RESEARCH
Conservation GENOMICS
Norfolk Robins are a cryptic endangered species
Norfolk Robins (Petroica multicolor) are restricted to isolated Norfolk Island in the Pacific. Using mtDNA from historical museum specimens we showed that rather than being one of 15 subspecies of Pacific Robin (now P. pusilla and P. polymorpha) or combined also with Australia's Scarlet Robin (now P. boodang), the Norfolk Robin is actually a distinct species. Our work resulted in the taxonomic re-classification of the rest of the Pacific robins as Petroica pusilla (Kearns et al. 2016 Cons Gen; with further subdivisions proposed in Kearns et al. 2020 J. Av. Biol.). Since there are likely fewer than 500 breeding pairs of Norfolk Robins, our proposed taxonomic change had significant implications for the conservation of this species--resulting in its recognition as an endangered species by the IUCN. A re-examination of its conservation management plan is now required.
Publications
Impact of avian malaria on Hawaii's threatened birds: insights from historical museum specimens
Focusing on Hawaii and Oahu amakihis we are using genome-wide SNPs acquired via hybridization capture to explore differences in genetic diversity and adaptation in specimens collected before and after avian malaria arrived in Hawaii.
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Conservation genomics of the critically endangered Saipan reedwarbler
Three species of reedwarbler went extinct on the Mariana Islands from the 1960 to the 1990s (Acrocephalus luscinius on Guam, A. yamashinae on Pagan and A. nijoi on Aguijan), leaving just the critically endangered A. hiwae on Saipan and Alamagan remaining. In order to provide a framework for conservation efforts, we used genome-wide SNPs and mtDNA to (a) test if Saipan and Alamagan populations are genetically distinct enough to warrant subspecies recognition or separate conservation management, (b) determine if either Saipan and Alamagan populations exhibit geographic structuring, and (c) compare genetic diversity and inbreeding levels in Saipan and Alamagan populations.
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SPECIATION & EVOLUTIONARY HISTORY
Speciation reversal and reticulate histories of ravens in North America
Using mtDNA and genome-wide SNPs we showed that Common Ravens in the western US have mosaic hybrid genomes formed from lineage fusion/speciation reversal between two formerly distinct lineages (Kearns et al. 2018, Nature Communications). Continuing this research as a Smithsonian Biodiversity Genomics Postdoctoral Fellow my goal was to explore the timing of speciation reversal by using ancient DNA approaches to explore the extent of hybridization, geographic distribution and diversity of raven lineages during two historical time-periods: 100 ya and ~5000 ya. To do this, I am using genomic sequence capture techniques to obtain thousands of variable regions from the genomes of raven specimens that were collected by museums in the late 1800s and early 1900s, and from subfossil bones. In collaboration with Dr. Maria Nandadevi Cortes-Rodriguez at Ithaca College, we are also attempting to obtain the first phylogeographic-level sampling for Mexico and Central America in order to determine the frequency and southern extent of the Holarctic lineage, and the taxonomic distinctiveness of Corvus corax clarionensis from the Revillagigedo Archipelago off the coast of Mexico.
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Complex spatio-temporal signatures of dispersal, colonization and hybridization among the Acrocephalus reedwarblers of the Pacific
Acrocephalus reed warblers have colonized and speciated across the Pacific. Previous work by Cibois et al. (2011) found odd biogeographic patterns and paraphyletic species based on mtDNA. Here at the Smithsonian's Center for Conservation Genomics I am working on developing a dataset of SNPs randomly sampled across the nuclear genome and a dataset of potential adaptive and plumage-linked genes in order to explore the evolutionary history, phylogenomics and population genomics of the Pacific reed warblers.
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Speciation history and taxonomy of the Petroica robins of Australia, New Guina and the Pacific
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The role of climate change in shaping the evolutionary history of Austro-Papuan birds
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Few modern tissue samples are available for Pacific robins, therefore we relied heavily on historical collections held at the American Museum of Natural History, the Delaware Museum of Natural History, University of Kansas Natural History Museum and the Academy of Natural Sciences. We integrated ancient DNA, morphometrics and plumage spectrophotometry from all described subspecies of the Pacific Robin, and putative close relatives in Australia in our taxonomic revision. Key insights so far include: (1) Finding that the Norfolk Island Robin (long thought to be one of 15 subspecies) is a distinct endangered species (Petroica multicolor). (2) Finding that Pacific robins on Tanna and Aneityum islands in Vanuatu are morphologically and genetically distinct, resulting in the description of a new subspecies for the population on Tanna Island, P. p. tannensis (Kearns et al. 2015 Emu).
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My work on birds of the Australo-Papuan region began with my Bachelor of Science Honors project at the Australian National University where I used genetics and plumage spectrophotometry measured from historical museum specimens to examine the evolutionary history and taxonomy of Australia's arid-adapted Splendid Fairy-wren (Malurus splendens). A major question was to test the impact that environment change, particularly aridification, had in shaping evolutionary history and taxonomic diversity. I continued this research focus during my PhD at the University of Queensland where I used the Australo-Papuan butcherbirds and magpies (Cracticus and Gymnorhina) to test the relative impact of palaeoenvironmental changes on the population history of closely related species with different habitat preferences.
I particularly focused on the biogeographic and demographic consequences of major changes in climate and landscape during the Pliocene and Pleistocene (5.3 Ma - 11, 700 ya) on the (1) widespread open-habitat generalist Pied Butcherbird (Cracticus nigrogularis), (2) rainforest and mangrove restricted Black Butcherbird (C. quoyi), and (3) the white-throated butcherbird species-group that has three allopatric species distributed in monsoonal savanna (Black-backed Butcherbird, C. mentalis and Silver-backed Butcherbird, C. argenteus), and arid, semi-arid and temperate forests and woodlands (Grey Butcherbird, C. torquatus). |
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