Biology subjects

Donnellan, S.

Publications and source records attributed to Donnellan, S..

5 recordsLinked to original sources

bioRxiv2024

Evolutionary bursts drive morphological novelty in the world's largest skinks

Animal phenotypes evolve and diverge as a result of differing selective pressures and drift. These processes leave unique signatures in patterns of trait evolution, impacting the tempo and mode of morphological macroevolution. While there is a broad understanding of the history of some organismal traits (e.g. body size), there is little consensus about the evolutionary mode of most others. This includes the relative contribution of prolonged (Darwinian gradualist) and episodic (Simpsonian jump) changes towards the evolution of novel morphologies. Here we use new exon-capture and linear morphological datasets to investigate the tempo and mode of morphological evolution in Australo-Melanesian Tiliquini skinks. We generate a well-supported time-calibrated phylogenomic tree from [~]400 nuclear markers for more than 100 specimens including undescribed diversity, and provide unprecedented resolution of the rapid Miocene diversification of these lizards. By collecting a morphological dataset that encompasses the lizard body plan (19 traits across the head, body, limb, and tail) we are able to identify that most traits evolve conservatively but infrequent evolutionary bursts result in morphological novelty. These phenotypic discontinuities occur via rapid rate increases along individual branches, inconsistent with both gradualistic and punctuated equilibrial evolutionary modes. Instead, this punctuated gradualism has resulted in the rapid evolution of blue-tongued giants and armored dwarves in the [~]20 million years since colonizing Australia. These results outline the evolutionary pathway towards new morphologies and highlight the heterogeneity of evolutionary tempo and mode, even within individual traits.

evolutionary biology↗

bioRxiv2020

Remdesivir-Ivermectin combination displays synergistic interaction with improved in vitro antiviral activity against SARS-CoV-2

A key element for the prevention and management of COVID-19 is the development of effective therapeutics. Drug combination strategies of repurposed drugs offer several advantages over monotherapies, including the potential to achieve greater efficacy, the potential to increase the therapeutic index of drugs and the potential to reduce the emergence of drug resistance. Here, we report on the in vitro synergistic interaction between two FDA approved drugs, remdesivir and ivermectin resulting in enhanced antiviral activity against SARS-CoV-2. These findings warrant further investigations into the clinical potential of this combination, together with studies to define the underlying mechanism.

microbiology↗

bioRxiv2020

A draft genome assembly of the eastern banjo frog Limnodynastes dumerilii dumerilii (Anura: Limnodynastidae)

Amphibian genomes are usually challenging to assemble due to large genome size and high repeat content. The Limnodynastidae is a family of frogs native to Australia, Tasmania and New Guinea. As an anuran lineage that successfully diversified on the Australian continent, it represents an important lineage in the amphibian tree of life but lacks reference genomes. Here we sequenced and annotated the genome of the eastern banjo frog Limnodynastes dumerilii dumerilii to fill this gap. The total length of the genome assembly is 2.38 Gb with a scaffold N50 of 285.9 kb. We identified 1.21 Gb of non-redundant sequences as repetitive elements and annotated 24,548 protein-coding genes in the assembly. BUSCO assessment indicated that more than 94% of the expected vertebrate genes were present in the genome assembly and the gene set. We anticipate that this annotated genome assembly will advance the future study of anuran phylogeny and amphibian genome evolution.

genomics↗

bioRxiv2016

Evolutionary history of the brown rat: out of southern East Asia and selection

The brown rat (Rattus norvegicus) is found wherever humans live and transmits many diseases, and its breeding produced the laboratory rat used widely in medical research. Here, we sequenced whole genomes from 118 rats to explore the origin and dispersal routes of the brown rat and the domestication of the laboratory rat. We showed that brown rats migrated about 3600 years ago from southern East Asia, rather than Northern Asia as formerly suggested, to the Middle East and then to Europe and Africa. Many genes involved in the immune system experienced positive selection in the wild brown rat, while genes involved in the nervous system and energy metabolism showed evidence of artificial selection during the domestication of laboratory strains. Our findings demystify the puzzling origin and migration of brown rats and reveal the impact of evolution and domestication on this animal.

evolutionary biology↗

bioRxiv2016

De-novo emergence and template switching of SINE retroposons during the early evolution of passerine birds

Passeriformes (\"perching birds\" or passerines) make up more than half of all extant bird species. Here, we resolve their deep phylogenetic relationships using presence/absence patterns of short interspersed elements (SINEs), a group of retroposons which is abundant in mammalian genomes but considered largely inactive in avian genomes. The resultant retroposon-based phylogeny provides a powerful and independent corroboration of previous indications derived from sequence-based analyses. Notably, SINE activity began in the common ancestor of Eupasseres (passerines excl. the New Zealand wrens Acanthisittidae) and ceased before the rapid diversification of oscine passerines (songbirds). Furthermore, we find evidence for very recent SINE activity within suboscine passerines, following the emergence of a SINE via acquisition of a different tRNA head as we suggest through template switching. We propose that the early evolution of passerines was unusual among birds in that it was accompanied by activity of SINEs. Their genomic and transcriptomic impact warrants further study in the light of the massive diversification of passerines.

evolutionary biology↗