Abstract Detail

Systematics Section/ASPT

Nicolas, Antoine [1], Plunkett, Gregory [2].

Phylogeny of Asteriscium (Apiaceae, Azorelloideae) and Related Genera: Links to Australia and the Lomas of Chile and Peru.

The Asteriscium clade is one of three major clades in Apiaceae subfamily Azorelloideae (the other two being the Azorella and Bowlesia clades). The clade comprises c. 32 species in six genera, five of which (Asteriscium, Pozoa, Gymnophyton, Eremocharis, and Domeykoa) are limited mostly to arid habitats of Argentina, Chile, and Peru, while the sixth (Oschatzia) is found only in alpine and subalpine habitats of Australia. The group is most diverse in the coastal and upper lomas formations of the Atacama and Peruvian deserts, where four of the six genera are represented. These specialized hill formations support an entirely fog-dependent flora marked by very high levels of endemism, including many threatened species. Current generic circumscriptions in the group are based on fruit characters (fruit shape, compression, and presence of wings), but parsimony and likelihood analyses of sequence data from five nuclear regions and ten plastid regions provide evidence for the non-monophyly of four of the six genera. Three main lineages are apparent in this clade, one comprising Asteriscium, Gymnophyton, and Pozoa, a second with the interdigitated species of Eremocharis and Domeykoa, and a third with only the Australian genus Oschatzia. The placements of Pozoa and Oschatzia (both of which lack winged fruits) varies between plastid and nuclear phylogenies. Divergence estimates and biogeographic reconstruction analyses provide estimates that the species of the Asteriscium clade shared a common ancestor in South America dating to a median minimum age in the Early Eocene. Dispersal to Australia, where two species of Oschatzia are extant (one endemic to Tasmania and the other to the Australian Alps), most likely occurred via an Antarctic pathway during the Late Eocene-Early Oligocene. Independent dispersal events into the lomas took place in different clades, with the time of divergence between the Atacama and Peruvian desert clades estimated in the Late Miocene. In the Peruvian desert, the Pleistocene appears to be a time of high speciation (Domeykoa and Eremocharis). These speciation events very likely followed an island model, with the isolated lomas representing “islands of life” in the hyperarid desert.

Broader Impacts:

1 - New York Botanical Garden, Institute of Systematic Botany, 2900 Southern Blvd., Bronx, NY, 10458-5126, USA
2 - New York Botanical Garden, Cullman Program For Molecular Systematics, 2900 Southern Blvd., Bronx, NY, 10458-5126, USA

Keywords:
Apiaceae
South America
Atacama
Peruvian Desert
Australia
Azorelloideae.

Presentation Type: Oral Paper:Papers for Sections
Session: 33
Location: Rosedown/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 3:45 PM
Number: 33009
Abstract ID:819
Candidate for Awards:None