NERC FUNDED PhD STUDENTSHIP AVAILABLE NOW
(Deadline for applications: February 24th 2008)
Survival through the Arctic winter:
nematodes influence fitness in
Supervisors: Dr Ken Wilson; (
Start date: January 2009
Background and Rationale
Regulation of animal populations by their parasites was demonstrated
using mathematical models nearly 30 years ago (Anderson & May 1978, May
& Anderson 1978). Theoretical studies examining the dynamics of
host-parasite interactions have since flourished (Dobson & Grenfell 1995).
However, whilst many empirical studies have quantified the negative impact of
parasites on host survival and fecundity (Gulland 1995), few have come close to
demonstrating that macroparasites can regulate wildlife populations, mainly due
to logistical difficulties (Hudson et al., 2002). There are two exceptions
(Wilson 2002): 1) the role of caecal worms (Trichostrongyle
tenuis) in red grouse dynamics (Hudson et
al 1992, 1998), and 2) the role of abomasal nematode (Ostertagia gruehneri) in
Experiments using anthelmintics that remove O. gruehneri have shown that parasite-mediated reduction in fecundity increases as the intensity of the parasite infection increases, which, in turn is related to the host population density two years earlier (Albon et al. 2002 and featured in Begon, Townsend & Harper 2006 Ecology: From Individuals to Ecosystems, 373-376). Recent developments in anti-parasite drug delivery now permit an experimental manipulation of the impact of the winter-transmitted M. marshalli on the reindeer hosts. M. marshalli, is an ostertagid like parasite of animals in cold deserts and can have negative impacts on its hosts (Morgan et al., 2004).
This studentship will test the hypothesis that, since M. marshalli infects reindeer over winter when they are starving, it depresses host performance, reduces survival and has a role in regulating reindeer population dynamics.
Methodology and Approach
area and animals: Located on Nordenskiold, Spitsbergen,
Experimental Design: When reindeer are captured, anti-helminth drugs can be administered to remove their parasite burden at specific times of year. This will allow us to test a number of specific predictions about the interaction between the reindeer and its parasites:
1) After 4 months (in February), reindeer treated with the delayed-release bolus will have a lower abundance of parasites than untreated controls, and these parasites will be largely M. marshalli.
2) By April, the proportional decline in body weight and body fat will be lower in the treatment groups than in the untreated controls, with those receiving a second dosing in February losing least condition.
3) Differences in relative change in body condition between treated animals and untreated controls will increase with winter severity (total precipitation Oct-Apr) and host density.
4) The probability of survival to the following winter will be highest in treated animals, especially those receiving a second dosing.
The student will receive
an induction into theoretical population ecology, and specifically
host-parasite interactions, through
The CASE partner (Macaulay Institute) will provide practical training in animal capture-mark-recapture, field experimentation and monitoring, as well as advanced statistics facilitated by Biomathematics and Statistics Scotland.
student will learn basic parasitological laboratory methods, as well as
molecular techniques at the
student will take part in field studies on Svalbard during several weeks each
year, where they will be associated with the University Centre in
You mat apply online at https://www.pgapps.lancs.ac.uk/
University application forms and guidance notes are available online at:
Email enquiries to: firstname.lastname@example.org
Additional information about PhDs within the Lancaster Environment Centre can be found at: http://www.lec.lancs.ac.uk/postgraduate/phd/
Interviews will be held between 10th and 14th March 2008
Albon, S. D., Stien, A., Irvine, R.J., Langvatn, R., Ropstad, E. & Halvorsen, O. (2002). The role of parasites in the regulation of a reindeer population. Proc. Royal Society B. 269, 1625-1632.
Dobson, A. P. & Grenfell, B. T.
(1995). Introduction. pp. 1-19. In Ecology
of Infectious Diseases in Natural Populations (ed. Grenfell, B. T. &
Dobson, A. P.),
Gulland, F.M.D. (1995). The impact of infectious diseases on wild animal populations ‑ a review. pp 20‑51 in Ecology of Infectious Diseases in Natural Populations (ed B.T. Grenfell & A.P. Dobson) Cambridge University Press.
Hudson P.J., Dobson, A.P. & Newborn, D (1998). Prevention of population cycles by parasite removal. Science, 282, 2256-2258.
R.J., Stien, A., Halvorsen, O., Langvatn, R. & Albon, S.D. (2000). Life-hisory strategies
and population dynamics of abomasal nematodes in
May R.M. & Anderson R.M. (1978). Regulation and stability of host-parasite population interactions. II. Destabilising processes. J. Anim. Ecol. 47, 249-267.
Morgan, E. R., Milner-Gulland, E. J., Torgerson, P. R. & Medley, G. F. (2004). Ruminating on complexity: macroparasites of wildlife and livestock. TREE 19, 181-188.
Stien, A., Irvine, R.J., Ropstad, E., Halvorsen, O., Langvatn, R. & Albon, S. D. (2002). The impact of gastrointestinal nematodes on wild reindeer: experimental and cross - sectional studies. J. Anim. Ecol. 71, 937-945.
Wilson, K. (2002). Ups and downs of wildlife population regulation by macroparasites. TREE, 17, 454.
(all photographs copyright Erik Ropstad)