Phylogeography of split kelp Hedophyllum nigripes : northern ice-age refugia and trans-Arctic dispersal
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ORIGINAL PAPER
Phylogeography of split kelp Hedophyllum nigripes: northern ice‑age refugia and trans‑Arctic dispersal W. Stewart Grant1 · Anniken Lydon2 · Trevor T. Bringloe3 Received: 30 September 2019 / Revised: 19 August 2020 / Accepted: 14 September 2020 / Published online: 24 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Pleistocene climate cycles greatly influenced the distributions of kelps in northern seas and gated trans-Arctic dispersals between the North (N) Pacific and N Atlantic oceans. Here, we used partial sequences of the mitochondrial DNA cytochrome oxidase I-5′ (COI) and plastid ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit-3′ (rbcL) to resolve the phylogeography of the kelp Hedophyllum nigripes in the Gulf of Alaska and globally. In the Gulf of Alaska, genetic diversity was moderate (COI: h = 0.493 ± 0.076, n = 57; rbcL: h = 0.578 ± 0.00047, n = 54), but nucleotide diversity was small (COI: θπ = 0.00114 ± 0.00100, n = 57; rbcL: θπ = 0.0001 ± 0.00089, n = 54). Concatenated sequences showed strong haplotypefrequency differences among populations (ΦST = 0.728). The addition of previously published COI sequences from British Columbia showed a general absence of southern haplotypes in the Gulf of Alaska, supporting the conclusion of northern ice-age refugia. COI sequences in Canadian Arctic-Northwestern (NW) Atlantic populations differed by 1–2 mutation from Northeastern (NE) Pacific sequences, and unexpectedly, were marginally more closely related to populations in British Columbia than to geographically intermediate populations in the Gulf of Alaska. COI haplotypes from the Svalbard Archipelago in the NE Atlantic showed no variability and differed by 1–2 mutations from haplotypes in the NW Atlantic. Timecalibrated genetic divergences indicated trans-Arctic dispersal(s) from the N Pacific into the N Atlantic in the mid-Pleistocene. Keywords Hedophyllum nigripes · Kelp · Phylogeography · Trans-arctic dispersal · Mitochondrial DNA · Chloroplast DNA · Bering strait · Pleistocene glaciation
Introduction Historical events and contemporary processes have shaped the genetic structures of populations of kelps at mid to high latitudes. Chief among contemporary processes is the dispersal of propagules, either as planktonic spores, or as drifting Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00300-020-02748-6) contains supplementary material, which is available to authorized users. * W. Stewart Grant [email protected] 1
College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 17101 Point Lena Loop Road, Juneau, AK 99801, USA
2
Department of Biological Sciences, California Polytechnic State University, 1 Grand Ave, San Luis Obispo, San Luis Obispo, CA 93407, USA
3
School of BioSciences, University of Melbourne, Parkville Campus, Melbourne, Victoria 3010, Australia
unattached kelp (Gillespie et al. 2012), that enhances genetic connetivity between populations and seeds emp
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