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Genomic evidence of an ancient inland temperate rainforest in the Pacific Northwest of North America

The disjunct temperate rainforests of the Pacific Northwest of North America (PNW) are characterized by late‐successional dominant tree species Thuja plicata (western redcedar) and Tsuga heterophylla (western hemlock). The demographic histories of these species, along with the PNW rainforest ecosyst...

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Autores principales: Ruffley, Megan, Smith, Megan L., Espíndola, Anahí, Turck, Daniel F., Mitchell, Niels, Carstens, Bryan, Sullivan, Jack, Tank, David C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9322681/
https://www.ncbi.nlm.nih.gov/pubmed/35322900
http://dx.doi.org/10.1111/mec.16431
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author Ruffley, Megan
Smith, Megan L.
Espíndola, Anahí
Turck, Daniel F.
Mitchell, Niels
Carstens, Bryan
Sullivan, Jack
Tank, David C.
author_facet Ruffley, Megan
Smith, Megan L.
Espíndola, Anahí
Turck, Daniel F.
Mitchell, Niels
Carstens, Bryan
Sullivan, Jack
Tank, David C.
author_sort Ruffley, Megan
collection PubMed
description The disjunct temperate rainforests of the Pacific Northwest of North America (PNW) are characterized by late‐successional dominant tree species Thuja plicata (western redcedar) and Tsuga heterophylla (western hemlock). The demographic histories of these species, along with the PNW rainforest ecosystem in its entirety, have been heavily impacted by geological and climatic changes the PNW has experienced over the last 5 million years, including mountain orogeny and repeated Pleistocene glaciations. These environmental events have ultimately shaped the history of these species, with inland populations potentially being extirpated during the Pleistocene glaciations. Here, we collect genomic data for both species across their ranges to test multiple demographic models, each reflecting a different phylogeographical hypothesis on how the ecosystem‐dominating species may have responded to dramatic climatic change. Our results indicate that inland and coastal populations in both species diverged ~2.5 million years ago in the early Pleistocene and experienced decreases in population size during glacial cycles, with subsequent population expansion. Importantly, we found evidence for gene flow between coastal and inland populations during the mid‐Holocene. It is likely that intermittent migration in these species during this time has prevented allopatric speciation via genetic drift alone. In conclusion, our results from combining genomic data and demographic inference procedures establish that populations of the ecosystem dominants Thuja plicata and Tsuga heterophylla persisted in refugia located in both the coastal and inland regions of the PNW throughout the Pleistocene, with populations expanding and contracting in response to glacial cycles with occasional gene flow.
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spelling pubmed-93226812022-07-30 Genomic evidence of an ancient inland temperate rainforest in the Pacific Northwest of North America Ruffley, Megan Smith, Megan L. Espíndola, Anahí Turck, Daniel F. Mitchell, Niels Carstens, Bryan Sullivan, Jack Tank, David C. Mol Ecol Original Articles The disjunct temperate rainforests of the Pacific Northwest of North America (PNW) are characterized by late‐successional dominant tree species Thuja plicata (western redcedar) and Tsuga heterophylla (western hemlock). The demographic histories of these species, along with the PNW rainforest ecosystem in its entirety, have been heavily impacted by geological and climatic changes the PNW has experienced over the last 5 million years, including mountain orogeny and repeated Pleistocene glaciations. These environmental events have ultimately shaped the history of these species, with inland populations potentially being extirpated during the Pleistocene glaciations. Here, we collect genomic data for both species across their ranges to test multiple demographic models, each reflecting a different phylogeographical hypothesis on how the ecosystem‐dominating species may have responded to dramatic climatic change. Our results indicate that inland and coastal populations in both species diverged ~2.5 million years ago in the early Pleistocene and experienced decreases in population size during glacial cycles, with subsequent population expansion. Importantly, we found evidence for gene flow between coastal and inland populations during the mid‐Holocene. It is likely that intermittent migration in these species during this time has prevented allopatric speciation via genetic drift alone. In conclusion, our results from combining genomic data and demographic inference procedures establish that populations of the ecosystem dominants Thuja plicata and Tsuga heterophylla persisted in refugia located in both the coastal and inland regions of the PNW throughout the Pleistocene, with populations expanding and contracting in response to glacial cycles with occasional gene flow. John Wiley and Sons Inc. 2022-04-09 2022-05 /pmc/articles/PMC9322681/ /pubmed/35322900 http://dx.doi.org/10.1111/mec.16431 Text en © 2022 The Authors. Molecular Ecology published by John Wiley & Sons Ltd. https://creativecommons.org/licenses/by-nc/4.0/This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc/4.0/ (https://creativecommons.org/licenses/by-nc/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
spellingShingle Original Articles
Ruffley, Megan
Smith, Megan L.
Espíndola, Anahí
Turck, Daniel F.
Mitchell, Niels
Carstens, Bryan
Sullivan, Jack
Tank, David C.
Genomic evidence of an ancient inland temperate rainforest in the Pacific Northwest of North America
title Genomic evidence of an ancient inland temperate rainforest in the Pacific Northwest of North America
title_full Genomic evidence of an ancient inland temperate rainforest in the Pacific Northwest of North America
title_fullStr Genomic evidence of an ancient inland temperate rainforest in the Pacific Northwest of North America
title_full_unstemmed Genomic evidence of an ancient inland temperate rainforest in the Pacific Northwest of North America
title_short Genomic evidence of an ancient inland temperate rainforest in the Pacific Northwest of North America
title_sort genomic evidence of an ancient inland temperate rainforest in the pacific northwest of north america
topic Original Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9322681/
https://www.ncbi.nlm.nih.gov/pubmed/35322900
http://dx.doi.org/10.1111/mec.16431
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