scholarly journals Selection on growth rate and local adaptation drive genomic adaptation during experimental range expansions in the protist Tetrahymena thermophila

2021 ◽  
Author(s):  
Felix Moerman ◽  
Emanuel A. Fronhofer ◽  
Florian Altermatt ◽  
Andreas Wagner
Keyword(s):  
Growth Rate ◽  
Local Adaptation ◽  
Tetrahymena Thermophila ◽  
Experimental Range ◽  
Genomic Adaptation

scholarly journals Selection on growth rate and local adaptation drive genomic adaptation during experimental range expansions in the protist Tetrahymena thermophila

2021 ◽  
Author(s):  
Felix Moerman ◽  
Emanuel A. Fronhofer ◽  
Florian Altermatt ◽  
Andreas Wagner
Keyword(s):  
Gene Flow ◽  
Sexual Reproduction ◽  
Range Expansion ◽  
De Novo ◽  
Tetrahymena Thermophila ◽  
Ph Gradient ◽  
Genetic Changes ◽  
Experimental Range ◽  
Standing Variation ◽  
Genomic Adaptation

AbstractPopulations that expand their range can undergo rapid evolutionary adaptation, which can be aided or hindered by sexual reproduction and gene flow. Little is known about the genomic causes and consequences of such adaptation. We studied genomic adaptation during experimental range expansions of the protist Tetrahymena thermophila in landscapes with a uniform environment or a pH-gradient, both in the presence and absence of gene flow and sexual reproduction. We used pooled genome sequencing to identify genes subject to selection caused by the expanding range and by the pH-gradient. Adaptation to the range expansion affected genes involved in cell divisions and DNA repair, whereas adaptation to the pH gradient additionally affected genes involved in ion balance, and oxidoreductase reactions. These genetic changes may result from selection on growth and adaptation to low pH. Sexual reproduction affected both de novo mutation and standing genetic variation, whereas gene flow and the presence of a pH-gradient affected only standing variation. Sexual reproduction may have aided genetic adaptation during range expansion, but only in the absence of gene flow, which may have swamped expanding populations with maladapted alleles.

scholarly journals Differential Growth of and Nanoscale TiO2Accumulation in Tetrahymena thermophila by Direct Feeding versus Trophic Transfer from Pseudomonas aeruginosa

2013 ◽  
Vol 79 (18) ◽  
pp. 5616-5624 ◽  
Author(s):  
Randall E. Mielke ◽  
John H. Priester ◽  
Rebecca A. Werlin ◽  
Jeff Gelb ◽  
Allison M. Horst ◽  
...  
Keyword(s):  
Growth Rate ◽  
Pseudomonas Aeruginosa ◽  
Tetrahymena Thermophila ◽  
Food Vacuole ◽  
Trophic Levels ◽  
Differential Growth ◽  
Feeding Mode ◽  
Content Type ◽  
Route Of Exposure ◽  
Population Yield

ABSTRACTNanoscale titanium dioxide (TiO2) is increasingly used in consumer goods and is entering waste streams, thereby exposing and potentially affecting environmental microbes. Protozoans could either take up TiO2directly from water and sediments or acquire TiO2during bactivory (ingestion of bacteria) of TiO2-encrusted bacteria. Here, the route of exposure of the ciliated protozoanTetrahymena thermophilato TiO2was varied and the growth of, and uptake and accumulation of TiO2by,T. thermophilawere measured. While TiO2did not affectT. thermophilaswimming or cellular morphology, direct TiO2exposure in rich growth medium resulted in a lower population yield. When TiO2exposure was by bactivory ofPseudomonas aeruginosa, theT. thermophilapopulation yield and growth rate were lower than those that occurred during the bactivory of non-TiO2-encrusted bacteria. Regardless of the feeding mode,T. thermophilacells internalized TiO2into their food vacuoles. Biomagnification of TiO2was not observed; this was attributed to the observation that TiO2appeared to be unable to cross the food vacuole membrane and enter the cytoplasm. Nevertheless, our findings imply that TiO2could be transferred into higher trophic levels within food webs and that the food web could be affected by the decreased growth rate and yield of organisms near the base of the web.

scholarly journals Convergent local adaptation in size and growth rate but not metabolic rate in a pair of parapatric Orthoptera species

2014 ◽  
Vol 113 (1) ◽  
pp. 123-135 ◽  
Author(s):  
Niki A. Minards ◽  
Steven A. Trewick ◽  
A. Jonathan R. Godfrey ◽  
Mary Morgan-Richards
Keyword(s):  
Growth Rate ◽  
Metabolic Rate ◽  
Local Adaptation

scholarly journals The genomic basis of domestic colonisation and dispersal in Chagas disease vectors

