The rise of angiosperms pushed conifers to decline during global cooling

  • Fabien L. Condamine, Daniele Silvestro, Eva B. Koppelhus, Alexandre Antonelli
  • Proceedings of the National Academy of Sciences, November 2020, Proceedings of the National Academy of Sciences
  • DOI: 10.1073/pnas.2005571117

Flowers outcompeted conifers since the Cretaceous

Photo by Bruno Salvini on Unsplash

Photo by Bruno Salvini on Unsplash

What is it about?

We evaluated the long-held hypothesis that the radiation of angiosperms (flowering plants) has led to the decline of gymnosperms (here approximated by conifers). Using approaches based on dated molecular phylogenies or paleontological data, we estimated processes of conifer diversification and how they relate to different external factors. The diversity of conifers is strongly and directly linked to the increasing diversity of flowering plants since the Cretaceous period, thus attesting to the role of competition between plants.

Why is it important?

The study of an ancient and relatively species-poor group of plants deepens our understanding of how diversity is regulated over time and in relation to multiple factors. Both phylogenetic and fossil data provide strong support for a widespread hypothesis of competition between clades over time. This study illustrates how entire branches of the tree of life can actively compete for ecological dominance under changing climatic conditions.

Perspectives

Fabien Condamine
CNRS

Working on this long-standing hypothesis was exciting because studying deep-time interactions between groups is challenging. This study lays the foundation for the use of macroevolutionary models applied to ecological questions. One remaining mystery we could not address in this study is the astonishingly low global diversification rates of conifers. In conifers, I think their low diversification could be due to their biological features, but this remains to be investigated in detail. For instance, compared to flowering plants, conifers grow slowly, reach sexual maturity very late, leading to long generation times and as a consequence it leads to a lower potential for adaptation. Put in other words, it means that some conifers are only able to breed after 20 years of growth, while at the same time many flowering plants would be able to breed almost 20 times. Such a ontogeny and reproduction strategies could make conifer diversification slow.

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http://dx.doi.org/10.1073/pnas.2005571117

The following have contributed to this page: Fabien Condamine