Abstract Detail

Biogeography

Stubbs, Rebecca [1], Folk, Ryan [1], Soltis, Douglas E. [1], Cellinese, Nico [1].

Investigating the Sierra Nevada-Rocky Mountain disjunction in Micranthes (Saxifragaceae) with a target enrichment approach.

Micranthes (Saxifragaceae) provides a unique system for investigating the poorly known Sierra Nevada-Rocky Mountain disjunction in both a systematic and biogeographic context. Within Micranthes, two divergent taxa, M. bryophora and M. tolmiei, show this pattern though they differ phylogenetically, morphologically and ecologically. Micranthes tolmiei has a widespread distribution covering the Sierra Nevada through the Cascade ranges plus also occurring in the northern Rocky Mountains. It grows exclusively above tree line and is morphologically unique as the only species in Micranthes with truly succulent leaves. Micranthes bryophora, by contrast, is a narrow endemic restricted to the Sierra Nevada and also a few populations, found within a 35 km radius of each other, in the Rocky Mountains of Idaho. This taxon is found in mid- to high-elevations in temperate forests and shares many morphological similarities with other taxa throughout Micranthes. The diversity of this system along phenotypic and geographic axes therefore allows us to address multiple facets of this disjunction. Why do these two taxa show this disjunction although they are distantly related within this clade, morphologically distinct, and show overall different distribution patterns? Could this be explained by different mechanisms of vicariance or different times of dispersal for these congeneric taxa? Is this an example of biogeographical congruence (result of a common process) or pseudocongruence (result of different processes and/or times)? To address these hypotheses, we used 596 putatively single copy nuclear loci and the majority of the plastome to detect population structure among multiple accessions of both taxa. In the nuclear phylogeny, within both M. tolmiei and M. bryophora we recover Rocky Mountain and Cascades/Sierra Nevada accessions as reciprocally monophyletic groups. In the plastid dataset, the relationships in M. tolmiei are congruent with nuclear data, yet Rocky Mountain and Sierra Nevada clades are not recovered in M. bryophora. Our dated phylogeny shows that the M. tolmiei disjunction is older than the M. bryophora disjunction, and ecological niche modeling suggests differences in habitat suitability between plants found in the Sierra Nevada and Rocky Mountains. With this research we will provide new insight into this lesser-known disjunction and demonstrate the use of Next Generation Sequencing for investigating population-level questions.

Related Links:
Micranthes (Saxifragaceae) research website

1 - University of Florida, Florida Museum of Natural History, 1659 Museum Road, Gainesville, Florida, 32611, United States

Keywords:
Micranthes
Saxifragaceae
Sierra Nevada
Rocky Mountains
phylogenomics
ecological niche modeling.

Presentation Type: Oral Paper
Session: 13, Biogeography
Location: Sundance 3/Omni Hotel
Date: Monday, June 26th, 2017
Time: 1:30 PM
Number: 13001
Abstract ID:122
Candidate for Awards:None