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© Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington MSc Student Supervisors : Dr Stephen Hartley, Dr Marcus Frean Victoria.

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Presentation on theme: "© Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington MSc Student Supervisors : Dr Stephen Hartley, Dr Marcus Frean Victoria."— Presentation transcript:

1 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington MSc Student Supervisors : Dr Stephen Hartley, Dr Marcus Frean Victoria University, Wellington Jim Barritt Spatially explicit simulation of individual foraging behaviour across patchy resources

2 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Introduction Spatial ecology - Animal Movement - Resource distribution (patches) Study species - Cabbage white butterfly (Pieris rapae) - Diamondback moth (Plutella xylostella) - Parasitoid wasps (Cotesia glomerata)

3 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Study species Herbivorous caterpillars Host plants are cabbages (Brassicaceae family) © Smithsonian Institute Cabbage White (Pieris rapae)Diamondback (Plutella xylostella)

4 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Parasitoids Cotesia glomerata Parasatised (brown) Pieris rapae pupa Cotesia glomerata emerge from Pieris larvae. © © Marc Hasenbank Parasitoid eggs.

5 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Foraging for an oviposition site

6 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Foraging for an oviposition site Which cabbage ?

7 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Hypotheses Define a relationship between - Number of eggs per plant - Density of plants in a patch Three alternatives….

8 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington 1 Ideal Free Distribution

9 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington 2 Resource concentration DRAW A PICTURE HERE Resource concentration hypothesis - Root (1973) Resource dilution hypothesis - Grez & Gonzalez (1995) Ideal free distribution - Fretwell & Lucas (1970)

10 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington 3 Resource Dilution Insert a picture here!!!

11 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Hypotheses Correlation between plant density and eggs per plant BUT … Density and Isolation depend on scale … Resource concentration Resource dilutionIdeal free distribution

12 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Density and Isolation are scale dependant 10 m 1 plant 20 plants, density = 0.2 plants / m 2

13 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Density and Isolation are scale dependant 30 m 1 plant 54 plants, density = 0.06 plants / m 2

14 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Density and Isolation are scale dependant 432 plants, density = plants / m 2 90 m 1 plant Figures incorporating concept from S.Hartley

15 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Project Aims Create a simulation environment - Baseline from published simulation methods - Introduce biologically realistic mechanisms - Integrated statistical analysis, e.g. R ( ) Investigate resource distribution hypotheses at different scales - How does the scale and pattern of movement relate to egg distributions at different scales ? - Move length, directionality, dispersal ability - Can we observe different effects at different scales ? Explore multi-species dynamics (Parasitoids)

16 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Existing Simulations Observational (Jones 1977) - Based on field observations - Maximum likelihood estimation for parameters Correlated Random walk (Cain 1985) - Importance of mortality Perceptual (Olden et al 2004) - E.g. Visual or Olfactory - Perceptual range

17 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Observational MOVE (directionality) LAY (plant species, plant age) STOP (plant species, plant age, fecundity of butterfly) CONT

18 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Correlated Random Walk Start Plant Radius of detection Figure from Cain (1985)

19 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Perceptual Olfactory / visual stimuli Direction influenced by stimuli Stimulus strength - Caterpillars munching Wind Start

20 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Methods Simulation framework (Java) - Provide a spatially and temporally explicit landscape - Continuous space - Grid-based view - Agents interact with landscape Common output allows different simulation methods to be compared

21 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington First Steps Random walk into a pit - Based on experiments using pitfall traps

22 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Summary Spatially explicit simulation Individual foraging behavior - Biological realism (olfactory and visual) - Effects of scale Resource concentration / dilution hypotheses Predator (Parasitoid) / Prey interactions Jim Barritt

23 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Acknowledgements Thanks to - Dr Stephen Hartley - Dr Marcus Frean - Marc Hasenbank - Victoria University Bug Group © Smithsonian Institute ©

24 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington References Aldrich, J. (1997). R.A. Fisher and the making of maximum likelihood Statistical Science 12, pp Bukovinszky, T., R. P. J. Potting, Y. Clough, J. C. van Lenteren, and L. E. M. Vet. (2005). The role of pre- and post-alighting detection mechanisms in the responses to patch size by specialist herbivores. Oikos 109, pp Byers, J. A. (2001). Correlated random walk equations of animal dispersal resolved by simulation. Ecology 82, pp Cain, M. L. (1985). Random Search by Herbivorous Insects: A Simulation Model. Ecology 66, pp Finch, S., and R. H. Collier. (2000). Host-plant selection by insects - a theory based on 'appropriate/inappropriate landings' by pest insects of cruciferous plants. Entomologia Experimentalis Et Applicata 96, pp Fretwell, S. D., and H. L. Lucas. (1970). On territorial behaviour and other factors influencing habitat distribution in birds. Acta Biotheoretica 19, pp Grez, A. A., and R. H. Gonzalez. (1995). Resource Concentration Hypothesis - Effect of Host-Plant Patch Size on Density of Herbivorous Insects. Oecologia 103, pp Holmgren, N. M. A., and W. M. WGetz. (2000). Evolution of host plant selection in insect under perceptual constraints: A simulation study. Evolutionary Ecology Research 2, pp Jones, R. E. (1977). Movement Patterns and Egg Distribution in Cabbage Butterflies. The Journal of Animal Ecology 46, pp Olden, J. D., R. L. Schooley, J. B. Monroe, and N. L. Poff. ( 2004). Context-dependent perceptual ranges and their relevance to animal movements in landscapes. Journal of Animal Ecology 73, pp Otway, S. J., A. Hector, and J. H. Lawton. (2005). Resource dilution effects on specialist insect herbivores in a grassland biodiversity experiment. Journal of Animal Ecology 74, pp Root, R. B. (1973). Organization of a Plant-Arthropod Association in Simple and Diverse Habitats: The Fauna of Collards (Brassica Oleracea). Ecological Monographs 43, pp Tilman, D., and P. M. Kareiva. (1997). Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Monographs In Population Biology 30

25 © Jim Barritt 2005School of Biological Sciences, Victoria University, Wellington Questions ? Spatially explicit simulation Individual foraging behavior - Biological realism (olfactory and visual) - Effects of scale Resource concentration / dilution hypotheses Predator (Parasitoid) / Prey interactions Jim Barritt


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