Biology subjects

Bieker, V. C.

Publications and source records attributed to Bieker, V. C..

4 recordsLinked to original sources

bioRxiv2022

Multiple paths towards repeated phenotypic evolution in the spiny-leg adaptive radiation (Tetragnatha; Hawaii)

The repeated evolution of phenotypes is ubiquitous in nature and offers some of the clearest evidence of the role of natural selection in evolution. The genomic basis of repeated phenotypic evolution is often complex and can arise from a combination of gene flow, shared ancestral polymorphism and de novo mutation. Here, we investigate the genomic basis of repeated ecomorph evolution in the adaptive radiation of the Hawaiian spiny-leg Tetragnatha. This radiation comprises four ecomorphs that are microhabitat-specialists, and differ in body pigmentation and size (Green, Large Brown, Maroon, and Small Brown). Using 76 newly generated low-coverage, whole-genome resequencing samples, coupled with population genomic and phylogenomic tools, we studied the evolutionary history of the radiation to understand the evolution of the spiny-leg lineage and the genetic underpinnings of ecomorph evolution. Congruent with previous works, we find that each ecomorph has evolved twice, with the exception of the Small Brown ecomorph, which has evolved three times. The evolution of the Maroon and the Small Brown ecomorphs likely involved ancestral hybridization events, whereas the Green and the Large Brown ecomorphs likely evolved because of either standing genetic variation or de novo mutation. Pairwise comparisons of ecomorphs based on the fixation index (FST) show that divergent genomic regions include genes with functions associated with pigmentation (melanization), learning, neuronal and synapse activity, and circadian rhythms. These results show that the repeated evolution of ecomorphs in the Hawaiian spiny-leg Tetragnatha is linked to multiple genomic regions and suggests a previously unknown role of learning and circadian rhythms in ecomorph.

evolutionary biology↗

bioRxiv2022

Contrasting genomic consequences of anthropogenic reintroduction and natural recolonisation in high-arctic wild reindeer

Anthropogenic reintroduction can supplement natural recolonisation in reestablishing a species distribution and abundance. However, both reintroductions and recolonisations can give rise to population bottlenecks that reduce genetic diversity and increase inbreeding, potentially causing accumulation of genetic load and reduced fitness. Most current populations of the endemic high-arctic Svalbard reindeer (Rangifer tarandus platyrhynchus) originate from recent reintroductions or recolonisations following regional extirpations due to past overharvesting. We investigated and compared the genomic consequences of these two paths to reestablishment using whole-genome shotgun sequencing of 100 Svalbard reindeer across their range. We found little admixture between reintroduced and natural populations. Two reintroduced populations, each founded by 12 individuals around four decades (i.e. 8 reindeer generations) ago, formed two distinct genetic clusters. Compared to the source population, these populations showed only small decreases in genome-wide heterozygosity and increases in inbreeding and lengths of runs of homozygosity. In contrast, the two naturally recolonised populations without admixture possessed much lower heterozygosity, higher inbreeding, and longer runs of homozygosity, possibly caused by serial population bottlenecks and/or fewer or more genetically related founders than in the reintroduction events. Naturally recolonised populations can thus be more vulnerable to the accumulation of genetic load than reintroduced populations. This suggests that in some organisms even small-scale reintroduction programs based on genetically diverse source populations can be more effective than natural recolonisation in establishing genetically diverse populations. These findings warrant particular attention in the conservation and management of populations and species threatened by habitat fragmentation and loss.

genomics↗

bioRxiv2022

Large haploblocks underlie rapid adaptation in an invasive weed

Adaptation is the central feature and leading explanation for the evolutionary diversification of life. Adaptation is also notoriously difficult to study in nature, owing to its complexity and logistically prohibitive timescale. We leverage extensive contemporary and historical collections of Ambrosia artemisiifolia--an aggressively invasive weed and primary cause of pollen-induced hayfever--to track the phenotypic and genetic causes of recent local adaptation across its native and invasive ranges in North America and Europe, respectively. Large haploblocks-- indicative of chromosomal inversions--contain a disproportionate share (26%) of genomic regions conferring parallel adaptation to local climates between ranges, are associated with rapidly adapting traits, and exhibit dramatic frequency shifts over space and time. These results highlight the importance of large-effect standing variants in rapid adaptation, which have been critical to A. artemisiifolias global spread across vast climatic gradients.

evolutionary biology↗

bioRxiv2022

Uncovering the hologenomic basis of an extraordinary plant invasion

While invasive species are a key driver of the global biodiversity crisis, the drivers of invasiveness remain debated. To investigate the genomic basis of invasiveness in plants, we use the invasive weed Ambrosia artemisiifolia, introduced to Europe in the late 19th century, resequencing 655 ragweed genomes, including 308 herbarium specimens collected up to 190 years ago. In introduced European populations, we report selection signatures in defense genes and lower prevalence of particular plant pathogens in the invasive range. Together with temporal changes in population structure associated with introgression from closely related Ambrosia species, escape from microbial enemies likely favoured the plants remarkable success as an invasive species. One-Sentence SummaryThe invasive success of European ragweed was facilitated by release from enemy microbes and inter-species hybridization.

genomics↗