Dissecting the drivers of population cycles: Interactions between parasites and mountain hare demography
Authored by Sunny E Townsend, Scott Newey, Simon J Thirgood, Daniel T Haydon
Date Published: 2011
DOI: 10.1016/j.ecolmodel.2010.08.033
Sponsors:
No sponsors listed
Platforms:
MATLAB
Model Documentation:
Other Narrative
Flow charts
Mathematical description
Model Code URLs:
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Abstract
There is a growing awareness that cyclic population dynamics in
vertebrate species are driven by a complex set of interactions rather
than a single causal factor. While theory suggests that direct
host-parasite interactions may destabilise population dynamics, the
interaction between host and parasite may also influence population
dynamics through indirect effects that result in delayed responses to
either density or to life-history traits. Using empirical data on
mountain hares (Lepus timidus) infected with a nematode parasite
(Trichostrongylus retortaeformis), we developed an individual-based
model (IBM) that incorporated direct effects and delayed life-history
effects (DLHEs) of a macroparasite, alternative transmission mechanisms
and seasonality in host population dynamics. The full model describes
mean characteristics of observed mountain hare time series and parasite
abundance, but by systematically removing model structure we dissect out
dynamic influences of DLHEs. The DLHEs were weakly destabilising, increasing the propensity for cyclic dynamics and suggesting DLHEs could
be important processes in host-parasite systems. Further, by modifying
model structure we identify a strong influence of parasite transmission
mechanism on host population stability, and discuss the implications for
parasite aggregation mechanisms, host movement and natural geographical
variation in host population dynamics. The effect of T. retortaeformis
on mountain hares likely forms part of a complex set of interactions
that lead to population cycles. (C) 2010 Elsevier B.V. All rights
reserved.
Tags
Dynamics
Aggregation
stability
Life-history
Reproduction
Abundance
Red grouse
Maternal effect hypothesis
North-east scotland
Lepus-timidus