Function to calculate the minimum size ratio (larger/next larger) between species within an assemblage.
a vector of non-negative trait measures, one for each species
This index is based on the minimum size ratio (larger/next larger) difference between consecutively ordered species in an assemblage. It is appropriate for morphological traits, but not phenological ones.
Returns the minimum size ratio difference between adjacent, ordered values.
Simberloff, D. and W.J. Boecklen. 1981. Santa Rosalia reconsidered: size ratios and competition. Evolution 35: 1206-1228.