scholarly journals Differential polysaccharide utilization is the basis for a nanohaloarchaeon : haloarchaeon symbiosis

2019 ◽  
Author(s):  
Violetta La Cono ◽  
Enzo Messina ◽  
Manfred Rohde ◽  
Erika Arcadi ◽  
Sergio Ciordia ◽  
...  
Keyword(s):  
Physical Contact ◽  
Food Chains ◽  
Carbon Turnover ◽  
Bet Hedging ◽  
Metabolic Potential ◽  
Hedging Strategy ◽  
Carbon Substrates ◽  
Microbial Carbon ◽  
Sugar Derivatives

AbstractNanohaloarchaeota, a clade of diminutive archaea, with small genomes and limited metabolic capabilities, are ubiquitous in hypersaline habitats, which they share with the extremely halophilic and phylogenetically distant euryarchaea. Some of these nanohaloarchaeota and euryarchaea appear to interact with each other. In this study, we investigate the genetic and physiological nature of their relationship. We isolated the nanohaloarchaeon Candidatus Nanohalobium constans LC1Nh and the haloarchaeon Halomicrobium sp. LC1Hm from a solar saltern, reproducibly co-cultivated these species, sequenced their genomes, and characterized their metabolic/trophic interactions. The nanohaloarchaeon is a magnesium-dependent aerotolerant heterotrophic anaerobe of the DPANN superphylum; it lacks respiratory complexes and its energy production relies on fermentative metabolism of sugar derivatives, obtained by depolymerizing alpha-glucans or by acquiring the chitin monomer N-acetylglucosamine from the chitinolytic haloarchaeal host. Halomicrobium is a member of the class Halobacteria and a chitinotrophic aerobe. The nanohaloarchaeon lacks key biosynthetic pathways and is likely to be provided with amino acids, lipids, nucleotides and cofactors via physical contact with its host Halomicrobium. In turn, the ability of Ca. Nanohalobium to hydrolyse alpha-glucans boosts the host’s growth in the absence of a chitin substrate. These findings suggest that at least some members of the nanohaloarchaea, previously considered ecologically unimportant given their limited metabolic potential, in fact may play significant roles in the microbial carbon turnover, food chains, and ecosystem function. The behaviour of Halomicrobium, which accommodates the colonization by Ca. Nanohalobium, can be interpreted as a bet-hedging strategy, maximizing its long-term fitness in a habitat where the availability of carbon substrates can vary both spatially and temporarily.

scholarly journals Temporal variability and cooperative breeding: testing the bet-hedging hypothesis in the acorn woodpecker

2015 ◽  
Vol 282 (1816) ◽  
pp. 20151742 ◽  
Author(s):  
Walter D. Koenig ◽  
Eric L. Walters
Keyword(s):  
Reproductive Success ◽  
Cooperative Breeding ◽  
Group Living ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Ecological Conditions ◽  
Variable Environments ◽  
Melanerpes Formicivorus ◽  
Mean Fitness

Cooperative breeding is generally considered an adaptation to ecological constraints on dispersal and independent breeding, usually due to limited breeding opportunities. Although benefits of cooperative breeding are typically thought of in terms of increased mean reproductive success, it has recently been proposed that this phenomenon may be a bet-hedging strategy that reduces variance in reproductive success (fecundity variance) in populations living in highly variable environments. We tested this hypothesis using long-term data on the polygynandrous acorn woodpecker ( Melanerpes formicivorus ). In general, fecundity variance decreased with increasing sociality, at least when controlling for annual variation in ecological conditions. Nonetheless, decreased fecundity variance was insufficient to compensate for reduced per capita reproductive success of larger, more social groups, which typically suffered lower estimated mean fitness. We did, however, find evidence that sociality in the form of larger group size resulted in increased fitness in years following a small acorn crop due to reduced fecundity variance. Bet-hedging, although not the factor driving sociality in general, may play a role in driving acorn woodpecker group living when acorns are scarce and ecological conditions are poor.

scholarly journals Individual reversible plasticity as a genotype‐level bet‐hedging strategy

