Multicellularity was one of the most significant innovations in history life, but its initial evolution remains poorly understood. Using experimental evolution, we show that key steps this transition could have occurred quickly. We subjected unicellular yeast Saccharomyces cerevisiae to an environment which expected multicellularity be adaptive. observed rapid clustering genotypes display a novel multicellular life characterized by reproduction via propagules, juvenile phase, and determinate...

The contributions of adaptation, chance, and history to the evolution fitness cell size were measured in two separate experiments using bacteria. In both experiments, populations propagated identical environments achieved similar fitnesses, regardless prior or subsequent chance events. contrast, size, a trait weakly correlated with fitness, was more strongly influenced by chance.

Throughout most of the mammalian genome, genetically regulated developmental programming establishes diverse yet predictable epigenetic states across differentiated cells and tissues. At metastable epialleles (MEs), conversely, epigenotype is established stochastically in early embryo then maintained lineages, resulting dramatic systemic interindividual variation regulation. In mouse, maternal nutrition affects this process, with permanent phenotypic consequences for offspring. MEs have not...

The SUC multigene family of the single-celled yeast Saccharomyces cerevisiae is polymorphic, with genes varying both in number and activity. All encode invertase, an enzyme that secreted to digest sucrose outside cell. This communal endeavour creates potential for individual cells defect (cheat) by stealing sugar digested their neighbours without contributing themselves. We measured fitness a defector, deleted suc2 gene, relative otherwise isogenic cooperator, functional SUC2 gene....

Abstract A central feature of all adaptive radiations is morphological divergence, but the phenotypic innovations that are responsible rarely known. When selected in a spatially structured environment, populations bacterium Pseudomonas fluorescens rapidly diverge. Among divergent morphs mutant type termed “wrinkly spreader” (WS) colonizes new niche through formation self-supporting biofilms. Loci contributing to primary innovation were sought by screening WS transposon library for...

Twelve populations of the bacterium Escherichia coli were propagated for 2,000 generations in a seasonal environment, which consisted alternating periods feast and famine. The mean fitness derived genotypes increased by ∼35% relative to their common ancestor, based on competition experiments same environment. bacteria could have adapted, principle, decreasing lag prior growth upon transfer fresh medium (L), increasing maximum rate (Vm), reducing concentration resource required support at...

Abstract This study investigates the physiological manifestation of adaptive evolutionary change in 12 replicate populations Escherichia coli that were propagated for 2000 generations a glucose-limited environment. Representative genotypes from each population assayed fitness relative to their common ancestor experimental glucose environment and 11 novel single-nutrient environments. After generations, derived had diverged into at least six distinct phenotypic classes. The nutrients...

We investigate adaptive diversification in experimental Escherichia coli populations grown serial batch cultures on a mixture of glucose and acetate. All 12 lines were started from the same genetically uniform ancestral strain but became highly polymorphic for colony size after 1000 generations. Five clearly dimorphic thus serve as model an lineage split. analyzed ecological basis this dimorphism by studying bacterial growth curves. strains exhibit diauxie, that is, sequential two resources....

The effects of nonmutagenic environmental exposures can sometimes be transmitted for several generations, suggesting transgenerational inheritance induced epigenetic variation. Methyl donor supplementation female mice during pregnancy induces CpG hypermethylation at the agouti viable yellow (A(vy)) allele in A(vy)/a offspring. Epigenetic occurs A(vy); when passed through germ line, A(vy) epigenotype is not completely "reset." We therefore tested whether diet-induced alterations are inherited...

The transition to multicellularity enabled the evolution of large, complex organisms, but early steps in this remain poorly understood. Here we show that multicellular complexity, including development from a single cell, can evolve rapidly unicellular organism has never had ancestor. We subject alga Chlamydomonas reinhardtii conditions favour multicellularity, resulting life cycle which clusters reproduce via motile propagules. While single-cell genetic bottleneck during ontogeny is widely...

Abstract Complex life has arisen through a series of ‘major transitions’ in which collectives formerly autonomous individuals evolve into single, integrated organism. A key step this process is the origin higher-level evolvability, but little known about how entities originate and gain capacity to as an individual. Here we report single mutation that not only creates new level biological organization, also potentiates evolvability. Disrupting transcription factor ACE2 Saccharomyces...

Most models of speciation require gradual change and geographic or ecological isolation for new species to arise. Homoploid hybrid occurred readily between Saccharomyces cerevisiae paradoxus . Hybrids had high self-fertility (about 82%), low fertility when backcrossed either parental 7.5%), vigorous growth under different thermal environments that favored one the other species. Extensive karyotypic changes (tetrasomy) were observed in hybrids, although genic incompatibilities accounted 50%...

Organismal development and evolution are complex, multifaceted processes that depend intimately on context. They subject to environmental influences, chance appearance fixation of mutations, numerous other idiosyncrasies. Genomics is detailing the molecular signature effects these mechanisms phenotypes, but because distinct evolutionary explanations can produce a given genomic pattern, details, rather than elucidating process, typically distract from explanatory insight contribute little...

Abstract The distribution of the number pairwise differences calculated from comparisons between n haploid genomes has frequently been used as a starting point for testing hypothesis linkage equilibrium. For this purpose variance differences, VD, is test statistic to evaluate null that all loci are in problem determine critical value VD. This can be estimated either by Monte Carlo simulation or assuming VD distributed normally and calculating one-tailed 95% L, L = E(VD) + 1.645 Var(VD),...

Twelve populations of Escherichia coli were founded from a single clone and propagated for 2000 generations in identical glucose‐limited environments. During this time, the mean fitnesses evolving relative to their common ancestor improved greatly, but one another diverged only slightly. Although showed similar fitness increases, they may have done so by different underlying adaptations, or other respects random genetic drift. Therefore, we examined independently derived genotypes two...

Abstract The cause of reproductive isolation between biological species is a major issue in the field biology. Most explanations hybrid sterility require either genetic incompatibilities nascent or gross physical imbalances their chromosomes, such as rearrangements ploidy changes. An alternative possibility that genomes become incompatible at molecular level, dependent on interactions primary DNA sequences. mismatch repair system has previously been shown to contribute established yeast by...