Impact of extrinsic incubation temperature on natural selection during Zika virus infection of Aedes aegypti and Aedes albopictus

Arthropod-borne viruses (arboviruses) require replication across a wide range of temperatures to perpetuate. While vertebrate hosts tend to maintain temperatures of approximately 37°C—40°C, arthropods are subject to ambient temperatures which can have a daily fluctuation of > 10°C. Temperatures impact vector competence, extrinsic incubation period, and mosquito survival unimodally, with optimal conditions occurring at some intermediate temperature. In addition, the mean and range of daily temperature fluctuations influence arbovirus perpetuation and vector competence. The impact of temperature on arbovirus genetic diversity during systemic mosquito infection, however, is poorly understood. Therefore, we determined how constant extrinsic incubation temperatures of 25°C, 28°C, 32°C, and 35°C control Zika virus (ZIKV) vector competence and population dynamics within Aedes aegypti and Aedes albopictus mosquitoes. We also examined fluctuating temperatures which better mimic field conditions in the tropics. We found that vector competence varied in a unimodal manner for constant temperatures peaking between 28°C and 32°C for both Aedes species. Transmission peaked at 10 days post-infection for Aedes aegypti and 14 days for Aedes albopictus. Conversely, fluctuating temperature decreased vector competence. Using RNA-seq to characterize ZIKV population structure, we identified that temperature alters the selective environment in unexpected ways. During mosquito infection, constant temperatures more often elicited positive selection whereas fluctuating temperatures led to strong purifying selection in both Aedes species. These findings demonstrate that temperature has multiple impacts on ZIKV biology, including major effects on the selective environment within mosquitoes.

Evidence for the dependence of the SARS-Cov-2 Delta high diffusivity on the associated N:G215C nucleocapsid mutation

The continuous evolution of the SARS-CoV-2 virus genome and the consequent substitutions observed in the amino acid sequences, can induce significant changes in parameters such as diffusivity and pathogenicity, and causes constant concern regarding the efficacy of vaccines against the new variants in circulation. In recent months there has been an increase in the number of infections first in India, and more recently in the United Kingdom. The genome sequencing of the samples showed that this increase coincided with the emergence of a new variant, B.1.617.2, also known as VOC Delta. This variant is rapidly becoming dominant in several countries, causing increasing concern for its extreme diffusivity and its ability to often overcome the vaccines. The high diffusivity of this variant is normally ascribed to the Spike protein mutations. However, we will show here that it is rather due to the nucleocapsid substitution N:G215C. This is made clear by comparing, in the genomic sequences available on the GISAID database, the relative increase of the Delta variant with and without the associated N:G215C substitution. Once the extreme diffusivity of the Delta variant with associated nucleocapsid aminoacidic substitution is evidenced, we tentatively explain it as possibly due to the adaptive effect of the highly selective environment in Countries with high levels of vaccination.

Evolution of Plant Niche Construction Traits in Biogeomorphic Landscapes

By virtue of niche construction traits, plants play a significant role in shaping landscapes. The resultant outcome is a change in the selective environment, which influences the evolution of these same plants. So far almost all biogeomorphic models have assumed that niche construction traits are invariant in time. On the other hand, niche construction studies have assumed that independent abiotic changes are either nonexistent or are simply linear. Here, I considered the concomitant evolution of plant niche construction traits during landscape development. I constructed a geo-evolutionary model that couples a population genetic module with a landscape development module. Allowing plants to evolve always results in landforms different from those that appear when evolution is not accounted for. The topographic difference between cases with and without evolution ranges from a small difference in the steady-state topography, to drastic differences in landforms. The amount of difference is contingent upon forms of landscape development and the strength of geo-evolutionary coupling. Allowing the landscape to develop while evolution occurs changes evolutionary trajectories for niche construction traits. The landscape can even develop spatial structures that suppress selection. Model results clearly support the need to integrate niche construction theory and biogeomorphology to better understand both.

On the Explicit Function of Life within a Physical Universe

To describe the meaning of functionality in a universe before life evolved, existing etiological and systemic accounts of function are evaluated. Since the theory of function is only applicable in context with living beings and artifacts used by living beings and therefore cannot predict how a prebiotic form of functionality could evolve, a maintenance account for functionality is proposed. This account ascribes functionality to a structurally disposed property that increases the probability of maintenance or recurrence of the property in the surrounding selective environment. With the help of the maintenance account and a concept of physical information comprising kinetic and structural types of information, possible evolutionary processes preceding the evolution of life are explored. As important mechanisms in abiotic and prebiotic evolution, linear and non-linear mixing processes, as well as dynamics of solitary waves, are identified. Before the question of the meaning of life in prebiotic environments is renewed and an educated guess based on the elaborated arguments is made on the progress of evolution under the influencing impression of the living state, the evolution of functionality in different selective contexts is analyzed.