2021 ◽  
Author(s):  
Luis E Hernandez-Castro ◽  
Anita G Villacís ◽  
Arne Jacobs ◽  
Bachar Cheaib ◽  
Casey C Day ◽  
...  
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Local Adaptation ◽  
Chagas Disease ◽  
Regional Scale ◽  
Landscape Genomics ◽  
Human Habitat ◽  
Rhodnius Ecuadoriensis ◽  
Genomic Adaptation ◽  
Domestic Setting

AbstractThe biology of vector adaptation to the human habitat remains poorly understood for many arthropod-borne diseases but underpins effective and sustainable disease control. We adopted a landscape genomics approach to investigate gene flow, signatures of local adaptation, and drivers of population structure among multiple linked wild and domestic population pairs in Rhodnius ecuadoriensis, an important vector of Chagas Disease. Evidence of high triatomine gene flow (FST) between wild and domestic ecotopes at sites throughout the study area indicate insecticide-based control will be hindered by constant re-infestation of houses. Genome scans revealed genetic loci with strong signal of local adaptation to the domestic setting, which we mapped to annotated regions in the Rhodnius prolixus genome. Our landscape genomic mixed effects models showed Rhodnius ecuadoriensis population structure and connectivity is driven by landscape elevation at a regional scale. Our ecologically- and spatially-explicit vector dispersal model enables targeted vector control and recommends spatially discrete, periodic interventions to local authorities as more efficacious than current, haphazard approaches. In tandem, evidence for parallel genomic adaptation to colonisation of the domestic environment at multiple sites sheds new light on the evolutionary basis of adaptation to the human host in arthropod vectors.

scholarly journals Temperature affects the repeatability of evolution in the microbial eukaryote Tetrahymena thermophila

2020 ◽  
Author(s):  
Jason A Tarkington ◽  
Rebecca Zufall
Keyword(s):  
Growth Rate ◽  
High Temperature ◽  
Tetrahymena Thermophila ◽  
Correlated Responses ◽  
Trade Offs ◽  
Evolutionary Trajectories ◽  
Two Temperatures ◽  
Higher Temperature ◽  
Lower Temperature

AbstractEvolutionary biologists have long sought to understand what factors affect the repeatability of adaptive outcomes. To better understand the role of temperature in determining the repeatability of adaptive trajectories, we evolved populations of different genotypes of the ciliate Tetrahymena thermophila at low and high temperatures and followed changes in growth rate over 4,000 generations. As expected, growth rate increased with a decelerating rate for all populations; however, there were differences in the patterns of evolution at the two temperatures. The growth rates of the different genotypes converged as evolution proceeded at both temperatures, but this convergence was quicker at the higher temperature. Likewise, we found greater repeatability of evolution, in terms of change in growth rate, among replicates of the same genotype at the higher temperature. Finally, we found no evidence of trade-offs in fitness between temperatures, but did observe asymmetry in the correlated responses, whereby evolution in a high temperature increases growth rate at the lower temperature significantly more than the reverse. These results demonstrate the importance of temperature in determining the repeatability of evolutionary trajectories.

scholarly journals Experimental multi-species microbial (co)evolution results in local maladaptation

2020 ◽  
Author(s):  
Meaghan Castledine ◽  
Daniel Padfield ◽  
Angus Buckling
Keyword(s):  
Growth Rate ◽  
Local Adaptation ◽  
Growth Rates ◽  
Sympatric Species ◽  
The Other ◽  
Competitive Interactions ◽  
Community Stability ◽  
Community Members ◽  
Microbial Species ◽  
Species Pairs

AbstractInterspecific coevolutionary interactions can result in rapid biotic adaptation, but most studies have focused only on species pairs. Here, we (co)evolved five microbial species in replicate polycultures and monocultures and quantified local adaptation. Specifically, growth rate assays were used to determine adaptations of each species’ populations to (1) the presence of the other four species in general and (2) sympatric vs allopatric communities. We found no evidence for general biotic adaptation: ancestral, polyculture- and monoculture-evolved populations did not have significantly different growth rates when measured within communities. However, 4/5 species’ growth rates were significantly lower within the community they evolved in. This “local maladaptation” suggests that species evolved increased competitive interactions to sympatric species’ populations. This increased competition did not affect community stability or productivity. Our results suggest that (co)evolution within communities can increase competitive interactions that are specific to (co)evolved community members.

