Abstract Detail


Nicolas, Antoine [1], Diallo, Fatimatou [2], Khasroo, Zemima [2], Obinelo, Adaeze [2], Plunkett, Gregory M.  [3].

Phylogenetics and Biogeography of Worldwide Hydrocotyle (Araliaceae).

Hydrocotyle is a genus of c. 200 species of herbaceous annuals and perennials that reproduce both sexually and clonally. The genus has a very rich taxonomic history in the order Apiales, particularly in relationship to its placement among the herbaceous-temperate Apiaceae and the mostly woody-tropical Araliaceae. Currently placed in Araliaceae, Hydrocotyle is the third largest genus in the family, and has a worldwide distribution with highest diversity in Australia and South America. Despite its taxonomic and ecological importance, no geographically comprehensive molecular studies have been conducted on the genus. So, this research represents a first molecular study that aims at defining the major clades of the genus, estimate phylogenetic relationships among and within these clades, and reconstruct the biogeographic history of Hydrocotyle. We sampled 175 ingroup specimens and sequenced regions from nuclear (ITS) and plastid (rpl32 trnL intergenic spacer and trnD-trnY-trnE-trnT region) genomes. We also sequenced whole plastomes for a subset of 30 species representing the major clades in the genus. Phylogenetic reconstruction showed multiple early-diverging, smaller clades that include mostly Australian endemics, suggesting an Australian origin for the genus. The rest of the species were included in two large clades, one comprises the Asia-Oceania species and the other includes the Pan American species. The Asia-Oceania clade includes multiple subclades with Australian links, indicating multiple dispersals between Australia and Asia/Pacific/New Zealand regions. The New Zealand species appear in three distinct subclades, one of which includes four Patagonian species, suggesting dispersal from New Zealand into southern South America, most likely through subantarctic island stepping stones. The Pan-American clade includes c. 100 species that exhibit the greatest variability in leaf morphology, which includes multiple independent events of peltate leaf formation. A most likely path of distribution is dispersal from Asia/Europe into North America and then Central America, followed by dispersals into the Caribbean and South America. Within the Pan-American clade, the Andean subclade makes the youngest major subclade of Hydrocotyle and shows a high diversification rate but very low genetic diversity, indicating rapid radiation in mid- and high-elevation Andean habitats.

1 - Manhattan College, Biology, Leo Building - Room 317D, 4513 Manhattan College Parkway, Riverdale, NY, 10471, United States
2 - Manhattan College, Biology
3 - New York Botanical Garden, Cullman Program For Molecular Systematics, 2900 Southern Blvd., Bronx, NY, 10458, United States


Presentation Type: Poster
Session: P, Systematics Posters
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 5:00 PM Time and date to be determined
Number: PSY020
Abstract ID:704
Candidate for Awards:None

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