Alien ants: invaders of a tropical island food web in the Indian Ocean - NERC GW4+ DTP project

This project is one of a number that are in competition for funding from the NERC GW4+ DTP. The GW4+ DTP consists of the Great Western Four alliance of the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus six Research Organisation partners. The partnership aims to provide a broad training in earth and environmental sciences, designed to train tomorrow’s leaders in earth and environmental science. For further details about the programme, please see http://nercgw4plus.ac.uk/.

Background

Ants have pivotal roles in many ecosystems as predators, herbivores and seed dispersers. Alien ants are invading food webs and damaging ecosystems worldwide.

In the USA the Red Imported Fire ant, Solenopsis invicta, has caused severe ecological and economic damage.

On Christmas Island, Yellow Crazy ants, Anoplolepis gracilipes, are having devastating effects on keystone land crabs, radically altering the whole ecosystem.

Alien ant species most likely to dominate an ecosystem have a high intrinsic rate of increase, are highly polyphagous, attack other ant species, establish mutualistic relationships with herbivores and/or are major dispersers of invasive plants.

Nobody has previously analysed the complete diets of alien or native ants (plant and animal) in the field using Next Generation Sequencing (NGS). No one has used such data to analyse the complex effect on ecological communities of interactions between invasive and native ants, and other invertebrate/vertebrate species, using such an approach.

Project aims and methods

Round Island (RI) is a near-pristine volcanic Mauritian islet containing many species of endemic reptile and thriving seabird colonies. Ants comprise 78% of invertebrate abundance, dominated by highly-invasive Big-Headed ants, Pheidole megacephala. You will:

- analyse the roles of alien ant species within the food web
- determine the mechanisms by which ants threaten an island ecosystem.

We will analyse the full dietary range of alien and native ants, using next generating sequencing (NGS) to detect invertebrate, plant and vertebrate prey. We have already barcoded all the RI plant species allowing precise identification. Invertebrate prey will now be identified and their DNA barcoded. Rates of feeding on these food resources (determined using NGS) will be compared with relative availability (within quadrats) to determine prey choice and prey overlap between alien and native ant species.

An experimental manipulation, treating invasive ant nests with formicides, will be used to reveal the effects of removing invasive ants from the food web. Reptiles, that may limit ant numbers, will be screened for ant DNA.

The project will reveal fundamental processes affecting the ability of ants to modify island ecosystems and guide future management.

Candidate

The ideal candidate would enjoy the mix of lab and fieldwork. You should be interested in insects and ecology generally. Molecular ecology experience would be helpful but not essential. You should be prepared to work with a small group for extended periods on a semi-isolated tropical island with few amenities.

CASE award

This is a CASE award. Durrell Wildlife Conservation Trust (DWCT) will provide £7.0k towards consumables (£2.0k p.a. over 3.5 years). Extra expenses incurred by the student while working with the CASE partner (e.g. accommodation on the island, boat transport to/from the island, warden assistance on the island etc.) will be covered by DWCT and the project partners, the Mauritian Wildlife Foundation (contact Vikash Tatayah) as ‘in kind’ support.

Training

You will take full advantage of courses provided by the GW4 DTP (e.g. statistics, bioinformatics). Additional courses will be selected (depending upon student background) provided by the Doctoral Academy (eg courses on interacting with their supervisors, risk assessment, writing a PhD Thesis, writing grant proposals and diversity training).

Training related to the project will be provided by the supervisors and their research teams in Mauritius and UK. Additional training opportunities will be available through Durrell in Jersey and Bath. This will include hands-on training pertaining to field-based conservation management, molecular ecology techniques and food web analyses.

Previous PhD graduates have gone on to successful careers in, for example, the Centre for Ecology and Hydrology, academic positions in Universities, conservation positions (such as wardens within nature reserves), and the National Rivers Authority.