A computer simulation based on individual births and deaths gives a biodiversity increasing from cold to warm climates, in agreement with reality. Complexity of foodwebs increases with time and at a higher rate at low latitudes, and there is a higher rate of species creation at low latitudes. Keeping many niches empty makes the results correspond more closely to natural gradients.
@article{arxiv.q-bio/0505016,
title = {Simulation of geographical trends in Chowdhury ecosystem model},
author = {Klaus Rohde and Dietrich Stauffer},
journal= {arXiv preprint arXiv:q-bio/0505016},
year = {2007}
}