Spiny plants, mammal browsers, and the origin of African savannas

Tristan Charles-Dominique, T. Jonathan Davies, Gareth P. Hempson, Bezeng S. Bezeng, Barnabas H. Daru, Ronny M. Kabongo, Olivier Maurin, A. Muthama Muasya, Michelle Van Der Bank, William J. Bond

Research output: Contribution to journalArticlepeer-review

127 Citations (Scopus)

Abstract

Savannas first began to spread across Africa during the Miocene. A major hypothesis for explaining this vegetation change is the increase in C4 grasses, promoting fire. We investigated whether mammals could also have contributed to savanna expansion by using spinescence as a marker of mammal herbivory. Looking at the present distribution of 1,852 tree species, we established that spinescence is mainly associated with two functional types of mammals: large browsers and medium-sized mixed feeders. Using a dated phylogeny for the same tree species, we found that spinescence evolved at least 55 times. The diversification of spiny plants occurred long after the evolution of Afrotherian proboscideans and hyracoids. However, it is remarkably congruent with diversification of bovids, the lineage including the antelope that predominantly browse these plants today. Our findings suggest that herbivore-adapted savannas evolved several million years before fire-maintained savannas and probably, in different environmental conditions. Spiny savannas with abundant mammal herbivores occur in drier climates and on nutrient-rich soils, whereas fire-maintained savannas occur in wetter climates on nutrient-poor soils.

Original languageEnglish
Pages (from-to)E5572-E5579
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number38
DOIs
Publication statusPublished - 20 Sept 2016

Keywords

  • Africa
  • Bovidae
  • Coevolution
  • Mammalian herbivory
  • Savanna

ASJC Scopus subject areas

  • Multidisciplinary

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