Convergent Evolution

by

Luke J. Harmon

• LAST REVIEWED: 13 January 2014
• LAST MODIFIED: 13 January 2014
• DOI: 10.1093/obo/9780199941728-0038

Introduction

Convergent evolution is typically defined as the repeated evolution of similar traits in independent evolutionary lineages inhabiting similar environments. Convergence has played a key role in evolutionary biology in at least three ways. First, convergent evolution provides natural replicates that can be used to address general questions in the field that transcend the limitations of studying single evolutionary events. Second, convergent evolution has notoriously confounded studies that attempt to estimate phylogenetic relationships among species; only by identifying convergent traits can we hope to uncover the shared derived characters that denote historical relationships among species. Finally, the overall prevalence of convergence speaks to the long-term predictability of evolution. Studies of convergent evolution have a long history in both paleontology and phylogenetic systematics, and remarkable examples of the convergent evolution of traits, organisms, and even whole communities have been identified and described. However, the interpretation of convergent evolution is not without controversy. Some view convergent evolution as ubiquitous across the tree of life, thus marking the predictability of evolution even over long time scales. Others view convergent evolution as a rare fluke of evolution, and believe that evolution is dominated by chance events. Additionally, some evolutionary biologists view convergent evolution as the result of deterministic natural selection and adaptation, while others see the mark of genetic and/or developmental constraints. Recent advances in evolutionary developmental biology and genomics have given us a wealth of new information about the mechanisms of convergent evolution. This work has focused on the genetics of adaptation, and in separating cases of parallelism—a special case of convergent evolution where independent evolutionary lineages evolve the same trait using the same genes and/or developmental pathways—from convergence, where lineages evolve similar traits using unique developmental pathways.

General Overviews

Review papers and textbooks, such as Futuyma 2013 tend to focus on how one can identify convergent evolution and on presenting particularly compelling examples of convergence or lack thereof. A few authors have attempted to make broad generalizations based on these observations. Gould 1990 argues that evolution is dominated by historical contingency, while Conway Morris 2004 (see also papers in Conway Morris 2008) and McGee 2011 argue that convergence is ubiquitous. Conway Morris 2004 argues for both adaptive and constraint-based mechanisms for convergence, while McGee 2011 leans most heavily on constraints as a mechanism. Losos 2011 is a nice early-21st-century review paper that carefully describes what we can (and cannot) learn from studies of convergent evolution.

• Conway Morris, Simon. 2004. Life’s solution: Inevitable humans in a lonely universe. Cambridge, UK: Cambridge Univ. Press.

  This book catalogues convergent evolution across a wide range of taxa and time scales. Conway Morris argues that convergence is common and that the universe is predictable—even going so far as to argue for the inevitability of the evolution of our own species.

• Conway Morris, Simon, ed. 2008. The deep structure of biology: Is convergence sufficiently ubiquitous to give a directional signal? West Conshohocken, PA: Templeton Foundation.

  This edited volume includes chapters on a wide range of topics in convergent evolution, including both empirical results and philosophical considerations.

• Futuyma, Douglas J. 2013. Evolution. Sunderland, MA: Sinauer.

  This now-classic textbook discusses convergent evolution explicitly in Chapter 3 (Patterns of Evolution), but the topic also appears in several other contexts and chapters.

• Gould, Steven J. 1990. Wonderful life: The Burgess Shale and the nature of history. New York: W. W. Norton.

  Gould’s classic book uses the Burgess Shale—a fossil field with exceptional preservation of the soft body parts of an astounding assortment of middle Cambrian fossils—as an argument in favor of the role of chance and contingency in evolution.

• Losos, Jonathan B. 2011. Convergence, adaptation, and constraint. Evolution 65:1827–1840.

  DOI: 10.1111/j.1558-5646.2011.01289.x

  An excellent review focusing on what we can (and cannot) conclude from examples of convergent evolution. Losos argues that other forms of evidence (beyond phenotypic similarity) are needed to distinguish adaptive convergence from convergence due to genetic or developmental constraint.

• McGee, George. 2011. Convergent evolution: Limited forms most beautiful. Cambridge, MA: MIT Press.

  McGee reviews a multitude of examples of convergent evolution, from genes to phenotypes to behavior, and argues that the ubiquity of convergent evolution is mainly due to functional and developmental constraints.