Ecological Archives E094-168-A4

Chantal M. Huijbers, Ivan Nagelkerken, Adolphe O. Debrot, Eelke Jongejans. 2013. Geographic coupling of juvenile and adult habitat shapes spatial population dynamics of a coral reef fish. Ecology 94:1859–1870. http://dx.doi.org/10.1890/11-1759.1

Appendix D. Optimization of the size-dependent dispersal model, resulting in a median dispersal distance of 20–25 km/yr for larger (>45 cm) fish, and 2–3 km/yr for smaller (<20 cm) fish.

Because in the model age is used instead of size, size was calculated using the von Bertalanffy equation:

size = 50.25*(1-exp(-.139*(age-2+.955)))

FigD1

We assume that dispersal parameter λ is a linear function of size: λ = b0 + size × b1

and then optimize b0 and b1 for the model to best fit (1) the observed population sizes and (2) the observed size structures.

Result:

fitted to observed population sizes (R² = 59.9%)

fitted to observed size structures (R² = 49.5%)

The resulting λ-functions can be translated into median dispersal distances:

 

FigD2

And the same median dispersal distances plotted against age:

FigD3


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