Western Melanesian Herpetofauna Diversity
Research Approach & Strategy
Objectives
Our research goals are to: ​
-
Identify which of western Melanesia’s endemic clades have ancient insular origins in the South Pacific instead of modern New Guinea and where and when those taxa arose.
-
Identify whether later evolutionary success of those taxa has varied with origin times or locations.
-
Identify those geological events seminal in generating endemic biodiversity at those times and source areas using updated models of the region’s geological history.
-
Cross-validate how closely divergence and colonisation dates derived from our molecular analyses match accretion and emergence dates obtained from the geological record.
-
Determine whether there is a predictable time lag between geological accretion events (which are submarine) and biotic colonisation events (which are subaerial).
-
Establish whether taxa endemic to the northern accreted terranes diverged prior to or subsequent to their docking with New Guinea.
-
Tighten date estimates in each tree by linking phylogenetic divergences of taxa endemic across the Milne Bay islands (the southeastern most portion of the EPCT) to closely dated geological divergences during the recent opening of the Woodlark Rift (6–2 Mya).
Taxonomic Groups
We will use multiple reptile and amphibian clades to identify and date source areas within western Melanesia.
We choose these taxa because:
-
They all exhibit high diversity within western Melanesia
-
Their intermediate levels of mobility provide sufficient dispersal ability to colonise insular areas, but not enough that geographic patterns will often be overwhelmed by repeated colonisation or back dispersal
-
We have extensive collections of tissues and specimens to use for inferring evolutionary relationships among regions
We will supplement published trees with additional taxa of ours and create new trees for previously unstudied clades. We will assess robustness of date estimations for each of these data sets and strategically add further taxa and/or genes as needed to improve estimated dates, topological relationships, and historic biogeographic analyses.
Data Generation
We will amass our datasets by:
-
Producing phylogenetic trees from previously unstudied clades
-
Supplementing previously published trees with additional taxa of ours
-
Re-analysing previously published sequence data with our specific questions in mind (i.e. molecular dating and biogeographic reconstructions)
​
We will generate novel data from:
-
Tissue samples amassed by co-principle investigator Fred Kraus during his prior expeditionary work in the region
-
Extensive tissues to be collected during a team expedition and from fieldwork by project partner Owen Paiva
-
Samples available from museums or other researchers active in the region, including more project partners
Research Methods
We will extract DNA using Qiagen DNeasy Blood and Tissue Kits for recent tissue samples or an ancient DNA protocol for historic museum samples, for which we will use high-throughput sequencing methods.
​
We will generate sequences from ultraconserved elements (UCEs) to produce trees and apply fossil calibrations for dating analyses. UCEs are advantageous over traditional methods because the volume of data generated allows for construction of more robust phylogenies, and the method allows historical museum specimens to be included in analyses.
​
We will supplement already-published molecular datasets by generating additional sequences for all herpetological taxa currently available to us (or to be newly collected during the study). We will complete dating and biogeographic analyses for previously published studies that lack divergence date estimates or biogeographic analyses and for which we do not have additional taxa.