Sarah Wells (Past student) (PhD)
Position: PhD Candidate

Phone: 0064 (0)9 4140800 ext: 41520

BSc(Hon) University of Southampton

Preserving Biodiversity Fund, Landcare Research (2009-2012), NZ,000 p.a.
JS Watson Grant, Forest and Bird Protection Society of New Zealand (2012, 2009), NZ,000
Auckland Council research grant (2009, 2010, 2011), NZ,000
Hutton Fund, Royal Society of New Zealand (2009), NZ,000
Commonwealth PhD scholarship (2009-2013), NZ,000 p.a. for 3.5 years
Massey University Doctoral scholarship

Supervisors / Supervisions:
Dr Weihong Ji
Dr Jim Dale
Dr Dianne Gleeson, Landcare Research, New Zealand, and University of Canberra, Australia

About Me

My research focuses two aspects: mating systems and sexual selection; and population genetics of tui, Prosthemadera novaeseelandiae. The tui is an endemic New Zealand honeyeater of the Meliphagidae family (Passeridae), but despite its iconic status in New Zealand and its role as an important pollinator of New Zealand forests, very few of its basic life history parameters are known.

With the advent of molecular parentage techniques, many socially monogamous birds have now been proven to be promiscuous. Such extra-pair mating strategies are typically viewed as life history traits that have evolved in order to maximise fitness. Despite being socially monogamous, tui also exhibit extreme sexual size dimorphism in both body size-a trait commonly associated with polygamous mating systems-and in a rare ornamental throat feather plume possessed by both sexes. My study combines behavioural observations and microsatellite data to produce the first detailed investigation of tui mating systems in which we determine the rate of extra-pair paternity present in tui.  We investigate phenotypic and genotypic correlates to male within-pair and extra-pair success in order to gain insight into the factors influencing female choice, and investigate whether direct or indirect benefits are of primary importance to female fitness. Finally we relate our findings to the current theories of sexual selection.

Secondly, my project uses microsatellites and several mitochondrial gene regions to elucidate the evolutionary history of tui populations throughout New Zealand. I am particularly interested in the role of islands in divergent evolution. Islands play an important role in speciation and, accordingly, the majority of endemic species occur on islands. However, the traditional view of strict biogeographic separation with no gene flow occurring during species formation has been challenged, and divergent evolution is now also thought to occur in the face of ongoing gene flow. New Zealand provides an excellent model as, as well as being an island itself in the broadest sense, it possesses a combination of remote offshore islands exhibiting extreme isolation, and near-shore islands with presumably significant gene flow with mainland populations.

My research aims to answer the following questions: 1) how has a species of honeyeater from a predominantly tropical family of birds managed to diversify throughout an extensive latitudinal range from the subtropics through to the sub-Antarctic and colonise the extremely remote Kermadec, Chatham, and Auckland Islands? 2) How genetically differentiated are these populations, and is there ongoing gene flow? Particularly, is the sub-species status of the Chatham Island tui, P.n. chathamensis, genetically supported? 3) Do tui follow the expected trend of geographic isolation during the last glacial maximum with subsequent demographic expansion out of ice-age refugia? 4) Has habitat fragmentation on the mainland influenced population structure, or is it more characterised by isolation-by-distance effects?