scholarly journals Community rescue in experimental phytoplankton communities facing severe herbicide pollution

2018 ◽  
Author(s):  
Fugère V. ◽  
Hébert M.-P ◽  
Costa N.B. ◽  
Xu C.C.Y. ◽  
Barrett R.D.H. ◽  
...  
Keyword(s):  
Biodiversity Loss ◽  
Community Resistance ◽  
Community Biomass ◽  
Community Turnover ◽  
Evolutionary Rescue ◽  
Phytoplankton Communities ◽  
Sublethal Stress ◽  
Large Populations ◽  
Sublethal Doses ◽  
Prior Stress

AbstractEvolutionary rescue occurs when adaptation prevents local extinction in deteriorating environments. Laboratory experiments with microorganisms have shown that the likelihood of evolutionary rescue is greatest in large populations that have previously experienced sublethal doses of stress. To assess this result in natural communities, we conducted a mesocosm experiment with semi-natural phytoplankton communities exposed to glyphosate, a widely used herbicide. We tested whether community biomass and pre-exposure to sublethal stress would facilitate community rescue after severe contamination. Exposure to sublethal stress, but not community biomass, facilitated rescue significantly–even though it led to biodiversity loss. Furthermore, glyphosate had modest effects on community composition, suggesting that community resistance to glyphosate was primarily driven by changes in resistance within taxa, not by community turnover. Our results expand the scope of community evolutionary rescue theory to complex ecosystems and confirm that prior stress exposure is a key predictor of rescue.

scholarly journals Soft selective sweeps in evolutionary rescue

2016 ◽  
Author(s):  
Benjamin A. Wilson ◽  
Pleuni S. Pennings ◽  
Dmitri A. Petrov
Keyword(s):  
Drug Resistance ◽  
Population Genetics ◽  
Population Genetic ◽  
Genetic Adaptation ◽  
Selective Sweeps ◽  
Adaptive Mutations ◽  
Evolutionary Rescue ◽  
Large Populations ◽  
Genetic Signatures ◽  
Soft Selective Sweeps

AbstractEvolutionary rescue occurs when a population that is declining in size because of an environmental change is rescued by genetic adaptation. Evolutionary rescue is an important phenomenon at the intersection of ecology and population genetics. While most population genetic models of evolutionary rescue focus on estimating the probability of rescue, we focus on whether one or more adaptive lineages contribute to evolutionary rescue. We find that when evolutionary rescue is likely, it is often driven by soft selective sweeps where multiple adaptive mutations spread through the population simultaneously. We give full analytic results for the probability of evolutionary rescue and the probability that evolutionary rescue occurs via soft selective sweeps in our model. We expect that these results will find utility in understanding the genetic signatures associated with various evolutionary rescue scenarios in large populations, such as the evolution of drug resistance in viral, bacterial, or eukaryotic pathogens.

scholarly journals Shared ancestry influences community stability by altering competitive interactions: evidence from a laboratory microcosm experiment using freshwater green algae

2013 ◽  
Vol 280 (1768) ◽  
pp. 20131548 ◽  
Author(s):  
Patrick A. Venail ◽  
Markos A. Alexandrou ◽  
Todd H. Oakley ◽  
Bradley J. Cardinale
Keyword(s):  
Related Species ◽  
Temporal Stability ◽  
Biodiversity Loss ◽  
Competitive Interactions ◽  
Ecological Communities ◽  
Freshwater Microalgae ◽  
Community Biomass ◽  
Shared Ancestry ◽  
The Stability ◽  
The Impact

The impact of biodiversity on the stability of ecological communities has been debated among biologists for more than a century. Recently summarized empirical evidence suggests that biodiversity tends to enhance the temporal stability of community-level properties such as biomass; however, the underlying mechanisms driving this relationship remain poorly understood. Here, we report the results of a microcosm study in which we used simplified systems of freshwater microalgae to explore how the phylogenetic relatedness of species influences the temporal stability of community biomass by altering the nature of their competitive interactions. We show that combinations of two species that are more evolutionarily divergent tend to have lower temporal stability of biomass. In part, this is due to negative ‘selection effects’ in which bicultures composed of distantly related species are more likely to contain strong competitors that achieve low biomass. In addition, bicultures of distantly related species had on average weaker competitive interactions, which reduced compensatory dynamics and decreased the stability of community biomass. Our results demonstrate that evolutionary history plays a key role in controlling the mechanisms, which give rise to diversity–stability relationships. As such, patterns of shared ancestry may help us predict the ecosystem-level consequences of biodiversity loss.

