Macroevolutionary diversity of traits and genomes in the model yeast genus Saccharomyces.

Species is the fundamental unit to quantify biodiversity. In recent years, the model yeast Saccharomyces cerevisiae has seen an increased number of studies related to its geographical distribution, population structure, and phenotypic diversity. However, seven additional species from the same genus have been less thoroughly studied, which has limited our understanding of the macroevolutionary events leading to the diversification of this genus over the last 20 million years.

Methylothon: a Versatile Course-Based High School Research Experience in Microbiology and Bioinformatics with Pink Bacteria.

Methylothon is an inquiry-based high school learning module in microbial ecology, molecular biology, and bioinformatics that centers around pink-pigmented plant-associated methylotrophic bacteria. Here, we present an overview of the module's learning goals, describe course resources (available for public use at http://methylothon.com), and relate lessons learned from adapting Methylothon for remote learning during the pandemic in spring of 2021.

Comprehensive Phylogenomics of Methylobacterium Reveals Four Evolutionary Distinct Groups and Underappreciated Phyllosphere Diversity.

Methylobacterium is a group of methylotrophic microbes associated with soil, fresh water, and particularly the phyllosphere, the aerial part of plants that has been well studied in terms of physiology but whose evolutionary history and taxonomy are unclear. Recent work has suggested that Methylobacterium is much more diverse than thought previously, questioning its status as an ecologically and phylogenetically coherent taxonomic genus. However, taxonomic and evolutionary studies of Methylobacterium have mostly been restricted to model species, often isolated from habitats other than the phyllosphere and have yet to utilize comprehensive phylogenomic methods to examine gene trees, gene content, or synteny.

Fine-Scale Adaptations to Environmental Variation and Growth Strategies Drive Phyllosphere Diversity.

is a prevalent bacterial genus of the phyllosphere. Despite its ubiquity, little is known about the extent to which its diversity reflects neutral processes like migration and drift, versus environmental filtering of life history strategies and adaptations. In two temperate forests, we investigated how phylogenetic diversity within is structured by biogeography, seasonality, and growth strategies.

Vibrio cholerae genomic diversity within and between patients.

Cholera is a severe, water-borne diarrhoeal disease caused by toxin-producing strains of the bacterium Vibrio cholerae. Comparative genomics has revealed 'waves' of cholera transmission and evolution, in which clones are successively replaced over decades and centuries. However, the extent of V.

Evolutionary biology through the lens of budding yeast comparative genomics.

The budding yeast Saccharomyces cerevisiae is a highly advanced model system for studying genetics, cell biology and systems biology. Over the past decade, the application of high-throughput sequencing technologies to this species has contributed to this yeast also becoming an important model for evolutionary genomics. Indeed, comparative genomic analyses of laboratory, wild and domesticated yeast populations are providing unprecedented detail about many of the processes that govern evolution, including long-term processes, such as reproductive isolation and speciation, and short-term processes, such as adaptation to natural and domestication-related environments.

The Rapid Evolution of an Ohnolog Contributes to the Ecological Specialization of Incipient Yeast Species.

Identifying the molecular changes that lead to ecological specialization during speciation is one of the major goals of molecular evolution. One question that remains to be thoroughly investigated is whether ecological specialization derives strictly from adaptive changes and their associated trade-offs, or from conditionally neutral mutations that accumulate under relaxed selection. We used whole-genome sequencing, genome annotation and computational analyses to identify genes that have rapidly diverged between two incipient species of Saccharomyces paradoxus that occupy different climatic regions along a south-west to north-east gradient.

Mitochondrial Recombination and Introgression during Speciation by Hybridization.

Genome recombination is a major source of genotypic diversity and contributes to adaptation and speciation following interspecies hybridization. The contribution of recombination in these processes has been thought to be largely limited to the nuclear genome because organelles are mostly uniparentally inherited in animals and plants, which prevents recombination. Unicellular eukaryotes such as budding yeasts do, however, transmit mitochondria biparentally, suggesting that during hybridization, both parents could provide alleles that contribute to mitochondrial functions such as respiration and metabolism in hybrid populations or hybrid species.

