Diepeveen, E. T. | bioRxiv Science

bioRxiv2020

Pleiotropy allows recovery of phenotypic plasticity in constant environments

Phenotypic plasticity confers a fitness advantage to an organism by tailoring phenotype to environmental circumstances. The extent to which phenotypic plasticity emerges as an adaptive response is still unknown, however it is predicted that the emergence and maintenance of phenotypic plasticity occurs only during evolution in fluctuating environments. Interestingly, experimental studies have shown that phenotypic plasticity can be preserved for several generations during evolution in a constant environment. Here, we evolve a mutant strain of Saccharomyces cerevisiae that has reduced plasticity in a constant and fluctuating environment. Subsequently we compared the adaptive response of the evolved cell, both at the phenotype and genotype level. As predicted by current theory, we find that evolution in a fluctuating environment results in a recovery of phenotypic plasticity. Surprisingly, evolution in a constant environment can lead to a similar recovery of plasticity due to a pleiotropic coupling of different traits. Thus, plasticity can emerge in both fluctuating and constant environments and its prevalence may mainly be determined by network structure. In addition, pleiotropic interactions may be an important structural component of biological networks that can facilitate the recovery of phenotypic plasticity without the requirement to continuously encounter environmental fluctuations.

evolutionary biology↗

bioRxiv2017

Patterns of conservation and diversification in the fungal polarization network

The combined actions of proteins in networks underlie all fundamental cellular functions. Deeper insights into the dynamics of network composition across species and their functional consequences are crucial to fully understand protein network evolution. Large-scale comparative studies with high phylogenetic resolution are now feasible through the recent rise in available genomic datasets of both model and non-model species. Here we focus on the polarity network, which is universally essential for cell proliferation and studied in great detail in the model organism, Saccharomyces cerevisiae. We examine 34 proteins, directly related to cell polarization, across 200 fungal strains/species to determine evolution of the composition of the network and patterns of conservation and diversification.\n\nWe observe strong protein conservation for a group of 16 core proteins: 95% of all strains/species possess at least 75% of these proteins, albeit in varying compositions. We find high levels of variation in prevalence and sequence identity in the remaining 18 proteins, resulting in distinct lineage-specific compositions of the network in the majority of strains/species. We test if the observed diversification in network composition correlates with potential underlying factors and find that lineage, lifestyle, and genetic distance co-vary with network size. Yeast, filamentous and basal unicellular fungi form distinctive groups based on these analyses, with substantial differences to their polarization network. Our study shows that evolution of the fungal polarization network is highly dynamic, even between closely related species, and that functional conservation is achieved by varying structural conservation of the fungal polarization proteins.\n\nData DepositionSequence alignments used are available upon request.

evolutionary biology↗