Appearance and disappearance rates of Phanerozoic marine animal paleocommunities

A.D Muscente,Robert M Hazen,Anirudh Prabhu,Andrew H Knoll,Rowan C Martindale,Peter Fox,Xiaogang Ma

doi:10.1130/g49371.1

Abstract

AbstractEcological observations and paleontological data show that communities of organisms recur in space and time. Various observations suggest that communities largely disappear in extinction events and appear during radiations. This hypothesis, however, has not been tested on a large scale due to a lack of methods for analyzing fossil data, identifying communities, and quantifying their turnover. We demonstrate an approach for quantifying turnover of communities over the Phanerozoic Eon. Using network analysis of fossil occurrence data, we provide the first estimates of appearance and disappearance rates for marine animal paleocommunities in the 100 stages of the Phanerozoic record. Our analysis of 124,605 fossil collections (representing 25,749 living and extinct marine animal genera) shows that paleocommunity disappearance and appearance rates are generally highest in mass extinctions and recovery intervals, respectively, with rates three times greater than background levels. Although taxonomic change is, in general, a fair predictor of ecologic reorganization, the variance is high, and ecologic and taxonomic changes were episodically decoupled at times in the past. Extinction rate, therefore, is an imperfect proxy for ecologic change. The paleocommunity turnover rates suggest that efforts to assess the ecological consequences of the present-day biodiversity crisis should focus on the selectivity of extinctions and changes in the prevalence of biological interactions.

Highlights

In modern ecosystems, species associate in recurrent communities that reflect biological interactions, overlapping environmental tolerances, or both (Liautaud et al, 2019)
A local paleocommunity corresponds to all of the species observed in one bed at a single outcrop, but because assigning fossils to species can be challenging, and boundaries among beds and outcrops are unclear in some cases, paleocommunity analyses commonly focus on broadly defined samples of fossils classified by genus
Paleocommunity Turnover Rates The number of paleocommunities rises and falls across the record, with peaks in the Ordovician, Permian, Cretaceous, and Paleogene (Fig. 1A; Fig. S6). Their corrected sampled-in-bin (CSIB) number broadly covaries with the total CSIB number of genera, or gamma diversity (Whittaker, 1960); the number of paleocommunities significantly departs from gamma diversity in the middle Paleozoic (Silurian and Devonian) and Neogene

Summary

Introduction

Species associate in recurrent communities that reflect biological interactions, overlapping environmental tolerances, or both (Liautaud et al, 2019). To confirm that the modules represent paleocommunities, we examined the network for homophily, or the tendency of links to connect nodes with similar properties, by calculating “assortativity coefficients” for various variables (e.g., age, location, environment, and lithology). To quantify the number and turnover of genera and paleocommunities in each Phanerozoic stage, we adapted common metrics of taxonomic change.

Results

Conclusion