, and random genetic drift in a subdivided population is formulated and investigated. Generations are discrete and nonoverlapping; the monoecious, diploid population mates at random in each deme. All three evolutionary forces are weak, but the migration pattern and the local population numbers are otherwise arbitrary. The character is determined by purely additive gene action and a stochastically independent environment; its distribution is Gaussian with a constant variance; and it is under Gaussian stabilizing selection with the same parameters in every deme. Linkage disequilibrium is neglected. Most of the results concern the covariances of the local averages. For a finite number of demes, explicit formulas are derived for (i) the asymptotic rate and pattern of convergence to equilibrium, (ii) the variance of a suitably weighted average of the local averages, and (iii) the equilibrium covariances when selection and random drift are much weaker than migration. Essentially complete analyses of equilibrium and convergence are presented for random outbreeding and site homing, the Levene and island models, the circular habitat and the unbounded linear stepping-stone model in the diffusion approximation, and the exact unbounded stepping-stone model in one and two dimensions.

Hybridization in leopard frogs (Rana pipiens complex): terrestrial performance of newly metamorphosed hybrid and parental genotypes in field enclosures

2001 ◽  
Vol 79 (9) ◽  
pp. 1552-1558 ◽  
Author(s):  
Matthew J Parris
Keyword(s):  
Growth Rates ◽  
Life Histories ◽  
Parental Species ◽  
Natural Populations ◽  
Life Cycles ◽  
Natural Hybridization ◽  
Evolutionary Potential ◽  
Leopard Frogs ◽  
Rana Blairi ◽  
Advanced Generation

Terrestrial ecology has been largely neglected in the study of amphibian life histories because it is difficult to manipulate most species during the terrestrial stage. I examined the terrestrial performance of Rana blairi, Rana sphenocephala, and four hybrid (two F1 and two advanced generation) genotypes in replicated experimental enclosures to test for differences in traits related to juvenile terrestrial fitness. I produced all genotypes by means of artificial fertilizations using frogs collected from natural populations in central Missouri, and juvenile frogs were obtained from larvae reared in experimental ponds. Following metamorphosis, froglets were raised in single-genotype groups in terrestrial enclosures through the first overwintering. The proportion surviving did not vary among genotypes, but the power to detect significant differences was low. F1 hybrid genotypes BS and SB demonstrated significantly higher growth rates than either parental species or advanced-generation hybrid genotypes. Observation of growth rates of advanced-generation hybrids equal to those of the parental species, and heterosis in F1 hybrids for growth rate, suggests that natural hybridization between R. blairi and R. sphenocephala can produce novel and relatively fit hybrid genotypes. Direct measurement of multiple fitness components for hybrid and parental genotypes is critical for assessing the evolutionary potential of natural hybridization in organisms with complex life cycles.

scholarly journals Characterisation of Asian Snakehead MurrelChanna striata(Channidae) in Malaysia: An Insight into Molecular Data and Morphological Approach

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Li Min Song ◽  
Kaviarasu Munian ◽  
Zulkafli Abd Rashid ◽  
Subha Bhassu
Keyword(s):  
Molecular Data ◽  
Peninsular Malaysia ◽  
Population Divergence ◽  
Phenotypic Variance ◽  
Market Demand ◽  
Evolutionary Forces ◽  
Gene Coi ◽  
Identification Of Species ◽  
Conservation Assessments ◽  
Divergence Pattern

Conservation is imperative for the Asian snakeheadsChanna striata, as the species has been overfished due to its high market demand. Using maternal markers (mitochondrial cytochromecoxidase subunit 1 gene (COI)), we discovered that evolutionary forces that drove population divergence did not show any match between the genetic and morphological divergence pattern. However, there is evidence of incomplete divergence patterns between the Borneo population and the populations from Peninsular Malaysia. This supports the claim of historical coalescence ofC. striataduring Pleistocene glaciations. Ecological heterogeneity caused high phenotypic variance and was not correlated with genetic variance among the populations. Spatial conservation assessments are required to manage different stock units. Results on DNA barcoding show no evidence of cryptic species inC. striatain Malaysia. The newly obtained sequences add to the database of freshwater fish DNA barcodes and in future will provide information relevant to identification of species.

scholarly journals The coevolution of adult body mass and excretion rate between genetically size-divergent brook trout populations

2019 ◽  
Vol 76 (3) ◽  
pp. 438-446 ◽  
Author(s):  
Stéphanie Guernon ◽  
Matthew C. Yates ◽  
Dylan J. Fraser ◽  
Alison M. Derry
Keyword(s):  
Body Mass ◽  
Brook Trout ◽  
Excretion Rate ◽  
Common Garden ◽  
Population Divergence ◽  
Mass Energy ◽  
Maternal Factors ◽  
Mass Distributions ◽  
Adult Body Mass ◽  
Adult Body

We tested if there was a difference in mass-specific excretion rate between two genetically size-divergent brook trout (Salvelinus fontinalis) populations that can be accounted for by genetic/maternal factors. We conducted laboratory-based common garden experimentation using F1 generation fish, with five to seven families per population at two ages (0.5 year juveniles and 1.5 years adults). We found that genetic/maternal differences in excretion rate on a per gram basis coevolve with genetic divergence in adult body mass between the populations. However, this coevolution has also resulted in no net difference in excretion rate between populations when differences in adult body mass were accounted for. Uncertainty in census estimates and variation in body mass distributions created substantial variation in extrapolated whole-population excretion estimates. No other studies to our knowledge have tested for genetic/maternal divergence in excretion rate between genetically size-divergent fish populations. Genetically based population divergence in body mass, energy allocation in reproduction, and mass-specific excretion rate in the brook trout was likely a result of selection associated with differences in the availability of overwintering habitat between streams.

