Testing the stability of marine communities over multiple timescales of eustatic cyclicity

Abstract

This study tests the stability of marine communities, measured by Hubbell’s fundamental biodiversity number θ, over multiple timescales of sea-level change. Estimates of θ are calculated for newly collected and existing faunal censuses of third, fourth, and fifth-order sequences of the Late Ordovician Mohawkian and Cincinnatian Series. Results indicate that the value of θ remains relatively constant from one sequence to the next, for fourth and fifth-order sequences, suggesting that these communities are able to rapidly respond to changes in habitat area. Third-order M6, C2, and C3 sequences exhibit consistent values of θ, however values of θ for the M5, C4, and C5 sequences are elevated and may be related to increased turnover or metacommunity area. Additionally, values of θ for third-order sequences are substantially larger than those of fourth-order and fifth-order sequences, but this pattern may reflect differences in experience among those performing faunal censuses rather than ecological factors.