2021 ◽  
Author(s):  
Thomas R. Haaland ◽  
Jonathan Wright ◽  
Irja I. Ratikainen
Keyword(s):  
Bet Hedging ◽  
Hedging Strategy

Shaping Monkey-Human Contact

1973 ◽  
Vol 36 (1) ◽  
pp. 235-243 ◽  
Author(s):  
Louis Aarons
Keyword(s):  
Behavior Therapy ◽  
Physical Contact ◽  
Human Relationship ◽  
Human Contact ◽  
Experimental Behavior ◽  
Long Term Studies

An empirically ordered sequence of 11 steps is described for the training of progressive increases in physical contact between monkeys and Es. The steps range from a point at which food is not accepted from E's hand, through the touching and petting of varied parts of the monkey's body, to the monkey climbing on or being held by E. Some illustrative data are presented and it is suggested that evaluation of the animal-human relationship is relevant to long-term studies in experimental behavior therapy.

Ecological succession as an aspect of structure in fossil communities

Paleobiology ◽  
1975 ◽  
Vol 1 (3) ◽  
pp. 238-257 ◽  
Author(s):  
Kenneth R. Walker ◽  
Leonard P. Alberstadt
Keyword(s):  
Environmental Changes ◽  
Food Chains ◽  
Short Term ◽  
Niche Specialization ◽  
Pattern Diversity ◽  
Physical Environments ◽  
Autogenic Succession ◽  
Succession Stage ◽  
Stratigraphic Sequences

Succession involves changes in a community through time, whether internally or externally controlled. As succession progresses, niche specialization, species diversity (variety and equitability), complexity of food chains, and pattern diversity increase; net production and species growth rate decrease. We apply the succession concept to three types of ancient community sequences: 1) fossil reefs (Ordovician—Cretaceous in age), 2) short-term successions occurring through thin stratigraphic intervals, and 3) long-term successions occurring through thicker stratigraphic intervals. Ancient reefs show four vertical zones: (1) a basal stabilization zone (autogenic), 2) the overlying colonization zone (autogenic, pioneer stage), 3) the diversification zone, the bulk of most reefs (diversification culminating in climax), and 4) the uppermost domination zone. The first three zones represent autogenic succession but the final stage may involve allogenic succession. Short-term succession usually occurs where periodic allogenic catastrophes wipe out the community which is rebuilt through autogenic succession. Opportunistic pioneer species are important and in our examples (Ordovician, Silurian, and Cretaceous) are species which pave soft substrata. Paleozoic strophomenid brachiopods filled this role, and inoceramid pelecypods served the function in the Mesozoic. The succession which begins with opportunists progresses to a climax community of equilibrists. Repetition of catastrophe-succession couplets produces a cyclic stratigraphic record. Long-term successions are recorded in thicker stratigraphic sequences, and are of two types: 1) autogenic succession in unchanging physical environments and 2) allogenic succession in changing physical environments. Our examples of these are from the Devonian Haragan-Bois D'Arc formations of Oklahoma and the Lime Creek Formation of Iowa. This type of succession represents a temporal-spatial mosaic. The Haragan data (unchanging environments) indicate characteristic, intergrading, and ubiquitous species in the brachiopod communities. Most ubiquitous species in the pioneer community were eurytopic opportunists. The Lime Creek data allows testing of the prediction that environmental changes cause regression to an earlier succession stage. The brachiopod communities after environmental changes have more ubiquitous and intergrading eurytopic species. These represent an earlier stage in the succession.

