<B>Daniel T. Haydon</B> Daniel T. Haydon
B.Sc., University of Southampton, 1986
Ph.D., University of Texas at Austin,1992

I am principally interested in understanding mechanisms of population persistence and causes of population fluctuation. I think that these issues may be profitably studied from the interface of landscape ecology and population dynamics. I believe that ecology was ill-served by the early pre-occupation with the stability of point equilibria in studying the phenomena of population persistence. Modelling in the biological sciences is done a great disservice by the expedient application of tractable but biologically irrelevant analyses. Populations exist within a variously dimensional space and in most cases move around within it. Inclusion of spatial extent into models of population processes permits a variety of non-equilibrium persistence strategies that are not permitted in non-spatial models of population dynamics. However, most of these non-equilibrium persistence strategies require that individuals be heterogeneously distributed over this space, and co-vary asynchronously with time across space. Mechanisms by which these asynchronies are perpetuated are not well understood. Mathematically it is thought that the presence of spatial asynchrony within non-driven but weakly connected spatial domains tends to be ephemeral. Possible mechanisms that resist this natural tendency to synchrony are: fixed spatial heterogeneity, locally acting stochastic fluctuations, inherent aspects of the systems dynamics, interspecific interference from parasites, predators and competitors, or geometrical characteristics of the spatial domain. These last two possibilities are particularly interesting. The geometry and quality of habitat mosaics resulting from the natural distribution of usable habitat or progressive habitat destruction and its consequent fragmentation are likely to be important determinants of the nature of population dynamics. The persistence of multiple interacting populations over a (variously) fragmented landscape is likely to be a function of their differential ability to colonize and persist within a patch. Specifically I am interested in the role of landscape geometry in determing large scale species persistence and how this role might vary with the nature of a population's trophic interactions and with a species' different life history characteristics. The purpose of acquiring such an understanding might be of benefit in the management of both pestilent/outbreak and endangered species.

I am pursuing these questions at a theoretical level, using both mathematical models and computer simulation. The existence of asynchronous population dynamics implies the presence of spatial pattern, the perceived nature and flux of which is likely to depend on the scale at which it is viewed. Any perception of population fluctuation is scale dependent, I am interested in how this scale dependency interacts with our ability to correctly elucidate population process from pattern. These questions emerge naturally from spatially explicit population models.

Some recent work at Oxford done on periodic epidemics resulting from seasonal forcing of population dynamics has served to highlight the extent to which the impact of seasonality is ignored in population dynamic theory. Theoreticians seem to shy away from many of the externally acting perturbing forces influencing population dynamics - often obvious to empirical biologists working with populations in seasonal environments - preferring the mathematically tidier explanations for the presence of periodic or aperiodic dynamics provided by limit cycles and chaos theory. I am interested in developing and using detailed computer models of specific populations and modern techniques in sensitivity analysis to investigate the role of small shifts in the phase and amplitude of seasonal forcing on the resulting fluctuations in population dynamics.

Evidence is mounting from developments in epidemiological theory that the behaviour of simple models of population processes is particularly sensitive to the assumption that rate processes may be adequately described deterministically. This problem may well be relevant to many more numerous population interactions, and it is highly likely to be critically important to the dynamics of rare species and those that exist at low densities. I am particularly interested in examining these theoretical ideas within the context of a specific rare and/or endangered species system.

Theoretical modelling conducted in the total absence of empirical interaction is likely to be of at best only heuristic value (and even then only to those who find such material accessible). Most of my post-doctoral research at Oxford has required bringing theoretical ideas to empiricists and working with these ideas in close collaboration with them. I plan to continue to conduct research in the same way at the University of British Columbia.

<B>Publications:</B> Publications:

Haydon, D., R. R. Radtkey, and E. R. Pianka. 1993. Experimental Biogeography: Interactions between stochastic, historical, and ecological processes in a model archipelago. Chapter 11 (pp. 117-130) in R. E. Ricklefs and D. Schluter (eds.) Species Diversity in Ecological Communities: Historical and Geographical Perspectives. University of Chicago Press.

Haydon, D., B. I. Crother, and E. R. Pianka. 1994. New directions in biogeography? Trends in Ecology and Evolution 9: 403-406.

Haydon, D. 1994. Pivotal assumptions determining the relationship between stability and complexity: an analytical synthesis of the stability-complexity debate. American Naturalist 144: 14-29.

Woolhouse, M.E.J., Haydon, D.T., Pearson, A., and Kitching, R.P. (1996). Failure of vaccination to prevent outbreaks of foot and mouth disease. Epidemiology and Infection 116:363-371

Haydon, D.T., Woolhouse, M.E.J. and Kitching, R. P. (1997). An analysis of foot and mouth disease epidemics in the UK. IMA Journal of Mathematical Applications in Medicine and Biology 14:1-9

Woolhouse, M.E.J., Haydon, D.T., and D.A.P Bundy. (1997). The design of veterinary vaccination programmes. The Veterinary Journal 153:41-47

Adzhar, A., Gough, R.E., Haydon, D.T., Shaw, K., Britton, P., and Cavanagh, D. Molecular analysis of the 793/B serotype of infectious bronchitis virus in Great Britain. Accepted for publication in Avian Pathology.

Haydon, D.T. and Steen, H. The effects of large and small scale random events on the synchrony of metapopulation dynamics: a theoretical analysis. Accepted for publication in Proceedings: Biological Sciences (The Royal Society, UK).

Haydon, D.T., Lea, S., Fry, E., Knowles, N., Samuel, A.R., Stuart, D., and Woolhouse, M.E.J. Characterizing Sequence Variation in the VP1 Capsid Proteins of Foot and Mouth Disease Virus (Serotype O) with Respect to Virion Structure. Submitted to Journal of Molecular Evolution.

Judson, O.J., and Haydon, D.T. The Genetic Code: what is it good for. Submitted to Nature.

Email address: haydon@zoology.ubc.ca