Abstract Detail

Systematics

Imwattana, Karn [1], Shaw, A. Jonathan [1].

Species delimitation in the Sphagnum capillifolium complex in North America.

The Sphagnum capillifolium complex is a group of 6 - 12 closely related peatmoss species which has circumboreal distributions. There are currently 6 widely recognized species based on both morphology and molecular data: S. capillifolium, S. fuscum, S. quinquefarium, S. rubellum, and S. warnstorfii. However, there are at least another 6 described species that are poorly understood maybe a distinct species or maybe a part of the 6 widely recognized species. Because of the ecological importance of Sphagnum for community ecology and biogeochemistry of peatlands, accurate species delimitation is relevant to a broad range of researchers. To test species hypotheses, we used RAD-sequencing to get genome-wide SNP data from eastern and western North American samples of the S. capillifolium complex. We used 2 coalescent based methods, Genealogical Divergence Index (gdi) and Bayes Factor Delimitation (BFD), to test hypotheses about species delimitation. Six poorly understood species were evaluated: 3 species from eastern North America (S. barlettianum, S. beothuk, and S. subtile) and 3 species from western North America (S. sitchense, S. talbotianum, and S. wilfii). For eastern North American putative species, both gdi and BFD supported the split of S. beothuk from S. fuscum while rejected the split of S. barlettianum from S. rubellum and S. subtile from S. capillifolium. Moreover, neither S. barlettianum and S. subtile formed monophyletic clade within S. rubellum and S. capillifolium, respectively. All the species included in this study that has ranges spanning both eastern and western North America showed phylogenetic differentiation between eastern and western populations. Thus, western North American samples of S. capillifolium, S. rubellum, and S. warnstorfii were grouped with the putative species S. sitchense, S. wilfii, and S. talbotianum, respectively. Both BFD and gdi gave weak to moderate support for the split of S. sitchense from eastern S. capillifolium, S.wilfii from eastern S. rubellum, and S. talbotianum from eastern S. warnstorfii. It is still unclear whether putative species from western North America should be warranted a species status. More samples from western North America, and additional morphological comparisons are needed to further evaluate the status of S. sitchense, S. talbotianum, and S. wilfii.

1 - Duke University, Biology, 130 Science Drive, Durham, North Carolina, 27708, United States

Keywords:
Sphagnum
species delimitation
RAD sequecing
Bayes Factor Delimitation
Genealogical Divergence Index.

Presentation Type: Poster
Session: P, Systematics Posters
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 5:00 PM Time and date to be determined
Number: PSY012
Abstract ID:418
Candidate for Awards:None