Cleistogamy as a bet‐hedging strategy in Oxalis acetosella , a perennial herb

1998 ◽  
Vol 86 (3) ◽  
pp. 491-500 ◽  
Author(s):  
Henrik Berg ◽  
Peter Redbo‐torstensson
Keyword(s):  
Perennial Herb ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Oxalis Acetosella

scholarly journals Underestimated ecosystem carbon turnover time and sequestration under the steady state assumption: A perspective from long‐term data assimilation

2019 ◽  
Vol 25 (3) ◽  
pp. 938-953 ◽  
Author(s):  
Rong Ge ◽  
Honglin He ◽  
Xiaoli Ren ◽  
Li Zhang ◽  
Guirui Yu ◽  
...  
Keyword(s):  
Steady State ◽  
Data Assimilation ◽  
Turnover Time ◽  
Carbon Turnover ◽  
Ecosystem Carbon ◽  
Steady State Assumption ◽  
State Assumption ◽  
Term Data

scholarly journals Parental effects and the evolution of phenotypic memory

2015 ◽  
Author(s):  
Bram Kuijper ◽  
Rufus A Johnstone
Keyword(s):  
Local Environment ◽  
Parental Effects ◽  
Bet Hedging ◽  
Changing Environments ◽  
Structured Population ◽  
Different Types ◽  
Parental Phenotype ◽  
Selection For ◽  
Nongenetic Inheritance

Abstract Despite growing evidence for nongenetic inheritance, the ecological conditions that favor the evolution of heritable parental or grandparental effects remain poorly understood. Here, we systematically explore the evolution of parental effects in a patch-structured population with locally changing environments. When selection favors the production of a mix of offspring types, this mix differs according to the parental phenotype, implying that parental effects are favored over selection for bet-hedging in which the mixture of offspring phenotypes produced does not depend on the parental phenotype. Positive parental effects (generating a positive correlation between parental and offspring phenotype) are favored in relatively stable habitats and when different types of local environment are roughly equally abundant, and can give rise to long-term parental inheritance of phenotypes. By contrast, unstable habitats can favor negative parental effects (generating a negative correlation between parental and offspring phenotype), and under these circumstances even slight asymmetries in the abundance of local environmental states select for marked asymmetries in transmission fidelity.

scholarly journals Different resource allocation in a Bacillus subtilis population displaying bimodal motility

2021 ◽  
Author(s):  
Simon Syvertsson ◽  
Biwen Wang ◽  
Jojet Staal ◽  
Yongqiang Gao ◽  
Remco Kort ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bacillus Subtilis ◽  
Exponential Growth ◽  
Environmental Changes ◽  
Feedback Regulation ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Negative Feedback Regulation ◽  
Continuous Increase ◽  
Motile Cells

To cope with sudden changes in their environment, bacteria can use a bet-hedging strategy by dividing the population into cells with different properties. This so-called bimodal or bistable cellular differentiation is generally controlled by positive feedback regulation of transcriptional activators. Due to the continuous increase in cell volume, it is difficult for these activators to reach an activation threshold concentration when cells are growing exponentially. This is one reason why bimodal differentiation is primarily observed from the onset of the stationary phase when exponential growth ceases. An exception is the bimodal induction of motility in Bacillus subtilis, which occurs early during exponential growth. Several mechanisms have been put forward to explain this, including double negative-feedback regulation and the stability of the mRNA molecules involved. In this study, we used fluorescence-assisted cell sorting to compare the transcriptome of motile and non-motile cells and noted that expression of ribosomal genes is lower in motile cells. This was confirmed using an unstable GFP reporter fused to the strong ribosomal rpsD promoter. We propose that the reduction in ribosomal gene expression in motile cells is the result of a diversion of cellular resources to the synthesis of the chemotaxis and motility systems. In agreement, single-cell microscopic analysis showed that motile cells are slightly shorter than non-motile cells, an indication of slower growth. We speculate that this growth rate reduction can contribute to the bimodal induction of motility during exponential growth. IMPORTANCE To cope with sudden environmental changes, bacteria can use a bet-hedging strategy and generate different types of cells within a population, so called bimodal differentiation. For example, a Bacillus subtilis culture can contain both motile and non-motile cells. In this study we compared the gene expression between motile and non-motile cells. It appeared that motile cells express less ribosomes. To confirm this, we constructed a ribosomal promoter fusion that enabled us to measure expression of this promoter in individual cells. This reporter fusion confirmed our initial finding. The re-allocation of cellular resources from ribosome synthesis towards synthesis of the motility apparatus results in a reduction in growth. Interestingly, this growth reduction has been shown to stimulate bimodal differentiation.

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