Abstract Detail

Biogeography

Hooker, Marcus [1], Hufford, Larry [2].

Diversification of Synthyris (Plantaginaceae) in the American West.

Synthyris (Plantaginaceae) are herbaceous perennials found widely across mountainous areas of western North America but also with a disjunct species in the Great Lakes region and another species in Alaska and the Yukon. Synthyris has three major clades, including the high latitude clade that is sister to the Northwest clade and an Intermountain clade, which is sister to the other two clades. This study addresses (1) the age and ancestral area of Synthyris; (2) clade divergence times and historical factors, such as climate and geology, that were involved in cladogenesis; and (3) patterns of geographic radiation. We reconstructed a time-calibrated phylogeny of the genus using ITS sequence data from all species within Synthyris and applied a statistical dispersal-vicariance model to reconstruct the biogeographic history of the group. The results indicate that Synthyris diverged from other Plantaginaceae in the early to middle Miocene (23.5-10.4 MYA). The stem lineage was reconstructed as geographically widespread in the American West, ranging from high latitudes to southern Nevada, prior to crown diversification. Early cladogenesis in Synthyris may have resulted from warming and drying that drove populations into higher elevation environments in the southwestern part of its range. The intermountain clade diversified in the late Miocene to Pliocene 10-2.3 MYA along the eastern margin of Great Basin before migrating northward into the Pacific Northwest, where it is represented by S. missuria, which adopted a new ecological niche. The high latitude clade, consisting only of S. borealis, and the relatively species rich and geographically widespread Northwest clade diverged 14.5-6.5 MYA from a widespread Rocky Mountain ancestor. The disjunct distribution of S. borealis, which is restricted to unglaciated areas of Alaska and the Yukon, is likely a consequence of the Pleistocene continental glaciations. The Northwest clade, which was reconstructed as having an ancestral area in the Rocky Mountains, diverged in the late Miocene 12.6-5.3 MYA and subsequently expanded its range southward along the Rocky Mountains, eastward to the Great Lakes, and westward into the Pacific Northwest. Timing of much of the diversification within the Northwest clade largely corresponds to the Pleistocene epoch and was likely a result of widespread glaciations and climatic fluctuations during this time. Such speciation events include the origin of S. canbyi and the interspecific hybridization that led to S. ritteriana.

1 - Washington State University, School of Biological Sciences, 2518 NW Short Dr, Pullman, WA, 99164, USA
2 - Washington State University, SCHOOL OF BIOLOGICAL SCIENCES, 312 Abelson Hall, PULLMAN, WA, 99164-4236, USA

Keywords:
Biogeography
Plantaginaceae
Systematics
Montane.

Presentation Type: Oral Paper
Session: 37, Biogeography II
Location: 103/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 8:15 AM
Number: 37002
Abstract ID:447
Candidate for Awards:None