scholarly journals Evolutionary Rescue as a Mechanism Allowing a Clonal Grass to Adapt to Novel Climates

2021 ◽  
Vol 12 ◽  
Author(s):  
Zuzana Münzbergová ◽  
Vigdis Vandvik ◽  
Věroslava Hadincová
Keyword(s):  
Climate Change ◽  
Plant Traits ◽  
Climate Extremes ◽  
Biodiversity Loss ◽  
Model Systems ◽  
Necessary Condition ◽  
Transplant Experiment ◽  
Reciprocal Transplant Experiment ◽  
Term Selection ◽  
Evolutionary Rescue

Filing gaps in our understanding of species' abilities to adapt to novel climates is a key challenge for predicting future range shifts and biodiversity loss. Key knowledge gaps are related to the potential for evolutionary rescue in response to climate, especially in long-lived clonally reproducing species. We illustrate a novel approach to assess the potential for evolutionary rescue using a combination of reciprocal transplant experiment in the field to assess performance under a changing climate and independent growth chamber assays to assess growth- and physiology-related plant trait maxima and plasticities of the same clones. We use a clonal grass, Festuca rubra, as a model species. We propagated individual clones and used them in a transplant experiment across broad-scale temperature and precipitation gradients, simulating the projected direction of climate change in the region. Independent information on trait maxima and plasticities of the same clones was obtained by cultivating them in four growth chambers representing climate extremes. Plant survival was affected by interaction between plant traits and climate change, with both trait plasticities and maxima being important for adaptation to novel climates. Key traits include plasticity in extravaginal ramets, aboveground biomass, and osmotic potential. The direction of selection in response to a given climatic change detected in this study mostly contradicted the natural trait clines indicating that short-term selection pressure as identified here does not match long-term selection outcomes. Long-lived clonal species exposed to different climatic changes are subjected to consistent selection pressures on key traits, a necessary condition for adaptation to novel conditions. This points to evolutionary rescue as an important mechanism for dealing with climate change in these species. Our experimental approach may be applied also in other model systems broadening our understanding of evolutionary rescue. Such knowledge cannot be easily deduced from observing the existing field clines.

scholarly journals Diversification or collapse of self-incompatibility haplotypes as outcomes of evolutionary rescue

2019 ◽  
Author(s):  
Alexander Harkness ◽  
Emma E. Goldberg ◽  
Yaniv Brandvain
Keyword(s):  
Gene Conversion ◽  
Balancing Selection ◽  
Markov Chain Model ◽  
Haplotype Diversity ◽  
Allelic Polymorphism ◽  
Chain Model ◽  
Self Incompatibility ◽  
Evolutionary Rescue ◽  
Large Populations ◽  
Incompatibility Locus

AbstractSelf-incompatibility systems in angiosperms are exemplars of extreme allelic polymorphism maintained by long-term balancing selection. Pollen that shares an allele with the pollen recipient at the self-incompatibility locus is rejected, and this rejection favors rare alleles as well as preventing self-fertilization. Advances in molecular genetics reveal that an ancient, deeply conserved, and well-studied incompatibility system functions through multiple tightly linked genes encoding separate pollen-expressed F-box proteins and pistil-expressed ribonucleases. We show that certain recombinant haplotypes at the incompatibility locus can drive collapse in the number of incompatibility types. We use a modified evolutionary rescue model to calculate the relative probabilities of increase and collapse in number of incompatibility types given the initial collection of incompatibility haplotypes and the population rate of gene conversion. We find that expansion in haplotype number is possible when population size or the rate of gene conversion is large, but large contractions are likely otherwise. By iterating a Markov chain model derived from these expansion and collapse probabilities, we find that a stable haplotype number distribution in the realistic range of 10–40 is possible under plausible parameters. However, small or moderate-sized populations should be susceptible to substantial additional loss of haplotypes beyond those lost by chance during bottlenecks. The same processes that can generate many incompatibility haplotypes in large populations may therefore be crushing haplotype diversity in smaller populations.

