Abstract Detail

Pteridology

Sirimalwatta, V.N.S. [1], Wolf, Paul [2], Rowe, Carol [2], Ranker, T. A.  [1], Wood, Kenneth R. [3], Morden, C. W.  [1].

Genomic diversity of the Hawaiian endemic Oreogrammitis hookeri (Polypodiaceae).

The flora of the Hawaiian Islands is well known for harboring a variety of polymorphic complexes comprising morphologically divergent populations that are each treated as either distinct species or as part of highly variable single species. Perhaps the best-known example is that of Metrosideros polymorpha Gaudich. (Myrtaceae) with many recognized varieties, and where questions of the specific status of each are a constant source of investigation. Although the polymorphic nature of many such complexes is obvious based on gross morphology, others are far more cryptic. We have conducted a study that has revealed such a cryptic complex among populations of the widespread Hawaiian endemic Oreogrammitis hookeri (Brack.) Parris (Polypodiaceae). An earlier study of isozyme variation among populations of O. hookeri from Maui and Hawai'i Island revealed that the populations on different islands harbored low-frequency private alleles and individuals from the slopes of K?lauea were significantly divergent from those on nearby Mauna Loa, hinting at the possibility of incipient speciation or the existence of cryptic species. The current study was conducted to explore in more detail the genetic diversity and potential divergence among populations typically treated as O. hookeri, and specifically to see if we could find evidence of cryptic species. We used double digest Restriction-site Associated DNA sequencing (ddRADseq) to assess variation among 81 individuals from ten sampling locations from the islands of Kaua?i, O?ahu, Maui, Moloka?i and Hawai'i. We recovered 176 polymorphic loci, which we examined using Structure and Discriminant Analysis of Principle Components (DAPC). We found support for three clusters, one of which was almost restricted to the island of O?ahu. Maui populations showed mixed ancestry where the samples nested in all three clusters. We propose that Maui populations have high gene flow from each of the other sampled islands. On the other hand, Hawai'i, O?ahu and Kaua'i populations are diverging from each other, possibly forming genetically distinct lineages. In contrast, a population on the southwest slope of the Kilauea volcano on Hawai'i was distinct from other populations on Hawai'i, even though they were located nearby. The genetic distinction of this population may be an effect of random genetic drift in small populations or an adaptation to volcanic habitat. In conclusion, O. hookeri may represent a cryptic species complex, or incipient species.

1 - University of Hawaii at Manoa, Department of Botany, 3190 Maile Way, Honolulu, HI, 96822, USA
2 - Utah State University, Department of Biology, 5305 Old Main Hill, Logan, UT, 84322, USA
3 - National Tropical Botanical Garden, 3530 Papalina Road, Kalaheo, HI, 96741, USA

Keywords:
cryptic species
private alleles
incipient species.

Presentation Type: Oral Paper
Session: 32, Pteridology III
Location: 105/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 4:00 PM
Number: 32008
Abstract ID:791
Candidate for Awards:Edgar T. Wherry award