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Silversword alliance
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<h2 id="characteristics">Characteristics</h2> <p>All members of the silversword alliance are perennials, but otherwise occupy a wide range of ecological niches.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> </p> <h2 id="evolution">Evolution</h2> <p>All Hawaiian tarweeds trace their lineage back to a species of Pacific coast tarweed, very similar to extant species like <i><a href="/facts/Carlquistia_muirii/GqN68Wqd">Carlquistia muirii</a></i>.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> The last common ancestor of the silversword alliance was likely a mat and rhizome forming plant not more than .3 metres (0.98 ft) tall, with a chromosome number of 2<i>n</i> = 16, and perhaps another similar species. Species of <i>Dubautia</i> however have 2<i>n</i> = 14 chromosomes. How the silverswords' chromosome number arose is a matter of some uncertainty, but two major scientific theories have been proposed. One is that two ancestor species, one with <i>n</i> = 6 and one with <i>n</i> = 8 chromosomes hybridized, resulting in a <i>n =</i> 7 hybrid. The hybrid then, by <a href="/facts/Allopolyploid/L7xyKHdK">allopolyploidy</a> doubled its chromosome number spontaneously, leading to the resultant and extant 2<i>n</i> = 14 species. Alternatively, the modern chromosome number could have arisen from an ancestor like <i><a href="/facts/Anisocarpus_scabridus/5F6tcfHJ">Anisocarpus scabridus</a></i>, with a chromosome complement of <i>n =</i> 7, and then arisen by <a href="/facts/Autopolyploidy/L7xyKHdK">autopolyploidy</a>, instead of needing to first hybridize.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> </p> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"Hawaiian silversword alliance, UH Botany". www.botany.hawaii.edu. Retrieved 2019-03-02. <a href="http://www.botany.hawaii.edu/faculty/carr/silversword.htm" target="_blank">http://www.botany.hawaii.edu/faculty/carr/silversword.htm</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Carlquist, S., B. G. Baldwin, and G. D. Carr, eds. 2003. Tarweeds & Silverswords: Evolution of the Madiinae (Asteraceae). Missouri Botanical Garden Press. <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Hawaiian silversword alliance, UH Botany". www.botany.hawaii.edu. Retrieved 2019-03-08. <a href="http://www.botany.hawaii.edu/faculty/carr/silversword.htm" target="_blank">http://www.botany.hawaii.edu/faculty/carr/silversword.htm</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Vickie Caraway, Gerald D. Carr and Clifford W. Morden (2001), "Assessment of hybridization and introgression in lava-colonizing Hawaiian Dubautia (Asteraceae: Madiinae) using RAPD markers", American Journal of Botany, 88 (9): 1688–1694, doi:10.2307/3558414, JSTOR 3558414, PMID 21669703 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Blonder, Benjamin; Baldwin, Bruce G.; Enquist, Brian J.; Robichaux, Robert H. (2016). "Variation and macroevolution in leaf functional traits in the Hawaiian silversword alliance (Asteraceae)" (PDF). Journal of Ecology. 104 (1): 219–228. doi:10.1111/1365-2745.12497. ISSN 1365-2745. <a href="https://escholarship.org/content/qt1wv3d4nb/qt1wv3d4nb.pdf?t=onird7" target="_blank">https://escholarship.org/content/qt1wv3d4nb/qt1wv3d4nb.pdf?t=onird7</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Lawton‐Rauh, A.; Robichaux, R. H.; Purugganan, M. D. (2007). "Diversity and divergence patterns in regulatory genes suggest differential gene flow in recently derived species of the Hawaiian silversword alliance adaptive radiation (Asteraceae)". Molecular Ecology. 16 (19): 3995–4013. doi:10.1111/j.1365-294X.2007.03445.x. ISSN 1365-294X. PMID 17784920. S2CID 18623958. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Friar, Elizabeth A.; McGlaughlin, Mitchell E. (2011-03-01). "Evolutionary diversification and geographical isolation in Dubautia laxa (Asteraceae), a widespread member of the Hawaiian silversword alliance". Annals of Botany. 107 (3): 357–370. doi:10.1093/aob/mcq252. ISSN 0305-7364. PMC 3043929. PMID 21193480. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3043929" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3043929</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Friar, Elizabeth A.; Prince, Linda M.; Cruse-Sanders, Jennifer M.; McGlaughlin, Mitchell E.; Butterworth, Charles A.; Baldwin, Bruce G. (2008). "Hybrid Origin and Genomic Mosaicism of Dubautia scabra (Hawaiian Silversword Alliance; Asteraceae, Madiinae)". Systematic Botany. 33 (3): 589–597. doi:10.1600/036364408785679815. ISSN 0363-6445. JSTOR 40211922. S2CID 86257628. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Sanderson, Michael J.; Baldwin, Bruce G. (1998-08-04). "Age and rate of diversification of the Hawaiian silversword alliance (Compositae)". Proceedings of the National Academy of Sciences. 95 (16): 9402–9406. Bibcode:1998PNAS...95.9402B. doi:10.1073/pnas.95.16.9402. ISSN 0027-8424. PMC 21350. PMID 9689092. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC21350" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC21350</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>For instance, Blonder and Baldwin 2016 cite 33 species, Friar 2011 cites 33, Lawton‐Rauh 2007 cites 30, Sanderson and Baldwin cite 28. <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>"Hawaiian silversword alliance, UH Botany". www.botany.hawaii.edu. Retrieved 2019-03-08. <a href="http://www.botany.hawaii.edu/faculty/carr/habit.htm" target="_blank">http://www.botany.hawaii.edu/faculty/carr/habit.htm</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>"Hawaiian silversword alliance, UH Botany". www.botany.hawaii.edu. Retrieved 2019-03-08. <a href="http://www.botany.hawaii.edu/faculty/carr/habit.htm" target="_blank">http://www.botany.hawaii.edu/faculty/carr/habit.htm</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>"Hawaiian silversword alliance, UH Botany". www.botany.hawaii.edu. Retrieved 2019-03-08. <a href="http://www.botany.hawaii.edu/faculty/carr/origin.htm" target="_blank">http://www.botany.hawaii.edu/faculty/carr/origin.htm</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> </ol>