Hybridization and adaptive evolution of diverse species for cellulosic biofuel production.

Background: Lignocellulosic biomass is a common resource across the globe, and its fermentation offers a promising option for generating renewable liquid transportation fuels. The deconstruction of lignocellulosic biomass releases sugars that can be fermented by microbes, but these processes also produce fermentation inhibitors, such as aromatic acids and aldehydes. Several research projects have investigated lignocellulosic biomass fermentation by the baker's yeast .

Speciation driven by hybridization and chromosomal plasticity in a wild yeast.

Hybridization is recognized as a powerful mechanism of speciation and a driving force in generating biodiversity. However, only few multicellular species, limited to a handful of plants and animals, have been shown to fulfil all the criteria of homoploid hybrid speciation. This lack of evidence could lead to the interpretation that speciation by hybridization has a limited role in eukaryotes, particularly in single-celled organisms.

Complex Ancestries of Lager-Brewing Hybrids Were Shaped by Standing Variation in the Wild Yeast Saccharomyces eubayanus.

Lager-style beers constitute the vast majority of the beer market, and yet, the genetic origin of the yeast strains that brew them has been shrouded in mystery and controversy. Unlike ale-style beers, which are generally brewed with Saccharomyces cerevisiae, lagers are brewed at colder temperatures with allopolyploid hybrids of Saccharomyces eubayanus x S. cerevisiae.

What Is Speciation?

Concepts and definitions of species have been debated by generations of biologists and remain controversial. Microbes pose a particular challenge because of their genetic diversity, asexual reproduction, and often promiscuous horizontal gene transfer (HGT). However, microbes also present an opportunity to study and understand speciation because of their rapid evolution, both in nature and in the lab, and small, easily sequenced genomes.

Evidence of Natural Hybridization in Brazilian Wild Lineages of Saccharomyces cerevisiae.

The natural biology of Saccharomyces cerevisiae, the best known unicellular model eukaryote, remains poorly documented and understood although recent progress has started to change this situation. Studies carried out recently in the Northern Hemisphere revealed the existence of wild populations associated with oak trees in North America, Asia, and in the Mediterranean region. However, in spite of these advances, the global distribution of natural populations of S.

The genomics of wild yeast populations sheds light on the domestication of man's best (micro) friend.

The domestication of plants, animals and microbes by humans are the longest artificial evolution experiments ever performed. The study of these long-term experiments can teach us about the genomics of adaptation through the identification of the genetic bases underlying the traits favoured by humans. In laboratory evolution, the characterization of the molecular changes that evolved specifically in some lineages is straightforward because the ancestors are readily available, for instance in the freezer.

Lachancea quebecensis sp. nov., a yeast species consistently isolated from tree bark in the Canadian province of Québec.

A thorough sampling of maple, oak, birch, and apple tree bark in North America yielded a set of isolates that represent a yeast species not yet formally described. The strains obtained were all isolated from the Canadian province of Québec. These four isolates have identical electrophoretic karyotypes, distinct from other species of the genus Lachancea, and are most closely related to the formally recognized species Lachancea thermotolerans according to the D1/D2 domain of the LSU rDNA gene and 5.

Genome-wide protein-protein interaction screening by protein-fragment complementation assay (PCA) in living cells.

Proteins are the building blocks, effectors and signal mediators of cellular processes. A protein's function, regulation and localization often depend on its interactions with other proteins. Here, we describe a protocol for the yeast protein-fragment complementation assay (PCA), a powerful method to detect direct and proximal associations between proteins in living cells.

Chromosomal variation segregates within incipient species and correlates with reproductive isolation.

Reproductive isolation is a critical step in the process of speciation. Among the most important factors driving reproductive isolation are genetic incompatibilities. Whether these incompatibilities are already present before extrinsic factors prevent gene flow between incipient species remains largely unresolved in natural systems.

