Description Usage Arguments Details Value Note Author(s) References See Also Examples

This function calculates the degree of overlap between the predictions of two models, using niche comparison metrics such as Schoener's D, Hellinger distance and Warren's I.

1 | ```
modOverlap(pred1, pred2, na.rm = TRUE)
``` |

`pred1` |
numeric vector of the predictions of a generalized linear model (values between 0 and 1). |

`pred2` |
numeric vector of the predictions of another generalized linear model; must be of the same length and in the same order as |

`na.rm` |
logical value indicating whether |

See Warren et al. (2008).

This function returns a list of 3 metrics:

`SchoenerD` |
Schoener's (1968) D statistic for niche overlap, varying between 0 (no overlap) and 1 (identical niches). |

`WarrenI` |
the I index of Warren et al. (2008), based on Hellinger distance (below) but re-formulated to also vary between 0 (no overlap) and 1 (identical niches). |

`HellingerDist` |
Hellinger distance (as in van der Vaart 1998, p. 211) between probability distributions, varying between 0 and 2. |

A function providing similar measures, `niche.overlap`

, is available in package phyloclim, but it requires complex and software-specific input data formats.

A. Marcia Barbosa

Schoener T.W. (1968) Anolis lizards of Bimini: resource partitioning in a complex fauna. Ecology 49: 704-726

van der Vaart A.W. (1998) Asymptotic statistics. Cambridge Univ. Press, Cambridge (UK)

Warren D.L., Glor R.E. & Turelli M. (2008) Environmental niche equivalency versus conservatism: quantitative approaches to niche evolution. Evolution, 62: 2868-83 (and further ERRATUM)

`fuzSim`

; `niche.overlap`

in package phyloclim

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | ```
# get an environmental favourability model for a rotifer species:
data(rotif.env)
names(rotif.env)
fav_current <- multGLM(rotif.env, sp.cols = 18, var.cols = 5:17,
step = TRUE, FDR = TRUE, trim = TRUE, P = FALSE, Fav = TRUE) $
predictions
# imagine you have a model prediction for this species in a future time
# (here we will create one by randomly jittering the current predictions)
fav_imag <- jitter(fav_current, amount = 0.2)
fav_imag[fav_imag < 0] <- 0
fav_imag[fav_imag > 1] <- 1
# calculate niche overlap between current and imaginary future predictions:
modOverlap(fav_current, fav_imag)
``` |

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