J. Joseph Giersch
Debra S. Finn
Lusha M. Tronstad
Steve Jordan
Larry Serpa
Ronald Call
Clint C. Muhlfeld
David W. Weisrock
Scott Hotaling
2019
<ol class=""><li>Comparative population genetic studies provide a powerful means for assessing the degree to which evolutionary histories may be congruent among taxa while also highlighting the potential for cryptic diversity within existing species.</li><li>In the Rocky Mountains, three confamilial stoneflies (<i>Zapada glacier<span> </span></i>,<i><span> </span>Lednia tumana<span> </span></i>, and<span> </span><i>Lednia tetonica<span> </span></i>; Plecoptera, Nemouridae) occupy cold alpine streams that are primarily fed by melting ice.<span> </span><i>Lednia tumana<span> </span></i>and<span> </span><i>L. tetonica<span> </span></i>are sister species diagnosed from systematic morphological differences, and they are endemic to areas surrounding Glacier National Park and Grand Teton National Park, respectively, in the U.S. Rocky Mountains.<span> </span><i>Zapada glacier<span> </span></i>is also present in alpine streams from Glacier National Park to the Teton Range, sometimes co‐occurring with either<span> </span><i>Lednia<span> </span></i>species.</li><li>We used mitochondrial sequence data to clarify species boundaries, compare population genetic patterns, and test demographic models in a coalescent framework for the three stoneflies. We addressed four questions: (1) Is there genetic support for the morphology‐based species boundaries in<span> </span><i>Lednia<span> </span></i>? (2) Is there genetic support for cryptic, or as‐yet undescribed, diversity within<span> </span><i>Z. glacier<span> </span></i>? (3) Do similar geographic distributions and ecological requirements yield spatial congruence of genetic structure between high‐elevation<span> </span><i>Lednia<span> </span></i>and<span> </span><i>Z. glacier<span> </span></i>populations? (4) Is there evidence for contemporary gene flow among isolated populations in either group?</li><li>Our results supported the existing taxonomy with<span> </span><i>Z. glacier<span> </span></i>and the two<span> </span><i>Lednia<span> </span></i>species differing in their depths of divergence among study regions (e.g. maximum sequence divergence within<span> </span><i>Z. glacier<span> </span></i> = 1.2% versus 5% between<span> </span><i>L. tumana<span> </span></i>and<span> </span><i>L. tetonica<span> </span></i>). However, spatial population genetic patterns were broadly congruent, indicating stonefly populations isolated on mountaintop islands. Coalescent modelling supported the possibility of rare, extremely limited contemporary gene flow among<span> </span><i>Z. glacier<span> </span></i>populations, with no support for gene flow between<span> </span><i>L. tumana<span> </span></i>and<span> </span><i>L. tetonica<span> </span></i>.</li><li>The focal stoneflies and associated assemblages occupy the highest elevation, coldest permanent alpine streams in the study region. This lotic habitat type faces an uncertain future under a diminishing alpine cryosphere. Given spatial congruence of genetic structure demonstrating unique biodiversity associated with individual alpine islands, we encourage conservation management strategies be developed and applied at corresponding spatial scales.</li></ol>
application/pdf
10.1111/fwb.13223
en
Wiley
Congruent population genetic structure but differing depths of divergence for three alpine stoneflies with similar ecology and geographic distributions
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