NERC FUNDED PhD STUDENTSHIP AVAILABLE NOW
(Deadline for applications: February 24th
2008)
Survival
through the Arctic winter:
How gastrointestinal
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
For
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
Study
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.
Research training
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.
The
student will learn basic parasitological laboratory methods, as well as
molecular techniques at the
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
Application procedure
Informal
enquiries can be made to Dr Ken Wilson (email: ken.wilson@lancaster.ac.uk) or
Prof Steve Albon (s.albon@macaulay.ac.uk).
You mat apply online at https://www.pgapps.lancs.ac.uk/
University application forms and
guidance notes are available online at:
http://www.lancs.ac.uk/users/admissions/postgrad/pgform1.htm
Email enquiries to: lec.pg@lancaster.ac.uk
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
References
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.
Irvine,
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)