A next-generation phylogenetics approach to explore the immense diversity of Australian thynnine wasps

Thomas Semple

Thynnine wasps (Tiphiidae: Thynninae) are a species-rich group of insects in Australia, with 474 species in 44 genera currently listed on the Australian Faunal Directory, and estimates of at least 1000 additional species known, but not yet described.

They display extreme sexual dimorphism, whereby males are winged and larger than the wingless females. Females spend the majority of their lives underground, where they seek out, paralyse and lay their eggs on scarabaeid beetle larvae. When females emerge from their subterranean homes they “call” to available males with pheromones, who then briefly alight to pick them up, before coupling their genitalia and mating mid-air.

Thynnine wasps are obligate pollinators of over 150 species of sexually-deceptive orchids in Australia. Many of these orchids are listed as threatened under the Environment Protection and Biodiversity Conservation Act (1999), such as the critically-endangered Caladenia procera, which is pollinated by the thynnine Zaspilothynnus nigripes.

In order to appropriately manage the conservation of these endangered orchids, we must gain a better understanding of the systematics of their pollinators. Griffiths et al. (2011) uncovered a significant amount of cryptic diversity within the thynnine genus Neozeleboria, and pollinator specificity is known to be high in sexually-deceptive orchids. As such, it is critical that we are able to reliably identify pollinators such as thynnines, so that the correct pollinator can be monitored or reintroduced along with orchid conservation programs.

Over a century ago, Turner (1907) published a revision of the subfamily (as what was then the family Thynnidae), which included just eight genera. There are now at least 44 described genera, and roughly the same number again, yet to be described. There is currently no comprehensive phylogeny or key to genera, meaning that accurate identification of specimens is completely reliant on one expert in Australia – Dr Graham Brown. A comprehensive phylogeny and systematic revision is long overdue for the group, and is an essential and complimentary step for progressing research on the ecology, evolution and behaviour of these unique Australian wasps.

The goal of this ignition project is to use next-generation sequencing (NGS) to assemble a phylogenetic backbone for the Thynninae, while testing the efficacy of a hymenoptera-specific sequence-capture kit. This is a commercially available bait set, designed by Faircloth et al. (2015) to target ~1500 ultraconserved elements (UCEs) across all Hymenoptera (wasps, bees, ants and sawflies). UCEs show great promise for phylogenetics, as the ultraconserved core regions can be aligned across whole families or orders, and the flanking regions can have enough variability to resolve species- or even population-level relationships.

Our initial sampling will include 96 individuals from across the whole subfamily, and will be informed by our close collaboration with Dr Brown. Specimens will come from recent collections made by the Peakall lab, as well as ethanol- and dry-preserved specimens in the Australian National Insect Collection (ANIC). This is an excellent opportunity to make use of this extensive collection, while forming a new collaboration between ANU and CSIRO research groups. It also presents a timely opportunity to make use of the new ancient-DNA laboratory at the Ecogenomics and Bioinformatics facility at ANU.

This collaboration combines a strong background in the behaviour, chemical ecology and systematics of thynnines from the Peakall lab (including the expert taxonomist Dr Brown), with the molecular systematics and collection genomics background of Dr Andreas Zwick. Dr Zwick’s expertise will be of particular benefit during the NGS design stage and subsequent phylogenetic analyses. Anticipated outcomes include at least one peer-reviewed publication and presentations by T. Semple at national and international conferences. 

 

Updated:  20 September 2017/Responsible Officer:  Director/Page Contact:  Coordinator