Relative biodiversity trends of the Cenozoic Caribbean region: Investigations of possible causes and issues of scale using a biostratigraphic database of corals, echinoids, bivalves and gastropods.

摘要

New metrics are presented that reduces the effect of uneven distribution of fossils across time and space. The Diversity Index of Growth (DIG) measures relative change of biodiversity by examining four key parameters of biodiversity obtained from biostratigraphic data: New, Extinct, Stable and Total. In this study, DIG was utilized to examine biodiversity trends of a Cenozoic Caribbean marine invertebrate database. The results indicate that the individual class-level trends observed from the database are consistent with previously interpreted trends. Key features of the observed biodiversity trends of the Caribbean include three peaks of diversification, including increased biodiversity near the Paleocene-Eocene Thermal Maximum (PETM). Marine invertebrate biodiversity appears to be linked to a variety of environmental processes, including volcanism and climate change. The timing of biodiversity increases corresponds to increases in sea-level and three major volcanic episodes in the Caribbean. The positive relationship between sea-level increases and biodiversification is observed at several spatial-temporal scales, and indicates that relative biotic diversity change may be useful for following highstand facies or for sequence stratigraphy applications. Climate effects, as interpreted from isotopic data and terrestrial data, also suggest a potential agreement between climate, sea-level and biodiversity. The effects of scale and hierarchy from temporal, spatial and taxonomic perspectives are also investigated as is the problem of comparing data of differing levels of spatial-temporal resolution. A new metric is introduced to understand and quantify the relative degree of resolution achievable by a database. Sensitivity of Data (SOD) gives a measurement of the spatial, temporal, and observational extent over which the interpretations gleaned from a database are valid. In many instances, the potentially differing interpretations made from the same or similar data may be attributed to variation in the spatio-temporal sensitivity of the data, or the environmental processes to which they are compared. I hypothesize that the sensitivity of the data contributes to the assignment of various environmental processes as higher or lower hierarchies that impart differential control to the biosphere. These higher- and lower-orders of processes likely may originate only because of variation in the quality and quantity of observations used to interpret past events.