Like Products, Plants Wait for Optimal Configuration Before Market Success
ScienceDaily (Mar. 30, 2011) — An international research team led by Brown University has amassed the largest evolutionary tree (phylogeny) for plants. It has learned that major groups of plants tinker with their design and performance before rapidly spinning off new species. The finding upends long-held thinking that plants' speciation rates are tied to the first development of a new physical trait or mechanism.
Botanical market testing Botanists had long thought that new species proliferate soon after plants developed a new physical trait. Stephen Smith and colleagues have shown that plants may bide their time for undergoing major speciation. (Credit: Mike Cohea/Brown University)
Results are published in theAmerican Journal of Botany.
Just as a company creates new, better versions of a product to increase market share and pad its bottom line, an international team of researchers led by Brown University has found that plants tinker with their design and performance before flooding the environment with new, improved versions of themselves.
The issue: When does a grouping of plants with the same ancestor, called a clade, begin to spin off new species? Biologists have long assumed that rapid speciation occurred when a clade first developed a new physical trait or mechanism and had begun its own genetic branch. But the team, led by Brown postdoctoral research associate Stephen Smith, discovered that major lineages of flowering plants did not begin the rapid spawning of new species until they had reached a point of development at which speciation success and rate would be maximized. The results are published in the American Journal of Botany.
"Evolution is not what we previously thought," said Smith, who works in the laboratory of Brown biologist Casey Dunn. "It's not as if you get a flower, and speciation (rapidly) occurs. There is a lag. Something else is happening. There is a phase of product development, so to speak."...
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First published online March 2, 2011; doi:10.3732/ajb.1000481American Journal of Botany 98: 404-414 (2011)
Understanding angiosperm diversification using small and large phylogenetic trees1
Stephen A. Smith2,3,5, Jeremy M. Beaulieu4, Alexandros Stamatakis3 and Michael J. Donoghue4
2 Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912 USA 3 Scientific Computing Group, Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg, Germany 4 Department of Ecology and Evolutionary Biology, Yale University, P.O. Box 208105, New Haven, Connecticut 06520 USA
ABSTRACT
How will the emerging possibility of inferring ultra-large phylogenies influence our ability to identify shifts in diversification rate? For several large angiosperm clades (Angiospermae, Monocotyledonae, Orchidaceae, Poaceae, Eudicotyledonae, Fabaceae, and Asteraceae), we explore this issue by contrasting two approaches: (1) usingsmall backbone trees with an inferred number of extant species assigned to each terminal clade and (2) using a mega-phylogeny of 55473 seed plant species represented in GenBank. The mega-phylogeny approach assumes that the sample of species in GenBank is at least roughly proportional to the actual species diversity of different lineages, as appears to be the case for many major angiosperm lineages. Using both approaches, we found that diversification rate shifts are not directly associated with the major namedclades examined here, with the sole exception of Fabaceae in the GenBank mega-phylogeny. These agreements are encouraging and may support a generality about angiosperm evolution: major shifts in diversification may not be directly associated with major named clades, but rather with clades that are nested not far within these groups. An alternative explanation is that there have been increased extinction rates in early-diverging lineages within these clades. Based on our mega-phylogeny, the shifts in diversification appear to be distributed quite evenly throughout the angiosperms. Mega-phylogenetic studies of diversification hold great promise for revealing new patterns, but we will need to focus more attention on properly specifying null expectation.
Key Words: angiosperms • diversification rate • flowering plants • key innovation • mega-phylogeny
Received for publication 24 November 2010. Accepted for publication 11 February 2011.
FOOTNOTES
1 We thank Peter Raven, J. Chris Pires, and Jon Chase for inviting us to contribute to this special issue. We are grateful to the National Science Foundation for supporting this research through the CIPRES and Angiosperm ATOL projects and through the iPToL grand challenge project supported by the iPlant Collaborative. Part of this work was also supported by the German Science Foundation (DFG) under the auspices of the Emmy-Noether program. Computational work was made possible by the facilities and the helpful staff of the Yale University High Performance Computing Center and by John Cazes at the Texas Advanced Computing Center.
5 Author for correspondence: stephen_a_smith@brown.edu
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Key Words: angiosperms • diversification rate • flowering plants • key innovation • mega-phylogeny
Received for publication 24 November 2010. Accepted for publication 11 February 2011.
FOOTNOTES
1 We thank Peter Raven, J. Chris Pires, and Jon Chase for inviting us to contribute to this special issue. We are grateful to the National Science Foundation for supporting this research through the CIPRES and Angiosperm ATOL projects and through the iPToL grand challenge project supported by the iPlant Collaborative. Part of this work was also supported by the German Science Foundation (DFG) under the auspices of the Emmy-Noether program. Computational work was made possible by the facilities and the helpful staff of the Yale University High Performance Computing Center and by John Cazes at the Texas Advanced Computing Center.
5 Author for correspondence: stephen_a_smith@brown.edu
Key Words: angiosperms • diversification rate • flowering plants • key innovation • mega-phylogeny
Received for publication 24 November 2010. Accepted for publication 11 February 2011.
FOOTNOTES
1 We thank Peter Raven, J. Chris Pires, and Jon Chase for inviting us to contribute to this special issue. We are grateful to the National Science Foundation for supporting this research through the CIPRES and Angiosperm ATOL projects and through the iPToL grand challenge project supported by the iPlant Collaborative. Part of this work was also supported by the German Science Foundation (DFG) under the auspices of the Emmy-Noether program. Computational work was made possible by the facilities and the helpful staff of the Yale University High Performance Computing Center and by John Cazes at the Texas Advanced Computing Center.
5 Author for correspondence: stephen_a_smith@brown.edu
