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Coloured noise affecting single-species populations in a spatial setting

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Coloured noise affecting single-species populations in a spatial setting

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  1. Colourednoiseaffectingsingle-species populations in a spatial setting Frida Lögdberg

  2. Single-patch populations • Over compensatory: reddening of noise (increase in autocorrelation) willdecreaseextinction risk. • Under compensatory:reddening of noisewillincreaseextinction risk.

  3. Twomodels Model 1: Landscape implicit Model 2: Landscape explicit

  4. Model 1 • Discrete population process (Ricker): • Dispersal is a mass-actionmixing process:

  5. Environmentalnoise • 1/f noise in 2D: • Time, noisecolor • Space, synchrony

  6. Model 1 • Noiseaffecting K: • Noiseaffecting r (indirect):

  7. Model 1: Results • Over comp., noise in K: as the single-patch system. • Undercomp ., noise in K: hump-shapedresponse. • Over comp., noise in r: small hump-shapedresponse. • No interaction effectsbetweensynchrony and colour. Noise in K, over comp. Noise in K, under comp. Noise in r, over comp.

  8. Model 2 • Discrete population process (Ricker): • Dispersal isdistancedependent and follows a negative exponential distribution. • Environmentalnoise (colour and synchrony) as in Model 1.

  9. Model 2 Landscapes: generated with spectralmethod. Landscape characteristics: Continuity Contrast Continuity = 0 Continuity = 1 Continuity = 5 Contrast = 1 Contrast = 3 Contrast = 5

  10. Model 2: Results Pop. dynamics is over compen-satory. Noiseenters in K. Continuity = 0 Continuity = 1 Continuity = 5 Contrast = 1 Contrast = 3 Contrast = 5

  11. Model 2: Results Pop. dynamics is under compen-satory. Noiseenters in K. Continuity = 0 Continuity = 1 Continuity = 5 Contrast = 1 Contrast = 3 Contrast = 5

  12. Model 2: Results Pop. dynamics is over compen-satory. Noiseenters in r. Continuity = 0 Continuity = 1 Continuity = 5 Contrast = 1 Contrast = 3 Contrast = 5

  13. Conclusions • No complex interaction effectsbetweenany of landscape, synchronyand colour. • Aggregation versusrandom landscape affects the extinction risk quantitatively. Men ar du tydlig effekt/markerad effekt • Population dynamicsmatter, alsowhenincreasing the complexity by addingspace.

  14. Implications • To determineextinction risk onehave to consider: dynamics, colour, synchrony, continuity, contrast. • Besidesmean and varinace of resources. • On the other hand most of thesehave the same effectregardless of the others • If you want to improve the survival of the populationYou should: • Redder the noise or whiter the noise (be careful with dynamics) • Reducesynchrony • Increasecontrast • Reducecontinuity • (and of courseincrease man and reducevariance) • I f you have to choose: Which is the best to do? Depends on what system, what parameters value you have.