Environmental changes define ecological limits to species richness and reveal the mode of macroevolutionary competition

• Published in: Ecology Letters
• Main Authors: Ezard, THG, Purvis, A
• Other Authors: The Leverhulme Trust
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Wiley 2016
• Subjects: Beverton-Holt; Ricker; contest competition; diversification; diversity-dependence; ecological limits; microfossil; scramble competition; Ecology; 0501 Ecological Applications; 0602 Ecology; Planktonic foraminifera
• Online Access: http://hdl.handle.net/10044/1/31887; https://doi.org/10.1111/ele.12626

© 2016 The Authors. Ecology Letters published by CNRS and John Wiley & Sons Ltd.Co-dependent geological and climatic changes obscure how species interact in deep time. The interplay between these environmental factors makes it hard to discern whether ecological competition exerts an upper limit on species richness. Here, using the exceptional fossil record of Cenozoic Era macroperforate planktonic foraminifera, we assess the evidence for alternative modes of macroevolutionary competition. Our models support an environmentally dependent macroevolutionary form of contest competition that yields finite upper bounds on species richness. Models of biotic competition assuming unchanging environmental conditions were overwhelmingly rejected. In the best-supported model, temperature affects the per-lineage diversification rate, while both temperature and an environmental driver of sediment accumulation defines the upper limit. The support for contest competition implies that incumbency constrains species richness by restricting niche availability, and that the number of macroevolutionary niches varies as a function of environmental changes.