Abstract Detail

Bryology and Lichenology

Cook, Megan [1], Leavitt, Steven [2], ST CLAIR, LARRY L [3].

Disjunct intercontinental populations of lichen-forming fungi – relicts of past continuous distributions or the result of long-distance dispersal?

Floristic similarities in widely disjunct geographic regions have long fascinated biologists. In North America, striking examples include Asa Gray’s famous connections between eastern North America and eastern Asia and the Altai-Rocky Mountain floristic connections. More recently, botanists have examined compelling examples demonstrating disjunct distribution patterns between the Intermountain West of North America and Central Asia for many species. These similarities are especially apparent in alpine, subalpine, and desert-steppe floras. However, due to limited information on the temporal scale of divergences and genetic population structure for most lineages, the origin of widely disjunct populations in the intermountain western region of North America (Intermountain West) and Central Asia remains unclear. Two general explanations prevail: 1) Species with disjunct populations had more contiguous distributions during the Tertiary period, with connections between North America and Asia, e.g., via Beringia or the North Pole by way of Greenland. In fact, the Rocky Mountain flora has been characterized as “a microcosm of its rich Middle Asiatic counterpart,” with the present disjunctions representing relictual populations of a once widely distributed Oroboreal flora. The alternative explanation: 2) Is that disjunct populations are a result of long-distance dispersal events or migration into ecologically similar, disjunct regions. Using a number of lichen-forming fungal species common to western North America and Central Asia, we have investigated the hypothesized roles of long-distance dispersal vs. relicts of past continuous distributions for explaining contemporary distribution patterns. In many cases, molecular sequence data support broad, intercontinental lineages of lichen-forming fungal lineages with no evidence of phylogeographic differentiation among populations. Furthermore, divergence time estimates indicate that a number of disjunct species of lichen-forming fungi share a most recent common ancestor well after the end of the Tertiary period. Taken together, these results suggest that effective long-distance dispersal/migration during the Pleistocene played an important role in creating these impressive disjunct populations in the Intermountain West and Central Asia.

1 - Brigham Young University, Exercise Sciences and ML Bean Life Science Museum, 1115 mlbm , Provo, UT, 84602, USA
2 - Brigham Young University, Department of Biology & M. L. Bean Life Science Museum, 4143 Life Science Building, Provo, UT, 84602, USA
3 - Brigham Young University, Biology and M.L. Bean Life Science Museum, 1115 M.L. Bean Life Science Museum, Brigham Young University, Provo, Utah, 84602, USA

Keywords:
biogeography
Psora
Rhizoplaca
Xanthoparmelia
Central Asia
Western North America.

Presentation Type: Oral Paper
Session: 28, Bryology and Lichenology (ABLS) II
Location: Sundance 1/Omni Hotel
Date: Tuesday, June 27th, 2017
Time: 3:45 PM
Number: 28009
Abstract ID:214
Candidate for Awards:None