Biology subjects

Miller, M. J.

Publications and source records attributed to Miller, M. J..

22 records · Page 2Linked to original sources

bioRxiv2020

A highly contiguous genome for the Golden-fronted Woodpecker (Melanerpes aurifrons) via a hybrid Oxford Nanopore and short read assembly

BackgroundWoodpeckers are found in nearly every part of the world, absent only from Antarctica, Australasia, and Madagascar. Woodpeckers have been important for studies of biogeography, phylogeography, and macroecology. Woodpeckers hybrid zones are often studied to understand the dynamics of introgression between bird species. Notably, woodpeckers are gaining attention for their enriched levels of transposable elements (TEs) relative to most other birds. This enrichment of TEs may have substantial effects on woodpecker molecular evolution. The Golden-fronted Woodpecker (Melanerpes aurifrons) is a member of the largest radiation of New World woodpeckers. However, comparative studies of woodpecker genomes are hindered by the fact that no high-contiguity genome exists for any woodpecker species. FindingsUsing hybrid assembly methods that combine long-read Oxford Nanopore and short-read Illumina sequencing data, we generated a highly contiguous genome assembly for the Golden-fronted Woodpecker. The final assembly is 1.31 Gb and comprises 441 contigs plus a full mitochondrial genome. Half of the assembly is represented by 28 contigs (contig N50), each of these contigs is at least 16 Mb in size (contig L50). High recovery (92.6%) of bird-specific BUSCO genes suggests our assembly is both relatively complete and relatively accurate. Accuracy is also demonstrated by the recovery of a putatively error-free mitochondrial genome. Over a quarter (25.8%) of the genome consists of repetitive elements, with 287 Mb (21.9%) of those elements assignable to the CR1 superfamily of transposable elements, the highest proportion of CR1 repeats reported for any bird genome to date. ConclusionOur assembly provides a useful tool for comparative studies of molecular evolution and genomics in woodpeckers and allies, a group emerging as important for studies on the role that TEs may play in avian evolution. Additionally, the sequencing and bioinformatic resources used to generate this assembly were relatively low-cost and should provide a direction for the development of high-quality genomes for future studies of animal biodiversity.

genomics↗

bioRxiv2019

CelltrackR: an R package for fast and flexible analysis of immune cell migration data

SummaryVisualization of cell migration via time-lapse microscopy has greatly advanced our understanding of the immune system. However, subtle differences in migration dynamics are easily obscured by biases and imaging artifacts. While several analysis methods have been suggested to address these issues, an integrated tool implementing them is currently lacking. Here, we present CelltrackR, an R package containing a diverse set of state-of-the-art analysis methods for (immune) cell tracks. CelltrackR supports the complete pipeline for track analysis by providing methods for data management, quality control, extracting and visualizing migration statistics, clustering tracks, and simulating cell migration.\n\nAvailability and ImplementationCelltrackR is an open-source package released under the GPL-2 license, and is freely available on GitHub at https://github.com/ingewortel/celltrackR.\n\nContactmmiller23@wustl.edu, Johannes.Textor@radboudumc.nl

bioinformatics↗

bioRxiv2019

Phylogenomics clarifies biogeographic and evolutionary history, and conservation status of West Indian tremblers and thrashers (Aves: Mimidae)

The West Indian avifauna has provided fundamental insights into island biogeography, taxon cycles, and the evolution of avian behavior. Our interpretations, however, rely on robust hypotheses of evolutionary relationships and consistent conclusions about taxonomic status in groups with many endemic island populations. Here we present a phylogenetic study of the West Indian thrashers, tremblers, and allies, an assemblage of at least 5 species found on 29 islands, which is considered the archipelagos only avian radiation. We improve on previous phylogenetic studies of this group by using double-digest restriction site-associated DNA sequencing (ddRAD-seq) to broadly sample loci scattered across the nuclear genome. A variety of analyses, based on either nucleotide variation in 2,223 loci that were recovered in all samples or on 13,282 loci that were confidently scored as present or absent in all samples, converged on a single well-supported phylogenetic hypothesis. In contrast to previous studies, we found that the resident West Indian taxa form a monophyletic group, exclusive of the Neotropical-Nearctic migratory Gray Catbird Dumetella carolinensis, which breeds in North America. Earlier studies indicated that the Gray Catbird was nested within a clade of island resident species. Instead, our findings imply a single colonization of the West Indies without the need to invoke a subsequent reverse colonization of the mainland by West Indian taxa. Furthermore, our study is the first to sample both endemic subspecies of the endangered White-breasted Thrasher Ramphocinclus brachyurus. We find that these subspecies have a long history of evolutionary independence with no evidence of gene flow, and are as genetically divergent from each other as other genera in the group. These findings support recognition of R. brachyurus (restricted to Martinique) and the Saint Lucia Thrasher R. sanctaeluciae as two distinct, single-island endemic species, and indicate the need to re-evaluate conservation plans for these taxa. Our results demonstrate the utility of phylogenomic datasets for generating robust systematic hypotheses.

evolutionary biology↗

bioRxiv2018

Mitochondrial genomes and phylogenetic analysis of Central American weakly-electric fishes: Apteronotus rostratus, Brachyhypopomus occidentalis and Sternopygus dariensis

Electric fishes are a diverse group of freshwater organisms with the ability to generate electric organ discharges (EODs) that are used for communication and electrolocation. Over 200 species have originated in South America, but of these, only a few have managed to colonize the Central American Isthmus. Here, we assembled two complete and one nearly complete mitochondrial genomes (mitogenomes) for three Central American Gymnotiformes: Sternopygus dariensis, Brachyhypopomus occidentalis and Apteronotus rostratus. We then explored the three species phylogenetic position in the context of South American electric fishes. Mitogenomes were organized in the standard fish mitogenome order, and presented sizes of 16,600, 16,540 and 15,940 base pairs (bp) (nearly complete) for S. dariensis, B. occidentalis and A. rostratus, respectively. We uncovered a novel 60 bp intergenic spacer (IGS) located between the COII and tRNALys genes, which appears to be unique to the Apteronotidae. Furthermore, phylogenetic relationships supported the traditional monophyly of Gymnotiformes, with the three species positioned within their respective family. In addition, the genus Apteronotus was placed as the basal taxon of the order. Finally, we found high sequence divergence (13.3%) between our B. occidentalis specimen and a sequence previously reported in GenBank, suggesting that the prior mitogenome of B. occidentalis represents a different South American species that was misidentified. Indeed, phylogenetic analyses using Cytochrome b gene across the genus placed the previously reported individual within B. bennetti. Our study provides novel mitogenome resources that will advance our understanding of the diversity and phylogenetic history of Neotropical fishes.

evolutionary biology↗