Estimating Age-Dependent Extinction: Contrasting Evidence from Fossils and Phylogenies

Author(s)

Hagen, Oskar ^{[1, 2, 3]} ; Andermann, Tobias ^{[1, 4]} ; Quental, Tiago B. ^[5] ; Antonelli, Alexandre ^{[1, 4, 6]} ; Silvestro, Daniele ^{[1, 4, 7]}

Affiliation

^[1] Univ Gothenburg, Dept Biol & Environm Sci, SE-40530 Gothenburg - Sweden

^[2] Swiss Fed Res Inst WSL, CH-8903 Birmensdorf - Switzerland

^[3] Swiss Fed Inst Technol, Inst Terr Ecosyst, Landscape Ecol, CH-8092 Zurich - Switzerland

^[4] Gothenburg Global Biodivers Ctr, Box 461, SE-40530 Gothenburg - Sweden

^[5] Univ Sao Paulo, Dept Ecol, BR-05508900 Sao Paulo - Brazil

^[6] Gothenburg Bot Garden, Carl Skottsbergs Gata 22A, SE-41319 Gothenburg - Sweden

^[7] Univ Lausanne, Dept Computat Biol, CH-1015 Lausanne - Switzerland

• Document type: Journal article
• Source: Systematic Biology; v. 67, n. 3, p. 458-474, MAY 2018.
• Web of Science Citations: 7

Abstract

The estimation of diversification rates is one of the most vividly debated topics in modern systematics, with considerable controversy surrounding the power of phylogenetic and fossil-based approaches in estimating extinction. Van Valen's seminal work from 1973 proposed the ``Law of constant extinction,{''} which states that the probability of extinction of taxa is not dependent on their age. This assumption of age-independent extinction has prevailed for decades with its assessment based on survivorship curves, which, however, do not directly account for the incompleteness of the fossil record, and have rarely been applied at the species level. Here, we present a Bayesian framework to estimate extinction rates from the fossil record accounting for age-dependent extinction (ADE). Our approach, unlike previous implementations, explicitly models unobserved species and accounts for the effects of fossil preservation on the observed longevity of sampled lineages. We assess the performance and robustness of our method through extensive simulations and apply it to a fossil data set of terrestrial Carnivora spanning the past 40 myr. We find strong evidence of ADE, as we detect the extinction rate to be highest in young species and declining with increasing species age. For comparison, we apply a recently developed analogous ADE model to a dated phylogeny of extant Carnivora. Although the phylogeny-based analysis also infers ADE, it indicates that the extinction rate, instead, increases with increasing taxon age. The estimated mean species longevity also differs substantially, with the fossil-based analyses estimating 2.0 myr, in contrast to 9.8 myr derived from the phylogeny-based inference. Scrutinizing these discrepancies, we find that both fossil and phylogeny-based ADE models are prone to high error rates when speciation and extinction rates increase or decrease through time. However, analyses of simulated and empirical data show that fossil-based inferences are more robust. This study shows that an accurate estimation of ADE from incomplete fossil data is possible when the effects of preservation are jointly modeled, thus allowing for a reassessment of Van Valen's model as a general rule in macroevolution. (AU)

• FAPESP's process: 12/04072-3 - The role of extinction and speciation rates, and the effect of different levels of biological organization on the origin and maintenance of biodiversity
• Grantee: Tiago Bosisio Quental
• Support Opportunities: Research Grants - Young Investigators Grants