Note to Mac users: RangeModel 5 does not work under Mac OS 10.7 (Lion). A new version may eventually be offered that will work with Lion. Meanwhile, Mac users will need to use a computer with Mac OS 10.6 (Snow Leopard) or earlier, or with Windows 7 (or earlier) under Parallels.

Window users are unaffected by this notice..

About RangeModel 5

RangeModel is an animated, graphical, freeware application designed to demonstrate the mechanism behind the mid-domain effect (MDE), with tools for exploring the effects of both theoretical and empirical range size frequency distributions (RSFDs) for one-dimensional domains.

In addition, RangeModel 5 can generate the mean predicted pattern of richness, and its 95% confidence intervals, for any arbitrary number of randomizations of range placement for either:

  1. continuous data, sampled at any arbitrary set of points within a continuous, one-dimenional domain,
  2. or discrete data, sampled at ordered sites within a one-dimensional domain.

What is the mid-domain effect (MDE)?

The mid-domain effect is the increasing overlap of species ranges towards the center of a shared, bounded domain due to geometric boundary constraints in relation to the distribution of species' range sizes, producing a peak or plateau of species richness towards the center of the domain. Domains may be spatial, temporal, or funcitional. The MDE References page at this site provides a guide to the growing literature on MDE.

Major Features of RangeModel

  • Easy-to-use, graphical interface with button and menu-driven commands.
  • Tools for exploring the role of several theoretical range size frequency distributions (RSFDs), with or without upper and lower ranges size thresholds.
  • Options to display and export realized range-size frequency distributions, realized midpoint distributions, and Stevens' Rapoport plots.
  • Tools for importing and visualizing empirical richness patterns, based on midpoint-range data.
  • Tools for randomizing the placement of empirical ranges (or any RSFDs input by the user) and for producing 95% confidence intervals (CIs) for random range placement, for either (1) a continous domain with continuous ranges, or for (2) a domain defined by a set of discrete, ordered points. For continuous domains, sampling is based on user-specified sampling points. For both continuous and discrete domains, the user may specify the number of randomizations.
  • Exports all results to delimited text files for analysis in Excel or statistics applications.
  • Highly uniform random number generation, based on strong hash encryption technology.
  • RangeModel is free.


RangeModel 4 runs native under Windows XP or Mac OS X (certified for OS 10.4), with native user interface on each platform.


Robert K. Colwell