Abstract Detail

Pacific Biogeography

Potter, Benjamin [1], Newcomb, Richard [2], Drummond, Alexei [3], Lee, William [4].

Retracing the colonisation history of the endemic New Zealand grass flora (Poaceae).

Insular floras that contain high levels of endemism provide fascinating case studies of colonisation history. Assemblages of historically accumulated indigenous diversity (often including radiations of taxa), containing a variety of lineages with different immigration ages and richness values, offer unique insights into diversification. The grasses of New Zealand – a species-rich flora consisting of 161 endemics and 33 indigenous non-endemics – represent such a group. Native diversity is distributed across 12 of the 51 currently accepted Poaceae tribes, but taxa from two tribes comprise 84% of the species: Poeae (116 spp.) and Danthonieae (47 spp.). Here, we set out to characterise the NZ colonisation history of these grass taxa. Towards this molecular dating analyses were conducted using a combination of publicly available and newly generated DNA sequence data. Bayesian relaxed clocks were used to date the NZ vs. overseas floristic disjunctions, and place the NZ immigrations along an evolutionary timeline. Preliminary results suggest that the NZ grass flora is the product of ca. 32 colonisation events, with the majority of these occurring during the Late Miocene to Pliocene. Just three lineages were estimated to have older stem ages: Austroderia (mean age: 13 Ma), Chionochloa (24 Ma) and Ehrharta (38 Ma). These results are discussed with reference to the significant geological and climatological events that have impacted the Zealandia continental fragment over this time frame, and contrasted with a similar colonisation history that was recently constructed for NZ’s tree flora.

1 - University of Auckland, School of Biological Sciences, 3a Symonds Street, Auckland, 1010, NZ
2 - New Zealand Institute for Plant & Food Research Ltd, Auckland, New Zealand
3 - University of Auckland, Centre for Computational Evolution, Auckland, New Zealand
4 - Landcare Research, Dunedin, New Zealand

Keywords:
Biogeography
molecular dating
New Zealand
phylogeny
Poaceae.

Presentation Type: Colloquium Presentations
Session: C12, Pacific biogeography
Location: 103/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 1:45 PM
Number: C12001
Abstract ID:1213
Candidate for Awards:None