Self-incompatibility in Brassicaceae: identification and characterization of SRK-like sequences linked to the S-locus in the tribe Biscutelleae.

Self-incompatibility (SI) is a genetic system that prevents self-fertilization in many Angiosperms. Although plants from the Brassicaceae family present an apparently unique SI system that is ancestral to the family, investigations at the S-locus responsible for SI have been mostly limited to two distinct lineages (Brassica and Arabidopsis-Capsella, respectively). Here, we investigated SI in a third deep-branching lineage of Brassicaceae: the tribe Biscutelleae.

Local climatic adaptation in a widespread microorganism.

Exploring the ability of organisms to locally adapt is critical for determining the outcome of rapid climate changes, yet few studies have addressed this question in microorganisms. We investigated the role of a heterogeneous climate on adaptation of North American populations of the wild yeast Saccharomyces paradoxus. We found abundant among-strain variation for fitness components across a range of temperatures, but this variation was only partially explained by climatic variation in the distribution area.

Ecological genomics of adaptation and speciation in fungi.

Fungi play a central role in both ecosystems and human societies. This is in part because they have adopted a large diversity of life history traits to conquer a wide variety of ecological niches. Here, I review recent fungal genomics studies that explored the molecular origins and the adaptive significance of this diversity.

Exploring the northern limit of the distribution of Saccharomyces cerevisiae and Saccharomyces paradoxus in North America.

We examined the northern limit of Saccharomyces cerevisiae and Saccharomyces paradoxus in northeast America. We collected 876 natural samples at 29 sites and applied enrichment methods for the isolation of mesophilic yeasts. We uncovered a large diversity of yeasts, in some cases, associated with specific substrates.

Integrative avenues for exploring the dynamics and evolution of protein interaction networks.

Over the past decade, the study of protein interaction networks (PINs) has shed light on the organizing principles of living cells. However, PINs have been mostly mapped in one single condition. We outline three of the most promising avenues of investigation in this field, namely the study of first, how PINs are rewired by mutations and environmental perturbations; secondly, how inter-species interactions affect PIN achitectures; thirdly, what mechanisms and forces drive PIN evolution.

Evidence for the robustness of protein complexes to inter-species hybridization.

Despite the tremendous efforts devoted to the identification of genetic incompatibilities underlying hybrid sterility and inviability, little is known about the effect of inter-species hybridization at the protein interactome level. Here, we develop a screening platform for the comparison of protein-protein interactions (PPIs) among closely related species and their hybrids. We examine in vivo the architecture of protein complexes in two yeast species (Saccharomyces cerevisiae and Saccharomyces kudriavzevii) that diverged 5-20 million years ago and in their F1 hybrids.

Genetic diversity and population structure in French populations of Mycosphaerella graminicola.

Mycosphaerella graminicola populations were examined in France with microsatellite markers and PCR-SSCP analysis of partial actin and β-tubulin encoding sequences. A total of 363 isolates was sampled in 2005 from 17 provinces, and genotypes from corresponding strains were characterized. Unique haplotypes comprised 84% of the population, and gene diversity was high nationwide (0.

Does frequency-dependent selection with complex dominance interactions accurately predict allelic frequencies at the self-incompatibility locus in Arabidopsis halleri?

Frequency-dependent selection is a major force determining the evolutionary dynamics of alleles at the self-incompatibility locus (S-locus) in flowering plants. We introduce a general method using numerical simulations to test several alternative models of frequency-dependent selection on S-locus data from sporophytic systems, taking into account both genetic drift and observed patterns of dominance interactions among S-locus haplotypes (S-haplotypes). Using a molecular typing method, we estimated S-haplotype frequencies in a sample of 322 adult plants and of 245 offspring obtained from seeds sampled on 22 maternal plants, collected in a single population of Arabidopsis halleri (Brassicaceae).