Project description:Selfing plant lineages are surprisingly widespread and successful in a broad range of environments, despite showing reduced genetic diversity, which is predicted to reduce their long-term evolutionary potential. However, appropriate short-term plastic responses to new environmental conditions might not require high levels of standing genetic variation. In this study, we tested whether mating system variation among populations, and associated changes in genetic variability, affected short-term responses to environmental challenges. We compared relative fitness and metabolome profiles of naturally outbreeding (genetically diverse) and inbreeding (genetically depauperate) populations of a perennial plant, <i>Arabidopsis lyrata</i>, under constant growth chamber conditions and an outdoor common garden environment outside its native range. We found no effect of inbreeding on survival, flowering phenology or short-term physiological responses. Specifically, naturally occurring inbreeding had no significant effects on the plasticity of metabolome profiles, using either multivariate approaches or analysis of variation in individual metabolites, with inbreeding populations showing similar physiological responses to outbreeding populations over time in both growing environments. We conclude that low genetic diversity in naturally inbred populations may not always compromise fitness or short-term physiological capacity to respond to environmental change, which could help to explain the global success of selfing mating strategies.
Project description:Two thirds of Earth’s species have undergone population declines, leaving many vulnerable to genomic erosion and inbreeding depression. Genetic rescue can boost fitness of small populations, but perceived risks of outbreeding depression can limit its use. We quantified these trade-offs in hundreds of endangered Pacific pocket mice (Perognathus longimembris pacificus), combining whole genome sequences with fitness data. The impacts of genomic erosion in remnant populations were reversed in an admixed breeding program, suggesting potential benefits of genetic rescue. However, differences in chromosome numbers increase the risk of genetic incompatibilities. Fitness analyses suggested that although admixed karyotypes may have reduced fertility, non-admixed mice with low heterozygosity and high genetic load had even lower fitness, pointing to a greater risk of extinction if populations remain isolated.
Project description:The black-footed ferret (Mustela nigripes) is a star example of the efforts of conservation programs in bringing endangered species back from the brink of extinction. As one of the world’s most endangered mammals, the vast majority of black-footed ferrets living in the wild today are the offspring of a founding captive population. The success of this ongoing breeding program, however, is threatened by inbreeding depression and the observed decline in pregnancy rates since its founding. As the wild and modern captive populations share a genetic history, the greatest difference between the two groups is the captive environment of the breeding program. In this study, we used RNA sequencing and proteomics for the first time in black-footed ferrets to explore whether the diet of wild ferrets versus captive diet variants could explain the differences in fertility and sperm characteristics observed between each population. We find that changes in both the transcriptional and proteomic profile of black-footed ferret ejaculate are strongly associated with differences in fertility, especially in pathways associated with innate immunity and metabolism; that transcriptional changes are further exacerbated by diet. Overall, our results support the hypothesis of ongoing environmental-dependent inbreeding depression in the black-footed ferret, with a need to re-evaluate dietary and environmental parameters of the conservation program; and also illustrates the value of multi-level genomics for conservation management programs.
2023-09-20 | PXD044152 | Pride
Project description:Diet of a threatened rattlesnake (eastern massasauga) revealed by DNA metabarcoding
| PRJNA947179 | ENA
Project description:Historical Contingency Limits Adaptive Diversification in a Spatially Structured Environment
Project description:Biofilms undergo a life cycle where cells attach to a surface, grow and produce a structured community before dispersing to seed biofilms in new environments. Progression through this life cycle requires controlled temporal gene expression to maximise fitness at each stage. Previous studies have focused on the essential genome for the formation of a mature biofilm, but here we present an insight into the genes involved at different stages of biofilm formation. We used TraDIS-Xpress (a massively parallel transposon mutagenesis using transposon-located promoters to assay expression of all genes in the genome) to determine how gene essentiality and expression affects the fitness of E. coli growing as a biofilm on glass beads after 12, 24 and 48 hours. An E. coli transposon mutant library of approximately 800,000 unique mutants was grown on glass beads, and a planktonic sample was taken alongside this at each time point to compare gene essentiality and expression at each time point.
Project description:Aneuploidy is a hallmark of tumor cells, and yet the precise relationship between aneuploidy and a cell’s proliferative ability, or cellular fitness, has remained elusive. In this study, we have combined a detailed analysis of aneuploid clones isolated from laboratory-evolved populations of Saccharomyces cerevisiae with a systematic, genome-wide screen for the fitness effects of telomeric amplifications to address the relationship between aneuploidy and cellular fitness. We found that aneuploid clones rise to high population frequencies in nutrient-limited evolution experiments and show increased fitness relative to wild type. Direct competition experiments confirmed that three out of four aneuploid events isolated from evolved populations were themselves sufficient to improve fitness. To expand the scope beyond this small number of exemplars, we created a genome-wide collection of >1,800 diploid yeast strains, each containing a different telomeric amplicon (Tamp), ranging in size from 0.4 to 1,000 kb. Using pooled competition experiments in nutrient-limited chemostats followed by high-throughput sequencing of strain-identifying barcodes, we determined the fitness effects of these >1,800 Tamps under three different conditions. Our data revealed that the fitness landscape explored by telomeric amplifications is much broader than that explored by single-gene amplifications. As also observed in the evolved clones, we found the fitness effects of most Tamps to be condition specific, with a minority showing common effects in all three conditions. By integrating our data with previous work that examined the fitness effects of single-gene amplifications genome-wide, we found that a small number of genes within each Tamp are centrally responsible for each Tamp’s fitness effects. Our genome-wide Tamp screen confirmed that telomeric amplifications identified in laboratory-evolved populations generally increased fitness. Our results show that Tamps are mutations that produce large, typically condition-dependent changes in fitness that are important drivers of increased fitness in asexually evolving populations.
Project description:Clonal communities of single celled organisms, such as bacterial or fungal colonies and biofilms, are spatially structured, with subdomains of cells experiencing differing environmental conditions. In the development of such communities, cell specialization is not only important to respond and adapt to the local environment but has the potential to increase the fitness of the clonal community through division of labor. Here, we examine colony development in a yeast strain (F13) that produces colonies with a highly structured “ruffled” phenotype in the colony periphery and an unstructured “smooth” phenotype in the colony center. We demonstrate that in the F13 genetic background deletions of transcription factors can either increase (dig1 deletion, sfl1 deletion) or decrease (tec1deletion) the degree of colony structure. We identify genes responding additively and non-additively to the genotype and spatiotemporal factors and cluster these genes into a number of different expression patterns, including patterns that correlate closely with the degree of colony structure in each sample and include genes with known roles in the development of colony structure. Individual deletion of 26 genes sampled from different clusters identified 5 with strong effects on colony morphology (BUD8, CIS3, FLO11, MSB2 and SFG1), all of which eliminated or greatly reduced the structure of the F13 outer region.