Effect of Phosphate and Silica on the Rate of Crystallization of Sucrose

2005 ◽  
Vol 1 (5) ◽  
Author(s):  
Ms. Aamarpali Ratna Puri ◽  
S. Kaur
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Mother Liquor ◽  
Crystal Surface ◽  
Mass Transfer Process ◽  
Sugar Solution ◽  
Local Conditions ◽  
Concentration Difference ◽  
Different Temperatures ◽  
Sucrose Crystals

Sucrose Crystallization is a mass transfer process. Sucrose molecule's migration from solution to crystal is driven by concentration difference between the mother liquor and the crystal surface; the coefficient of super saturation is the most important parameter for the process. Supersaturation of sugar solution depends on the purity and brix of the mother liquor. It has large influence on product's quantity and quality (crystal yield, crystal size and size distribution) and on the cost of production i.e output/hour and energy consumption. However there is still no generally applicable theory, which permits an accurate prediction of the effects of all the factors that govern the industrial processes of crystallization from solution. The crystal growth depends on the viscosity, which further depends on the nature and amount of impurities. If the local conditions are favourable, localized layers of molecules of impurity can statistically remain on the surface for a period of time. On the other hand, if the interaction between the impurity and the layer is weak, then there will be competition between impurity and sucrose molecules thus affecting the sucrose crystal growth rate. In the present study, the growth rate of sugar crystals was studied, using two-litre automatic laboratory vacuum pan, under controlled conditions in the presence of impurities. The effect of phosphate and silica (adding one at time) on the growth rate of sugar crystals was studied at two different temperatures 328 and 338K and with two different seed sizes of sucrose (850 and 600µm). The growth rate was studied at two degrees of supersaturation (1.10 and 1.15). The growth rate of sucrose crystals (with or without added impurities) showed significant increase with the 10°C rise in temperature. The growth rate of sucrose crystals increased with the increase in the level of phosphate but decreased with the increase in the level of silica in sugar solution.

CHANGES IN ANTIOXIDANT ISOZYMES AS A BIOMARKER FOR CHARACTERIZING HIGH TEMPERATURE STRESS TOLERANCE IN RICE (ORYZA SATIVA L.) SPIKELETS

2012 ◽  
Vol 49 (1) ◽  
pp. 53-73 ◽  
Author(s):  
SMRUTI DAS ◽  
P. KRISHNAN ◽  
MONALISA NAYAK ◽  
B. RAMAKRISHNAN
Keyword(s):  
High Temperature ◽  
Stress Tolerance ◽  
Temperature Stress ◽  
Oryza Sativa L ◽  
High Temperature Stress ◽  
Spikelet Sterility ◽  
Antioxidant Metabolism ◽  
Different Temperatures ◽  
Temperature Exposure

SUMMARYHigh temperature stress at flowering can adversely affect rice yield, largely due to failure of fertilization. Oxidative damage can be a major reason inducing spikelet sterility in rice. In the present study, the effect of high temperatures on antioxidant metabolism in rice spikelets was characterised using nine different genotypes. Exposure to different temperatures at flowering stage revealed significant differences among various antioxidant enzymes in spikelets, both quantitatively and qualitatively. Spikelets of susceptible genotypes withstood temperature stress of up to 35 °C, those of moderately tolerant between 35 °C and 38 °C and those of tolerant genotypes up to 40 °C. Presence or absence, and changes in the isozyme intensities were consistent with alterations in their activities. Superoxide dismutase (SOD) isozymes II and III were present after exposure at 30 °C and 35 °C, while SOD I appeared above 40°C. Intensities of catalase isozymes I and III and the only isozyme of ascorbate peroxidase altered, while the only isozyme of guaical peroxidase and two (III and IV) of the four isozymes of catechol peroxidase disappeared after high temperature exposure of 45 °C. Thus, this work provides an evidence of the role of antioxidant metabolism in spikelets under high temperature stress conditions. Hence, changes in antioxidant isozymes in rice spikelets can be used as a biomarker for characterizing high temperature stress tolerance in rice spikelets.

scholarly journals Spatial resource heterogeneity creates local hotspots of evolutionary potential

2017 ◽  
Author(s):  
Emily Dolson ◽  
Charles Ofria
Keyword(s):  
Explanatory Power ◽  
Biological Evolution ◽  
Biological Data ◽  
Heterogeneous Environments ◽  
Digital Evolution ◽  
Resource Heterogeneity ◽  
Evolutionary Potential ◽  
Local Conditions ◽  
Local Diversity ◽  
Novel Traits

AbstractDo local conditions influence evolution’s ability to produce new traits? Biological data demonstrate that evolutionary processes can be profoundly influenced by local conditions. However, the evolution of novel traits has not been addressed in this context, owing in part to the challenges of performing the necessary experiments with natural organisms. We conduct in silico experiments with the Avida Digital Evolution Platform to address this question. We created eight different spatially heterogeneous environments and ran 100 replicates in each. Within each environment, we examined the distribution of locations where nine different focal traits first evolved. Using spatial statistics methods, we identified regions within each environment that had significantly elevated probabilities of containing the first organism with a given trait (i.e. hotspots of evolutionary potential). Having demonstrated the presence of many such hotspots, we explored three potential mechanisms that could drive the formation of these patterns: proximity of specific resources, variation in local diversity, and variation in the sequence of locations the members of an evolutionary lineage occupy. Resource proximity and local diversity appear to have minimal explanatory power. Lineage paths through space, however, show some promising preliminary trends. If we can understand the processes that create evolutionary hotspots, we will be able to craft environments that are more effective at evolving targeted traits. This capability would be useful both to evolutionary computation, and to efforts to guide biological evolution.

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