scholarly journals Evolutionary rescue and the limits of adaptation

2013 ◽  
Vol 368 (1610) ◽  
pp. 20120080 ◽  
Author(s):  
Graham Bell
Keyword(s):  
Genetic Variation ◽  
Natural Selection ◽  
Relative Fitness ◽  
Population Declines ◽  
Genetic Constraints ◽  
Evolutionary Rescue ◽  
Large Populations ◽  
Effective Selection ◽  
The Cost ◽  
Number Of Individuals

Populations subject to severe stress may be rescued by natural selection, but its operation is restricted by ecological and genetic constraints. The cost of natural selection expresses the limited capacity of a population to sustain the load of mortality or sterility required for effective selection. Genostasis expresses the lack of variation that prevents many populations from adapting to stress. While the role of relative fitness in adaptation is well understood, evolutionary rescue emphasizes the need to recognize explicitly the importance of absolute fitness. Permanent adaptation requires a range of genetic variation in absolute fitness that is broad enough to provide a few extreme types capable of sustained growth under a stress that would cause extinction if they were not present. This principle implies that population size is an important determinant of rescue. The overall number of individuals exposed to selection will be greater when the population declines gradually under a constant stress, or is progressively challenged by gradually increasing stress. In gradually deteriorating environments, survival at lethal stress may be procured by prior adaptation to sublethal stress through genetic correlation. Neither the standing genetic variation of small populations nor the mutation supply of large populations, however, may be sufficient to provide evolutionary rescue for most populations.

scholarly journals Evolutionary rescue: an emerging focus at the intersection between ecology and evolution

2013 ◽  
Vol 368 (1610) ◽  
pp. 20120404 ◽  
Author(s):  
Andrew Gonzalez ◽  
Ophélie Ronce ◽  
Regis Ferriere ◽  
Michael E. Hochberg
Keyword(s):  
Environmental Change ◽  
Evolutionary Dynamics ◽  
Population Decline ◽  
Biodiversity Loss ◽  
Relative Fitness ◽  
Adaptation To Climate Change ◽  
Practical Concern ◽  
Evolutionary Rescue ◽  
Declining Populations ◽  
Short Time

There is concern that the rate of environmental change is now exceeding the capacity of many populations to adapt. Mitigation of biodiversity loss requires science that integrates both ecological and evolutionary responses of populations and communities to rapid environmental change, and can identify the conditions that allow the recovery of declining populations. This special issue focuses on evolutionary rescue (ER), the idea that evolution might occur sufficiently fast to arrest population decline and allow population recovery before extinction ensues. ER emphasizes a shift to a perspective on evolutionary dynamics that focuses on short time-scales, genetic variants of large effects and absolute rather than relative fitness. The contributions in this issue reflect the state of field; the articles address the latest conceptual developments, and report novel theoretical and experimental results. The examples in this issue demonstrate that this burgeoning area of research can inform problems of direct practical concern, such as the conservation of biodiversity, adaptation to climate change and the emergence of infectious disease. The continued development of research on ER will be necessary if we are to understand the extent to which anthropogenic global change will reduce the Earth's biodiversity.

scholarly journals Evolutionary rescue and adaptation to abrupt environmental change depends upon the history of stress

2013 ◽  
Vol 368 (1610) ◽  
pp. 20120079 ◽  
Author(s):  
Andrew Gonzalez ◽  
Graham Bell
Keyword(s):  
Environmental Change ◽  
Salt Concentration ◽  
Quadratic Function ◽  
Closely Related Species ◽  
Evolutionary Rescue ◽  
Low Salt ◽  
Large Populations ◽  
Declining Populations ◽  
History Of ◽  
Sublethal Concentrations

