Mosaic of Somatic Mutations in Earth's Oldest Living Organism, Pando.

Understanding how mutations arise and spread through individuals and populations is fundamental to evolutionary biology. Most organisms have a life cycle with unicellular bottlenecks during reproduction. However, some organisms like plants, fungi, or colonial animals can grow indefinitely, changing the manner in which mutations spread throughout both the individual and the population.

Morphological Entanglement in Living Systems.

Many organisms exhibit branching morphologies that twist around each other and become entangled. Entanglement occurs when different objects interlock with each other, creating complex and often irreversible configurations. This physical phenomenon is well studied in nonliving materials, such as granular matter, polymers, and wires, where it has been shown that entanglement is highly sensitive to the geometry of the component parts.

Uncovering the hidden complexity of multicellular magnetotactic bacteria.

Multicellular magnetotactic bacteria (MMB) have a surprisingly complex multicellular lifestyle. A new study in PLOS Biology combines genomics, microscopy, and isotopic labeling to show that MMB form obligately multicellular consortia of genetically diverse cells with rudimentary division of labor.

Electric-Field Manipulation of Magnetic Chirality in a Homo-Ferro-Rotational Helimagnet.

Ferro-rotational (FR) materials, renowned for their distinctive material functionalities, present challenges in the growth of homo-FR crystals (i.e., single FR domain).

Metabolically-driven flows enable exponential growth in macroscopic multicellular yeast.

The ecological and evolutionary success of multicellular lineages is due in no small part to their increased size relative to unicellular ancestors. However, large size also poses biophysical challenges, especially regarding the transport of nutrients to all cells; these constraints are typically overcome through multicellular innovations (e.g.

Whole-genome duplication in the Multicellularity Long Term Evolution Experiment.

Whole-genome duplication (WGD) is widespread across eukaryotes and can promote adaptive evolution. However, given the instability of newly-formed polyploid genomes, understanding how WGDs arise in a population, persist, and underpin adaptations remains a challenge. Using our ongoing Multicellularity Long Term Evolution Experiment (MuLTEE), we show that diploid snowflake yeast () under selection for larger multicellular size rapidly undergo spontaneous WGD.

Macroalgal deep genomics illuminate multiple paths to aquatic, photosynthetic multicellularity.

Macroalgae are multicellular, aquatic autotrophs that play vital roles in global climate maintenance and have diverse applications in biotechnology and eco-engineering, which are directly linked to their multicellularity phenotypes. However, their genomic diversity and the evolutionary mechanisms underlying multicellularity in these organisms remain uncharacterized. In this study, we sequenced 110 macroalgal genomes from diverse climates and phyla, and identified key genomic features that distinguish them from their microalgal relatives.

Emergence and maintenance of stable coexistence during a long-term multicellular evolution experiment.

The evolution of multicellular life spurred evolutionary radiations, fundamentally changing many of Earth's ecosystems. Yet little is known about how early steps in the evolution of multicellularity affect eco-evolutionary dynamics. Through long-term experimental evolution, we observed niche partitioning and the adaptive divergence of two specialized lineages from a single multicellular ancestor.

Proteostatic tuning underpins the evolution of novel multicellular traits.

The evolution of multicellularity paved the way for the origin of complex life on Earth, but little is known about the mechanistic basis of early multicellular evolution. Here, we examine the molecular basis of multicellular adaptation in the multicellularity long-term evolution experiment (MuLTEE). We demonstrate that cellular elongation, a key adaptation underpinning increased biophysical toughness and organismal size, is convergently driven by down-regulation of the chaperone Hsp90.

Constitutive expression of the Type VI Secretion System carries no measurable fitness cost in .

The Type VI Secretion System (T6SS) is a widespread and highly effective mechanism of microbial warfare; it confers the ability to efficiently kill susceptible cells within close proximity. Due to its large physical size, complexity, and ballistic basis for intoxication, it has widely been assumed to incur significant growth costs in the absence of improved competitive outcomes. In this study, we precisely examine the fitness costs of constitutive T6SS firing in the bacterium .

A nonadaptive explanation for macroevolutionary patterns in the evolution of complex multicellularity.

"Complex multicellularity," conventionally defined as large organisms with many specialized cell types, has evolved five times independently in eukaryotes, but never within prokaryotes. A number of hypotheses have been proposed to explain this phenomenon, most of which posit that eukaryotes evolved key traits (e.g.

Transforming yeast into a facultative photoheterotroph via expression of vacuolar rhodopsin.

Phototrophic metabolism, the capture of light for energy, was a pivotal biological innovation that greatly increased the total energy available to the biosphere. Chlorophyll-based photosynthesis is the most familiar phototrophic metabolism, but retinal-based microbial rhodopsins transduce nearly as much light energy as chlorophyll does, via a simpler mechanism, and are found in far more taxonomic groups. Although this system has apparently spread widely via horizontal gene transfer, little is known about how rhodopsin genes (with phylogenetic origins within prokaryotes) are horizontally acquired by eukaryotic cells with complex internal membrane architectures or the conditions under which they provide a fitness advantage.

Examining the role of oxygen-binding proteins on the early evolution of multicellularity.

