  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.