Whether evolution will be rapid enough to rescue declining populations will depend upon population size, the supply of genetic variation, the degree of maladaptation and the historical direction of selection. We examined whether the level of environmental stress experienced by a population prior to abrupt environmental change affects the probability of evolutionary rescue (ER). Hundreds of populations of two species of yeast, Saccharomyces cerevisiae and Saccharomyces paradoxus were exposed to a range of sublethal concentrations of salt for approximately a hundred generations before transfer to a concentration of salt lethal to the ancestor (150 g l –1 NaCl). The fitness of surviving populations of both species was a quadratic function of yield: fitness was greatest for large populations that had been selected on low salt concentrations (less than 20 g l −1 NaCl) and small populations that had adapted to high salt (more than 80 g l −1 NaCl). However, differences occurred between species in the probability of ER. The frequency of ER was positively correlated with salt concentration for S. cerevisiae, but negatively correlated with salt concentration in S. paradoxus . These results not only demonstrate that past environmental conditions can determine the probability of ER after abrupt environmental change, but also suggest that there may even be differences between closely related species that are worth further exploration.

scholarly journals Driven to Extinction: On the Probability of Evolutionary Rescue from Sex-Ratio Meiotic Drive

2015 ◽  
Author(s):  
Robert Unckless ◽  
Andrew Clark
Keyword(s):  
Sex Ratio ◽  
Sex Chromosome ◽  
Extinction Risk ◽  
Meiotic Drive ◽  
Extinction Time ◽  
Weak Selection ◽  
Evolutionary Rescue ◽  
Large Populations ◽  
Opposite Sex ◽  
Mean Fitness

Many evolutionary processes result in sufficiently low mean fitness that they pose a risk of species extinction. Sex-ratio meiotic drive was recognized by W.D. Hamilton (1967) to pose such a risk, because as the driving sex chromosome becomes common, the opposite sex becomes rare. We expand on Hamilton’s classic model by allowing for the escape from extinction due to evolution of suppressors of X and Y drivers. We explore differences in the two systems in their probability of escape from extinction. Several novel conclusions are evident, including a) that extinction time scales approximately with the log of population size so that even large populations may go extinct quickly, b) extinction risk is driven by the relationship between female fecundity and drive strength, c) anisogamy and the fact that X and Y drive result in sex ratios skewed in opposite directions, mean systems with Y drive are much more likely to go extinct than those with X drive, and d) suppressors are most likely to become established when the strength of drive is intermediate, since weak drive leads to weak selection for suppression and strong drive leads to rapid extinction.

Morphogenetic machines revealed: Microscopy of living cells in the embryo of the frog, Xenopus laevis

1993 ◽  
Vol 51 ◽  
pp. 172-173
Author(s):  
Ray Keller
Keyword(s):  
Image Processing ◽  
Fluorescent Dyes ◽  
Cell Movement ◽  
Living Cells ◽  
Ease Of Use ◽  
Low Light ◽  
Amphibian Embryo ◽  
Large Populations ◽  
Light Fluorescence ◽  
Video Image Processing

The amphibian embryo offers advantages of size, availability, and ease of use with both microsurgical and molecular methods in the analysis of fundamental developmental and cell biological problems. However, conventional wisdom holds that the opacity of this embryo limits the use of methods in optical microscopy to resolve the cell motility underlying the major shape-generating processes in early development.These difficulties have been circumvented by refining and adapting several methods. First, methods of explanting and culturing tissues were developed that expose the deep, nonepithelial cells, as well as the superficial epithelial cells, to the view of the microscope. Second, low angle epi-illumination with video image processing and recording was used to follow patterns of cell movement in large populations of cells. Lastly, cells were labeled with vital, fluorescent dyes, and their behavior recorded, using low-light, fluorescence microscopy and image processing. Using these methods, the details of the cellular protrusive activity that drives the powerful convergence (narrowing)

Biodiversity Loss

1995 ◽  
Keyword(s):  
Biodiversity Loss
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