Abstract Detail

Biogeography

Potter, Benjamin [1].

Estimating the colonisation history and endemicity depth of the New Zealand tree flora.

The extant flora of New Zealand contains 271 species of endemic forest trees, spread across a broad spectrum of plant diversity (147 asterids, 83 rosids, 20 conifers, 10 magnoliids, 6 ferns, and 5 monocots). Here, we set out to characterise the colonisation history and temporal depth of this endemicity. Bayesian relaxed molecular clocks were used to date the NZ vs. overseas floristic disjunctions, and place the NZ immigrations along an evolutionary timeline. The primary aims were: (1) to contrast the historical arrivals with significant geological and climatological events, (2) build a time-calibrated framework for tree diversification and phylogeography research, and (3) assemble a database useful for community assembly analyses, focused on the role of deep-time priority effects in shaping plant community structure. Towards this an assessment of the molecular dating literature was carried out (focusing exclusively on studies employing relaxed clock models in BEAST), resulting in immigration ages for 37 tree genera. For the remaining 48 genera that were undated in the literature, molecular dating analyses were conducted using a combination of publically available and newly generated DNA sequence data. Preliminary results suggest that although the Zealandia continental fragment has been geographically isolated for ca. 80 million years, over 85% of the tree colonisations can be attributed to dispersal events in the Early Miocene or later (mean ages). The southern conifers (Araucariales) were clear outliers, with some of their NZ-overseas disjunctions dating back to the mid Cretaceous – but as this clade has been heavily influenced by extinction these colonisation ages remain difficult to substantiate. Broadly, these dates are more in line with a ‘fly-paper of the South Pacific’ hypothesis for the NZ tree flora, rather than supporting a continuous post-Gondwanan presence.

1 - University of Auckland, School of Biological Sciences, 3a Symonds Street, Auckland, 1010, NZ

Keywords:
Austral biogeography
long-distance dispersal
historical biogeography
New Zealand
Molecular dating
phylogenetics.

Presentation Type: Oral Paper
Session: 43, Biogeography III
Location: 205/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 2:45 PM
Number: 43006
Abstract ID:920
Candidate for Awards:None