Oxygen availability is a key factor in the evolution of multicellularity, as larger and more sophisticated organisms often require mechanisms allowing efficient oxygen delivery to their tissues. One such mechanism is the presence of oxygen-binding proteins, such as globins and hemerythrins, which arose in the ancestor of bilaterian animals. Despite their importance, the precise mechanisms by which oxygen-binding proteins influenced the early stages of multicellular evolution under varying environmental oxygen levels are not yet clear.

Trade-offs constrain adaptive pathways to the type VI secretion system survival.

The Type VI Secretion System (T6SS) is a nano-harpoon used by many bacteria to inject toxins into neighboring cells. While much is understood about mechanisms of T6SS-mediated toxicity, less is known about the ways that competitors can defend themselves against this attack, especially in the absence of their own T6SS. Here we subjected eight replicate populations of to T6SS attack by .

A non-adaptive explanation for macroevolutionary patterns in the evolution of complex multicellularity.

"Complex multicellularity", conventionally defined as large organisms with many specialized cell types, has evolved five times independently in eukaryotes, but never within prokaryotes. A number hypotheses have been proposed to explain this phenomenon, most of which posit that eukaryotes evolved key traits (., dynamic cytoskeletons, alternative mechanisms of gene regulation, or subcellular compartments) which were a necessary prerequisite for the evolution of complex multicellularity.

Evolutionary consequences of nascent multicellular life cycles.

A key step in the evolutionary transition to multicellularity is the origin of multicellular groups as biological individuals capable of adaptation. Comparative work, supported by theory, suggests clonal development should facilitate this transition, although this hypothesis has never been tested in a single model system. We evolved 20 replicate populations of otherwise isogenic clonally reproducing 'snowflake' yeast (Δ) and aggregative 'floc' yeast (pp) with daily selection for rapid growth in liquid media, which favors faster cell division, followed by selection for rapid sedimentation, which favors larger multicellular groups.

Spontaneous Emergence of Multicellular Heritability.

The major transitions in evolution include events and processes that result in the emergence of new levels of biological individuality. For collectives to undergo Darwinian evolution, their traits must be heritable, but the emergence of higher-level heritability is poorly understood and has long been considered a stumbling block for nascent evolutionary transitions. Using analytical models, synthetic biology, and biologically-informed simulations, we explored the emergence of trait heritability during the evolution of multicellularity.

The science of storytelling: the David Attenborough style of scientific presentation.

Many scientists approach speaking as they do writing a paper: an opportunity to present their data. But data without proper context is difficult to absorb. In this article, I describe a philosophy and set of heuristics for giving an engaging, narratively driven talk, inspired by the legendary documentaries of Sir David Attenborough.

Proteostatic tuning underpins the evolution of novel multicellular traits.

The evolution of multicellularity paved the way for the origin of complex life on Earth, but little is known about the mechanistic basis of early multicellular evolution. Here, we examine the molecular basis of multicellular adaptation in the Multicellularity Long Term Evolution Experiment (MuLTEE). We demonstrate that cellular elongation, a key adaptation underpinning increased biophysical toughness and organismal size, is convergently driven by downregulation of the chaperone Hsp90.

De novo evolution of macroscopic multicellularity.

While early multicellular lineages necessarily started out as relatively simple groups of cells, little is known about how they became Darwinian entities capable of sustained multicellular evolution. Here we investigate this with a multicellularity long-term evolution experiment, selecting for larger group size in the snowflake yeast (Saccharomyces cerevisiae) model system. Given the historical importance of oxygen limitation, our ongoing experiment consists of three metabolic treatments-anaerobic, obligately aerobic and mixotrophic yeast.

Evolution: Understanding the origins of facultative multicellular life cycles.

Multicellular organisms exhibit a fascinating diversity of life cycles, but little is known about the factors governing life-cycle evolution. New studies of wild yeast and cyanobacteria provide insight into how and why facultative multicellular life cycles arise.

Emergence and maintenance of stable coexistence during a long-term multicellular evolution experiment.

The evolution of multicellular life spurred evolutionary radiations, fundamentally changing many of Earth’s ecosystems. Yet little is known about how early steps in the evolution of multicellularity transform eco-evolutionary dynamics, e.g.

Illuminating a new path to multicellularity.

A new species of multicellular bacteria broadens our understanding of prokaryotic multicellularity and provides insight into how multicellular organisms arise.

A semi-supervised deep-learning approach for automatic crystal structure classification.

The structural solution problem can be a daunting and time-consuming task. Especially in the presence of impurity phases, current methods, such as indexing, become more unstable. In this work, the novel approach of semi-supervised learning is applied towards the problem of identifying the Bravais lattice and the space group of inorganic crystals.

Varied solutions to multicellularity: The biophysical and evolutionary consequences of diverse intercellular bonds.

The diversity of multicellular organisms is, in large part, due to the fact that multicellularity has independently evolved many times. Nonetheless, multicellular organisms all share a universal biophysical trait: cells are attached to each other. All mechanisms of cellular attachment belong to one of two broad classes; intercellular bonds are either reformable or they are not.