Biology subjects

Hodgins, K.

Publications and source records attributed to Hodgins, K..

5 recordsLinked to original sources

bioRxiv2026

Historical genomes reveal scale-dependent predictability of climate adaptation

Predicting evolution remains a central challenge in biology. Contemporary spatial patterns are increasingly used as space-for-time proxies to forecast evolutionary responses to environmental change, yet the reliability of such predictions--and whether it varies among biological scales--remains unclear. Using historical and contemporary genomes of the invasive weed Ambrosia artemisiifolia--spanning the species' native range, invasions on two continents and nearly two centuries--we show that genomically predicted flowering-time clines remained stable in the native range while introduced populations re-evolved them. Haploblocks--likely structural variants--were likewise temporally stable in the native range, and two showed striking parallel evolution across all three ranges. Climate-associated SNPs with the strongest contemporary clines showed the greatest temporal change, with limited and variable parallelism among introduced ranges. Together, these results suggest adaptive evolution is partly predictable even when individual genomic trajectories remain flexible and contingent, with predictability emerging most clearly at the level of polygenic traits and large structural variants.

evolutionary biology↗

bioRxiv2024

A phased chromosome-level genome of the annelid tubeworm Galeolaria caespitosa

Haplotype-resolved (phased) genome assemblies are emerging as important assets for genomic studies of species with high heterozygosity, but remain lacking for key animal lineages. Here, we use PacBio HiFi and Omni-C technologies to assemble the first phased, annotated, chromosome-level genome for any annelid: the reef-building tubeworm Galeolaria caespitosa (Serpulidae). The assembly is 803.5 Mbp long (scaffold N50 = 76.5 Mbp) for haplotype 1 and 789.3 Mbp long (scaffold N50 = 75.4 Mbp) for haplotype 2, which are arranged into 11 pairs of chromosomes showing no sign of sex chromosomes. This compares with cytological analyses reporting 12-13 pairs in Galeolarias closest relatives, including species that are protandrous hermaphrodites. We combined long-read and short-read transcriptome sequencing to annotate both haplotypes, resulting in 43,191 predicted proteins for haplotype 1, 39,675 proteins for haplotype two, and 55.5% of proteins with at least one functional annotation. We also assembled a mitochondrial genome 23 Kbp long, annotating all genes typically found in mitochondrial DNA apart from those coding the 16S ribosomal subunit and the protein atp8 -- a short, fast-evolving mitochondrial gene missing in other metazoans. Comparing Galeolarias genome to those of three other annelids reveals limited collinearity despite 32.2% of shared orthologous gene clusters (4,248 of 13,174 clusters counted in Galeolaria), suggesting extensive chromosomal rearrangements among lineages. New high-quality annelid genomes may help resolve the genetic and evolutionary basis of this diversity.

genomics↗

bioRxiv2023

Haplotype-resolved, chromosome-level assembly of white clover (Trifolium repens L., Fabaceae)

BackgroundWhite clover (Trifolium repens L.; Fabaceae) is an important forage and cover crop in agricultural pastures around the world, and is increasingly used in evolutionary ecology and genetics to understand the genetic basis of adaptation. Historically, improvements in white clover breeding practices and assessments of genetic variation in nature have been hampered by a lack of high-quality genomic resources for this species, owing in part to its high heterozygosity and allotetraploid hybrid origin. FindingsHere, we use PacBio HiFi and chromosome conformation capture (Omni-C) technologies to generate a chromosome-level, haplotype-resolved genome assembly for white clover totaling 998 Mbp (scaffold N50 = 59.3 Mbp) and 1 Gbp (scaffold N50 = 58.6 Mbp) for haplotypes 1 and 2, respectively, with each haplotype arranged into 16 chromosomes (8 per subgenome). We additionally provide a functionally annotated haploid mapping assembly (968 Mbp, scaffold N50 = 59.9 Mbp), which drastically improves on the existing reference assembly in both contiguity and assembly accuracy. We annotated 78,174 protein-coding genes, resulting in protein BUSCO completeness scores of 99.6% and 99.3% against the embryophyta_odb10 and fabales_odb10 lineage datasets, respectively. ConclusionsWe provide two white clover genome assemblies as part of this project: (1) a haplotype-resolved, chromosome-level assembly, and (2) a functionally annotated haploid mapping assembly. These assemblies place white clover among the best sequenced legumes to date, and one of the best assemblies for a plant of recent polyploid origins. This work promises to facilitate ongoing and future work in agricultural and evolutionary genetics in this agronomically and ecologically important species.

genomics↗

bioRxiv2021

Pleiotropy drives repeatability in the genetic basis of adaptation

Observations of genetically repeated evolution (repeatability) in complex organisms are incongruent with the Fisher-Orr model, which implies that repeated use of the same gene should be rare when mutations are pleiotropic (i.e., affect multiple traits). When spatially divergent selection occurs in the presence of migration, mutations of large effect are more strongly favoured, and hence repeatability is more likely, but it is unclear whether this observation is limited by pleiotropy. Here, we explore this question using individual-based simulations of a two-patch model incorporating multiple quantitative traits governed by mutations with pleiotropic effects. We explore the relationship between fitness trade-offs and repeatability by varying the alignment between mutation effect and spatial variation in trait optima. While repeatability decreases with increasing trait dimensionality, trade-offs in mutation effects on traits do not strongly limit the contribution of a locus of large effect to repeated adaptation, particularly under increased migration. These results suggest that repeatability will be more pronounced for local rather than global adaptation. Whereas pleiotropy limits repeatability in a single-population model, when there is local adaptation with gene flow, repeatability can occur if some loci are able to produce alleles of large effect, even when there are pleiotropic trade-offs. Article summaryClassical evolutionary theory predicts that genetically repeated evolution should be vanishingly rare in organisms where mutations affect multiple traits. In this article, we use simulations to study such pleiotropic mutations, and explore their effects on local adaptation in two patches under divergent selection. We find that migration between patches increases the likelihood of repeated evolution, even when there are fitness trade-offs imposed by pleiotropy.

genetics↗

bioRxiv2017

Modular environmental pleiotropy of genes involved in local adaptation to climate despite physical linkage

BackgroundPhysical linkage among genes shaped by different sources of selection is a fundamental aspect of genetic architecture. Theory predicts that evolution in complex environments selects for modular genetic architectures and high recombination rates among loci shaped by different sources of selection. However, limited data exist to test these predictions because the field lacks consensus for how to control for intercorrelated environmental variables. Here, we introduce a co-association network analysis, which clusters loci based on differing environmental associations, and use it to study the genetic architecture of local adaptation to climate in lodgepole pine (Pinus contorta).\n\nResultsWe identified many modules of genes associated with distinct environments (aridity, freezing, geography), and discovered low recombination rates among some candidate genes in different modules. We observed limited evidence for environmental pleiotropic effects on distinct aspects of climate. We also found limited correspondence between the modularity of co-association networks and gene regulatory networks. We compared co-association networks to associations with principal components, and found the latter can lead to misinterpretation. Finally, we used simulations to illustrate the benefits and caveats of co-association networks.\n\nConclusionsCo-association networks provided a useful framework for studying modularity. Our results supported the prediction that evolution to complex environments selects for modular genetic architectures, but some of our results went against the prediction that selection would increase recombination among loci experiencing different sources of selection. These results give new insight into evolutionary debates about the extent of modularity and pleiotropy in the evolution of genetic architectures.

evolutionary biology↗