Redefining the Evolutionary History of the Rock Dove, Columba livia, Using Whole Genome Sequences.

The domestic pigeon's exceptional phenotypic diversity was key in developing Darwin's Theory of Evolution and establishing the concept of artificial selection. However, unlike its domestic counterpart, its wild progenitor, the rock dove Columba livia has received considerably less attention. Therefore, questions regarding its domestication, evolution, taxonomy, and conservation status remain unresolved. We generated whole-genome sequencing data from 65 historical rock doves that represent all currently recognized subspecies and span the species' original geographic distribution. Our dataset includes 3 specimens from Darwin's collection, and the type specimens of 5 different taxa. We characterized their population structure, genomic diversity, and gene-flow patterns. Our results show the West African subspecies C. l. gymnocyclus is basal to rock doves and domestic pigeons, and suggests gene-flow between the rock dove's sister species C. rupestris, and the ancestor of rock doves after its split from West African populations. These genomes allowed us to propose a model for the evolution of the rock dove in light of the refugia theory. We propose that rock dove genetic diversity and introgression patterns derive from a history of allopatric cycles and dispersion waves during the Quaternary glacial and interglacial periods. To explore the rock dove domestication history, we combined our new dataset with available genomes from domestic pigeons. Our results point to at least 1 domestication event in the Levant that gave rise to all domestic breeds analysed in this study. Finally, we propose a species-level taxonomic arrangement to reflect the evolutionary history of the West African rock dove populations.

To bee, or not to bee? One leg is the question.

Temporal genomic studies that utilise museum insects are invaluable for understanding changes in ecological processes in which insects are essential, such as wild and agricultural pollination, seed dispersal, nutrient cycling, and food web architecture, to name a few. However, given such analyses come at the cost of physical damage to museum specimens required for such work, there is a natural interest in the development and/or application of methods to minimise the damage incurred. We explored the efficacy of a recently published single stranded library construction protocol, on DNA extracted from single legs taken from eight dry-preserved historic bee specimens collected 150 years ago. Specifically, the DNA was extracted using a "minimally destructive" method that leaves the samples' exterior intact. Our sequencing data revealed not only that the endogenous DNA recovered from some of the samples was at a relatively high level (up to 58%), but that the complexity of the libraries was sufficient in the best samples to theoretically allow deeper sequencing to a predicted level of 69x genome coverage. As such, these combined protocols offer the possibility to generate sequencing data at levels that are suitable for many common evolutionary genomic analyses, while simultaneously minimising the damage conferred to the valuable dried museum bee samples. Furthermore, we anticipate that these methods may have much wider application on many other invertebrate taxa stored in a similar way. We hope that the results from this research may be able to contribute to the increased willingness of museums to loan much needed dry-preserved insects for future genomic studies.

Dense sampling of bird diversity increases power of comparative genomics.

Whole-genome sequencing projects are increasingly populating the tree of life and characterizing biodiversity1-4. Sparse taxon sampling has previously been proposed to confound phylogenetic inference5, and captures only a fraction of the genomic diversity. Here we report a substantial step towards the dense representation of avian phylogenetic and molecular diversity, by analysing 363 genomes from 92.4% of bird families-including 267 newly sequenced genomes produced for phase II of the Bird 10,000 Genomes (B10K) Project. We use this comparative genome dataset in combination with a pipeline that leverages a reference-free whole-genome alignment to identify orthologous regions in greater numbers than has previously been possible and to recognize genomic novelties in particular bird lineages. The densely sampled alignment provides a single-base-pair map of selection, has more than doubled the fraction of bases that are confidently predicted to be under conservation and reveals extensive patterns of weak selection in predominantly non-coding DNA. Our results demonstrate that increasing the diversity of genomes used in comparative studies can reveal more shared and lineage-specific variation, and improve the investigation of genomic characteristics. We anticipate that this genomic resource will offer new perspectives on evolutionary processes in cross-species comparative analyses and assist in efforts to conserve species.