Experimental evolution of Bacillus subtilis on Arabidopsis thaliana roots reveals fast adaptation and improved root colonization in the presence of soil microbes

The soil ubiquitous Bacillus subtilis is known to promote plant growth and protect plants against disease. These characteristics make B. subtilis highly relevant in an agricultural perspective, fueling the interest in studying B. subtilis-plant interactions. Here, we employ an experimental evolution approach to explore adaptation of B. subtilis to Arabidopsis thaliana roots. B. subtilis rapidly adapts to the plant root environment, as evidenced by improved root colonizers observed already after 12 consecutive transfers between seedlings in a hydroponic setup. Further phenotypic characterization of evolved isolates from transfer 30 revealed that increased root colonization was associated with robust biofilm formation in response to the plant polysaccharide xylan. Additionally, several evolved isolates across independent populations were impaired in motility, a redundant trait in the selective environment. Interestingly, two evolved isolates outcompeted the ancestor during competition on the root but suffered a fitness disadvantage in non-selective environment, demonstrating an evolutionary cost of adaptation to the plant root. Finally, increased root colonization by a selected evolved isolate was also demonstrated in the presence of resident soil microbes. Our findings provide novel insights into how a well-known PGPR rapidly adapts to an ecologically relevant environment and reveal evolutionary consequences that are fundamental to consider when evolving strains for biocontrol purposes.

First steps in assessing microbial involvement in the geochemical evolution of uranium mine tailings : evaluation of iron reduction potential, biofilm formation and community heterogeneity

The high pH (~10) and elevated concentration of metals and oxyanions such as As, Fe, Ni, Mo and Se in the Deilmann tailings management facility (DTMF) presents a highly selective environment for microorganisms. The objective of this study was to assess the potential for metal and ion solubilization by the indigenous mixed microbial community in both optimum (high carbon) and

First steps in assessing microbial involvement in the geochemical evolution of uranium mine tailings : evaluation of iron reduction potential, biofilm formation and community heterogeneity

The high pH (~10) and elevated concentration of metals and oxyanions such as As, Fe, Ni, Mo and Se in the Deilmann tailings management facility (DTMF) presents a highly selective environment for microorganisms. The objective of this study was to assess the potential for metal and ion solubilization by the indigenous mixed microbial community in both optimum (high carbon) and

The evolution of social learning as phenotypic cue integration

Most analyses of the origins of cultural evolution focus on when and where social learning prevails over individual learning, overlooking the fact that there are other developmental inputs that influence phenotypic fit to the selective environment. This raises the question of how the presence of other cue ‘channels’ affects the scope for social learning. Here, we present a model that considers the simultaneous evolution of (i) multiple forms of social learning (involving vertical or horizontal learning based on either prestige or conformity biases) within the broader context of other evolving inputs on phenotype determination, including (ii) heritable epigenetic factors, (iii) individual learning, (iv) environmental and cascading maternal effects, (v) conservative bet-hedging, and (vi) genetic cues. In fluctuating environments that are autocorrelated (and hence predictable), we find that social learning from members of the same generation (horizontal social learning) explains the large majority of phenotypic variation, whereas other cues are much less important. Moreover, social learning based on prestige biases typically prevails in positively autocorrelated environments, whereas conformity biases prevail in negatively autocorrelated environments. Only when environments are unpredictable or horizontal social learning is characterized by an intrinsically low information content, other cues such as conservative bet-hedging or vertical prestige biases prevail. This article is part of the theme issue ‘Foundations of cultural evolution’.

Hidden paths to endless forms most wonderful: parasite-blind diversification of host quality

Evolutionary diversification can occur in allopatry or sympatry, can be driven by selection or unselected, and can be phenotypically manifested immediately or remain latent until manifested in a newly encountered environment. Diversification of host–parasite interactions is frequently studied in the context of intrinsically selective coevolution, but the potential for host–parasite interaction phenotypes to diversify latently during parasite-blind host evolution is rarely considered. Here, we use a social bacterium experimentally adapted to several environments in the absence of phage to analyse allopatric diversification of host quality—the degree to which a host population supports a viral epidemic. Phage-blind evolution reduced host quality overall, with some bacteria becoming completely resistant to growth suppression by phage. Selective-environment differences generated only mild divergence in host quality. However, selective environments nonetheless played a major role in shaping evolution by determining the degree of stochastic diversification among replicate populations within treatments. Ancestral motility genotype was also found to strongly shape patterns of latent host-quality evolution and diversification. These outcomes show that (i) adaptive landscapes can differ in how they constrain stochastic diversification of a latent phenotype and (ii) major effects of selection on biological diversification can be missed by focusing on trait means. Collectively, our findings suggest that latent-phenotype evolution should inform host–parasite evolution theory and that diversification should be conceived broadly to include latent phenotypes.