scholarly journals Data-driven, participatory characterization of traditional farmer varieties discloses teff (Eragrostis tef) adaptive and breeding potential under current and future climates

2021 ◽  
Author(s):  
Aemiro Bezabih Woldeyohannes ◽  
Sessen Daniel Iohannes ◽  
Mara Miculan ◽  
Leonardo Caproni ◽  
Jemal Seid Ahmed ◽  
...  
Keyword(s):  
Local Adaptation ◽  
Genome Wide Association Study ◽  
Cropping Systems ◽  
Farming Systems ◽  
Climate Science ◽  
Eragrostis Tef ◽  
Smallholder Farming ◽  
Breeding Potential ◽  
A Genome ◽  
Genomic Adaptation

In smallholder farming systems, traditional farmer varieties of neglected and underutilized crops species (NUS) support the livelihoods of millions of growers and consumers. NUS combine cultural and agronomic value with local adaptation, and call for transdisciplinary methods to evaluate their breeding potential. Here, we combined farmers' traditional knowledge, genomics, and climate science to characterize 366 Ethiopian teff (Eragrostis tef) farmer varieties and breeding materials. We found that teff genetic diversity in Ethiopia could be organized in six genetic clusters associated to climate variation on the landscape. A participatory evaluation conducted in collaboration with local farmers could consistently identify best performing varieties and inform a genome wide association study to identify candidate genes for farmers' appreciation, phenology, yield, and local adaptation. By modelling the genomic adaptation of teff to current and projected climates, we identified an area around lake Tana where teff cropping will be most vulnerable to climate change. Our results show that transdisciplinary approaches may efficiently propel untapped NUS farmer varieties into modern breeding to foster more resilient and sustainable cropping systems

The regulation of amounts and proportions of genetic elements in the macronuclei of Tetrahymena thermophila strains of diverse karyotype

1979 ◽  
Vol 40 (1) ◽  
pp. 111-123
Author(s):  
H.M. Seyfert ◽  
R.M. Preparata
Keyword(s):  
Growth Rate ◽  
Dna Content ◽  
Tetrahymena Thermophila ◽  
Gene Dosage ◽  
Size Class ◽  
Maximal Density ◽  
Genetic Elements ◽  
Dna Contents ◽  
Cell Volumes

Measurements of the micronuclear DNA content of clones with assumed different degrees of micronuclear ploidy confirmed the triploid nature of one clone. The micronuclear DNA content of a presumptive haploid clone was found to be slightly higher than expected, whereas one of two aneuploid clones had an unexpectedly low micronuclear DNA content. The macronuclear DNA content of cells with macronuclei which had developed from triploid, diploid and probably haploid and aneuploid macronuclear-Anlagen is very similar. Specifically, the smallest individual macronuclear DNA contents are consistently found within the same size class in all clones tested. Cell volumes, RNA and protein contents are alike in all clones tested. Only the growth rate and maximal density reached of one out of two aneuploid clones is reduced in comparison with the very similar other clones. The results are discussed with reference to the regulation of macronuclear DNA content, and to the compensation of gene-dosage.

The threshold energy for atom displacement in fcc metals

1990 ◽  
Vol 48 (4) ◽  
pp. 530-531
Author(s):  
Wilfried Sigle ◽  
Matthias Hohenstein ◽  
Alfred Seeger
Keyword(s):  
Growth Rate ◽  
Elevated Temperatures ◽  
Threshold Energy ◽  
Dislocation Loops ◽  
Absolute Minimum ◽  
Voltage Electron ◽  
Atom Displacement ◽  
Electron Microscopes ◽  
Fcc Metal

Prolonged electron irradiation of metals at elevated temperatures usually leads to the formation of large interstitial-type dislocation loops. The growth rate of the loops is proportional to the total cross-section for atom displacement,which is implicitly connected with the threshold energy for atom displacement, Ed . Thus, by measuring the growth rate as a function of the electron energy and the orientation of the specimen with respect to the electron beam, the anisotropy of Ed can be determined rather precisely. We have performed such experiments in situ in high-voltage electron microscopes on Ag and Au at 473K as a function of the orientation and on Au as a function of temperature at several fixed orientations.Whereas in Ag minima of Ed are found close to <100>,<110>, and <210> (13-18eV), (Fig.1) atom displacement in Au requires least energy along <100>(15-19eV) (Fig.2). Au is thus the first fcc metal in which the absolute minimum of the threshold energy has been established not to lie in or close to the <110> direction.

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