Search for: All records

Abstract Multiple lineages in the family Poeciliidae have independently adapted to hydrogen-sulfide-rich springs. The independent colonizations of such springs mean that there are naturally replicated lineages that provide a powerful model for studying adaptation and convergent evolution. However, there are limited genomic resources for many genera and species across Poeciliidae. Here, we present six high-quality, chromosome-level, annotated genome assemblies for Poecilia and Gambusia populations, five of which are the first for the species or ecotype, and the remaining assembly improved the current reference genome contiguity by more than 100-fold. Using these new assemblies, we compare repeat content and model historical changes in effective population size. 

Abstract Genome sequencing for agriculturally important Rosaceous crops has made rapid progress both in completeness and annotation quality. Whole genome sequence and annotation give breeders, researchers, and growers information about cultivar-specific traits such as fruit quality and disease resistance, and inform strategies to enhance postharvest storage. Here we present a haplotype-phased, chromosomal-level genome of Malus domestica, ‘WA 38’, a new apple cultivar released to market in 2017 as Cosmic Crisp®. Using both short and long-read sequencing data with a k-mer-based approach, chromosomes originating from each parent were assembled and segregated. This is the first pome fruit genome fully phased into parental haplotypes in which chromosomes from each parent are identified and separated into their unique, respective haplomes. The two haplome assemblies, ‘Honeycrisp’ originated HapA and ‘Enterprise’ originated HapB, are about 650 Megabases each, and both have a BUSCO score of 98.7% complete. A total of 53,028 and 54,235 genes were annotated from HapA and HapB, respectively. Additionally, we provide genome-scale comparisons to ‘Gala’, ‘Honeycrisp’, and other relevant cultivars highlighting major differences in genome structure and gene family circumscription. This assembly and annotation was done in collaboration with the American Campus Tree Genomes project that includes ‘WA 38’ (Washington State University), ‘d’Anjou’ pear (Auburn University), and many more. To ensure transparency, reproducibility, and applicability for any genome project, our genome assembly and annotation workflow is recorded in detail and shared under a public GitLab repository. All software is containerized, offering a simple implementation of the workflow. 

Abstract Hydrogen sulfide is a toxic gas that disrupts numerous biological processes, including energy production in the mitochondria, yet fish in thePoecilia mexicanaspecies complex have independently evolved sulfide tolerance several times. Despite clear evidence for convergence at the phenotypic level in these fishes, it is unclear if the repeated evolution of hydrogen sulfide tolerance is the result of similar genomic changes. To address this gap, we used a targeted capture approach to sequence genes associated with sulfide processes and toxicity from five sulfidic and five nonsulfidic populations in the species complex. By comparing sequence variation in candidate genes to a reference set, we identified similar population structure and differentiation, suggesting that patterns of variation in most genes associated with sulfide processes and toxicity are due to demographic history and not selection. But the presence of tree discordance for a subset of genes suggests that several loci are evolving divergently between ecotypes. We identified two differentiation outlier genes that are associated with sulfide detoxification in the mitochondria that have signatures of selection in all five sulfidic populations. Further investigation into these regions identified long, shared haplotypes among sulfidic populations. Together, these results reveal that selection on standing genetic variation in putatively adaptive genes may be driving phenotypic convergence in this species complex.