Do phylogenetically and ecologically delimited adaptive zones affect our inference of age-dependent extinction?

Author(s)

Salatiel Gonçalves Neto

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2023-11-06

Examining board members

Tiago Bosisio Quental; Renan Maestri; Mathias Mistretta Pires; Daniela Munhoz Rossoni

• Advisor: Tiago Bosisio Quental

Abstract

According to Van Valen\'s seminal work (1973), extinction occurs at a constantly stochastic rate within ecologically homogeneous groups or adaptive zones, resulting in an equal chance of long and short-lived species going extinct. The Red Queen Hypothesis was suggested as a possible mechanism for this age-independent extinction rate, which has been named \"The Law of Constant Extinction. The challenge of defining these homogeneous groups is explicitly discussed in Van Valen\'s work (1973), which relates to the difficulty of identifying the pool of species belonging to a given adaptive zone. Higher taxa have been used as a practical approximation for such adaptive zones, and most studies have used a taxonomically or phylogenetically defined pool of species to test the \"Law of Constant Extinction\". However, it becomes clear that Van Valen fundamentally viewed adaptive zones through the lens of ecological factors when delving into the interpretation of the \"law of constant extinction\" and exploring the Red Queen hypotheses. In that respect, an ecologically defined pool of species would be more in line with Van Valen\'s original concept of the adaptive zone and his underlying Red Queen hypothesis. Using the Canidae fossil record and a Bayesian framework, we demonstrate that species pools defined either by phylogeny or ecology exhibit different age-dependent extinction dynamics. We find considerable variation in the age-dependent extinction signal (ADE), depending on the species pool choice, time window used, and taxonomic level. Within phylogenetic species pools, we observe mixed evidence for ADE, with both positive older species being more likely to go extinct (e.g., Hesperocyoninae and Borophaginae) and negative - younger species being more likely to go extinct (e.g., Caninae) trends. When subfamilies are consolidated into a single family-level analysis, we encounter either weak evidence for ADE or robust support for Age-independent extinction (AIE). Furthermore, within ecologically defined species pools, hypercarnivores consistently display strong evidence for positive age-dependent extinction, whereas non-hypercarnivores have strong evidence for negative age-dependent extinction. We also found that clades with a higher proportion of hypercarnivore species tended to display evidence for positive age-dependent extinction, while clades with fewer hypercarnivores tended to evidence for negative age-dependent extinction. These findings collectively emphasize that the choice of species pool significantly influences the observed age-dependent extinction dynamics, and that ecology has a relevant impact on determining the regime of age-dependent extinction. (AU)

• FAPESP's process: 21/04258-9 - Do phylogenetically and ecologically delimited adaptive zones affect our inference of age-dependent extinction?
• Grantee: Salatiel Gonçalves Neto
• Support Opportunities: Scholarships in Brazil - Master