Abstract Detail

Biogeography

Sharples, Mathew [1], Tripp, Erin [2].

Inferring the biogeographical history of the cosmopolitan Angiosperm genus Stellaria L.

The genus Stellaria L. (the “starworts”, Caryophyllaceae) is a diverse lineage (~100 spp.) with a cosmopolitan natural distribution spanning six continents. Given this extant diversity across such a wide spatial scale, we aimed to infer the biogeographical history of the starworts. We explicitly set out to test the hypotheses that: 1) Stellaria originated in the Greater Himalaya, which also represents its center of diversity, 2) the endemic diversity in Oceania derived from multiple ancestral long-distance dispersal events to yield the incredible morphological and species habitat diversity there, and 3) that migrations from Asia across Beringia can explain the diversity of Stellaria found in the New World. To test these hypotheses, we first reconstructed a best estimate phylogenetic history of Stellaria, including over 80% of species in the genus, using RADseq data; we furthermore inferred divergence timing of lineages using both a primary fossil calibration and secondary calibration approaches. We then compared ancestral area reconstruction models using BioGeoBEARS and found that the common ancestor of core Stellaria likely evolved in the late Tertiary somewhere between Maritime Asia and Eastern North America, suggesting that this genus represents a hitherto unrecognized element in the well-studied pattern of Tertiary flowering plant disjunctions between Eastern North America and Eastern Asia. These results also suggest amphi-Beringian Tertiary vicariance to explain the distribution of early-diverging New World taxa in Stellaria. Contrary to dogma on predicted correlations between high species diversity and centers of origins, our analyses suggest that high Stellaria diversity in Greater Himalaya can be explained largely through one relatively recent diversification event. Our results also demonstrate that the incredible diversity present in Oceania is likely likewise explained through a single ancestral long-distance dispersal event, potentially from Eurasia, with subsequent expansion and diversification in the region. We additionally find that both “paleo” and “neo” movements across Beringia from Asia can explain the breadth of diversity of Stellaria in the New World. Our study thus elucidates the biogeographical history of a cosmopolitan and diverse lineage of flowering plants, one for which we have near complete sampling of extant taxa. These results will be a useful future reference for comparative biogeographical work in Caryophyllaceae and other lineages.

1 - 745 College Ave., Boulder, CO, 80302, United States
2 - C105, Ramaley Hall, UCB350, Clare Small Building, Basement, Boulder, CO, 80309, United States

Keywords:
Biogeography
Stellaria
Caryophyllaceae
RADseq
BioGeoBEARS
center of diversity
Himalaya
Oceania
Beringia.

Presentation Type: Oral Paper
Session: 4, Biogeography
Location: 105/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 8:15 AM
Number: 4002
Abstract ID:175
Candidate for Awards:None