ORCID Profile
0000-0002-7220-5588
Current Organisations
University of New Mexico
,
Museum of Southwestern Biology
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Publisher: Informa UK Limited
Date: 20-12-2020
Publisher: Wiley
Date: 31-03-2021
DOI: 10.1111/MEC.15856
Abstract: Hybridization, introgression, and reciprocal gene flow during speciation, specifically the generation of mitonuclear discordance, are increasingly observed as parts of the speciation process. Genomic approaches provide insight into where, when, and how adaptation operates during and after speciation and can measure historical and modern introgression. Whether adaptive or neutral in origin, hybridization can cause mitonuclear discordance by placing the mitochondrial genome of one species (or population) in the nuclear background of another species. The latter, introgressed species may eventually have its own mtDNA replaced or “captured” by other species across its entire geographical range. Intermediate stages in the capture process should be observable. Two nonsister species of Australasian monarch‐flycatchers, Spectacled Monarch ( Symposiachrus trivirgatus ) mostly of Australia and Indonesia and Spot‐winged Monarch ( S. guttula ) of New Guinea, present an opportunity to observe this process. We analysed thousands of single nucleotide polymorphisms (SNPs) derived from ultraconserved elements of all subspecies of both species. Mitochondrial DNA sequences of Australian populations of S. trivirgatus form two paraphyletic clades, one being sister to and presumably introgressed by S. guttula despite little nuclear signal of introgression. Population genetic analyses (e.g., tests for modern and historical gene flow and selection) support at least one historical gene flow event between S. guttula and Australian S. trivirgatus . We also uncovered introgression from the Maluku Islands subspecies of S. trivirgatus into an island population of S. guttula , resulting in apparent nuclear paraphyly. We find that neutral demographic processes, not adaptive introgression, are the most likely cause of these complex population histories. We suggest that a Pleistocene extinction of S. guttula from mainland Australia resulted from range expansion by S. trivirgatus .
Publisher: Wiley
Date: 12-04-2019
DOI: 10.1111/ZSC.12350
Publisher: Proceedings of the National Academy of Sciences
Date: 04-2019
Abstract: Avian ersification has been influenced by global climate change, plate tectonic movements, and mass extinction events. However, the impact of these factors on the ersification of the hyper erse perching birds (passerines) is unclear because family level relationships are unresolved and the timing of splitting events among lineages is uncertain. We analyzed DNA data from 4,060 nuclear loci and 137 passerine families using concatenation and coalescent approaches to infer a comprehensive phylogenetic hypothesis that clarifies relationships among all passerine families. Then, we calibrated this phylogeny using 13 fossils to examine the effects of different events in Earth history on the timing and rate of passerine ersification. Our analyses reconcile passerine ersification with the fossil and geological records suggest that passerines originated on the Australian landmass ∼47 Ma and show that subsequent dispersal and ersification of passerines was affected by a number of climatological and geological events, such as Oligocene glaciation and inundation of the New Zealand landmass. Although passerine ersification rates fluctuated throughout the Cenozoic, we find no link between the rate of passerine ersification and Cenozoic global temperature, and our analyses show that the increases in passerine ersification rate we observe are disconnected from the colonization of new continents. Taken together, these results suggest more complex mechanisms than temperature change or ecological opportunity have controlled macroscale patterns of passerine speciation.
Publisher: Wiley
Date: 29-07-2023
DOI: 10.1111/MEC.17080
Abstract: Many organisms possess multiple discrete genomes (i.e. nuclear and organellar), which are inherited separately and may have unique and even conflicting evolutionary histories. Phylogenetic reconstructions from these discrete genomes can yield different patterns of relatedness, a phenomenon known as cytonuclear discordance. In many animals, mitonuclear discordance (i.e. discordant evolutionary histories between the nuclear and mitochondrial genomes) has been widely documented, but its causes are often considered idiosyncratic and inscrutable. We show that a case of mitonuclear discordance in Todir hus kingfishers can be explained by extensive genome‐wide incomplete lineage sorting (ILS), likely a result of the explosive ersification history of this genus. For these kingfishers, quartet frequencies reveal that the nuclear genome is dominated by discordant topologies, with none of the internal branches in our consensus nuclear tree recovered in % of genome‐wide gene trees. Meanwhile, a lack of inter‐species shared ancestry, non‐significant pairwise tests for gene flow, and little evidence for meaningful migration edges between species, leads to the conclusion that gene flow cannot explain the mitonuclear discordance we observe. This lack of evidence for gene flow combined with evidence for extensive genome‐wide gene tree discordance, a hallmark of ILS, leads us to conclude that the mitonuclear discordance we observe likely results from ILS, specifically deep coalescence of the mitochondrial genome. Based on this case study, we hypothesize that similar demographic histories in other ‘great speciator’ taxa across the Indo‐Pacific likely predispose these groups to high levels of ILS and high likelihoods of mitonuclear discordance.
Publisher: Informa UK Limited
Date: 25-04-2019
Publisher: Informa UK Limited
Date: 02-10-2021
Location: United States of America
No related grants have been discovered for Michael Andersen.