Phylogenetics of Astragalus (and related Legumes)

   What is a phylogeny and what can it tell us about the origin and evolution of plants such as Astragalus ? Evolutionary biologists (e.g., paleontologists and systematists) are interested in understanding the patterns of life and the processes by which it has changed and diversified through time. Before they can attempt to reconstruct the diversity of forms and functions of once-living organisms, these organisms and their relationships to each other need to be placed in a proper framework or context. That context is phylogeny, essentially the study of the evolutionary history or "connections" between all groups of organisms that have ever lived, as understood by ancestor/descendant relationships. Such relationships are depicted using diagrams called cladograms, or simply trees, which are like genealogies of species or other taxa. Phylogenetics is the science of phylogeny, and is one part of the field of systematics. Systematics also includes taxonomy, the science of naming and classifying the diversity of life on Earth. Phylogenies or phylogenetic trees are really estimates used to infer evolutionary relationships and are produced using methods for reconstructing histories based on the analysis of shared attributes (e.g., biogeographic, molecular, morphological, and paleontological data) of both extant and extinct organisms. For more information about the theory behind and methods for reconstructing phylogenies, check out the Phylogenetic Systematics "exhibit" at the University of California's (Berkeley) award-winning Museum of Paleontology website, www.ucmp.berkeley.edu.

   On the pages below, we present the results of our published, largely molecular phylogenetic studies on Astragalus and related legume groups. In addition, we also present relevant phylogenies derived from cladistic analyses of both morphological and/or molecular data, or arrived at "intuitively", and published by other researchers. 

Trees based on cladistic analyses of morphological and molecular datasets 

• M. F. Wojciechowski, M. J. Sanderson, B. G. Baldwin, and M. J. Donoghue (1993), "Monophyly of aneuploid
  Astragalus (Fabaceae): Evidence from nuclear ribosomal DNA internal transcribed spacer sequences",
  American Journal of Botany 80: 711-722.
• M. J. Sanderson and M. F. Wojciechowski (1996), "Diversification rates in a temperate legume clade: Are there "so many species of Astragalus (Fabaceae)?", American Journal of Botany 83: 1488-1502.
• M. F. Wojciechowski, M. J. Sanderson, and J-M. Hu (1999), "Evidence on the monophyly of Astragalus (Fabaceae) and its major subgroups based on nuclear ribosomal DNA ITS and chloroplast DNA trnL intron data", Systematic Botany 24: 409-437, 1999.
• Phylogeny of family Fabaceae based on analyses of sequence variation in chloroplast gene rbcL (Doyle et al., 1997)
  

"Intuitive" Phylogenies and Other Schemes

• Genetic relationships in North American Astragalus depicted in M. E. Jones' Revision of North-American
  Species of Astragalus from 1923.
• Phylogeny of Astragalus sensu D. Podlech (1982), from his paper entitled (English translation)"New Aspects of
  the Evolution and Organization of the genus Astragalus L.", Mitteilungen der Botanischen Staatssammlung
  Munchen 18: 359-37.
  

Link to TreeBase, the database of phylogenetic information

 

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