Biodiversity on island chains: neutral model simulations

A neutral ecology model is simulated on an island chain, in which neighbouring islands can exchange individuals but only the first island is able to receive immigrants from a metacommunity. It is found by several measures that biodiversity decreases along the chain, being highest for the first island. Subtle changes in taxon abundance distributions can be detected when islands in the chain are compared to diversity-matched single islands. The results potentially apply to human microbial diversity, but highlight the difficulty of using static single-site taxon abundance distributions to discriminate between dispersal limitation mechanisms.Comment: 6 pages, 6 figures, RevTeX

Flory-Huggins theory for the solubility of heterogeneously-modified polymers

Many water soluble polymers are chemically modified versions of insoluble base materials such as cellulose. A Flory-Huggins model is solved to determine the effects of heterogeneity in modification on the solubility of such polymers. It is found that heterogeneity leads to decreased solubility, with the effect increasing with increasing blockiness. In the limit of extreme blockiness, the nature of the phase coexistence crosses over to a polymer-polymer demixing transition. Some consequences are discussed for the synthesis of partially modified polymers, and the experimental characterisation of such systems.Comment: 4 pages, 2 figures, RevTeX 4.