Abstract Detail



Fossil plants at the intersection of evo-devo and phylogeny: celebrating the contributions of Gar W. Rothwell to biodiversity and evolution

Pigg, Kathleen [1], DeVore, Melanie [2].

Morphological features of Eocene sumac leaves (Rhus, Anacardiaceae) linked with hybridization.

The fossil taxon Rhus malloryi Wolfe and Wehr was described in their 1987 monographic treatment of the latest early Eocene Republic, Washington flora on the basis of a small number of specimens. Today, after more than 30 years of collecting by professionals and the public at the Boot Hill site under the auspices of the Stonerose Interpretive Center, a much larger sample of a wide array of Rhus specimens are available to us. Clearly the specimens identified as "Rhus malloryi" represent multiple species of Rhus, and perhaps other taxa. Many appear to have asymmetrical leaves or leaflets, a condition that often occurs among hybrids that is the result of fluctuating asymmetry. Higher order venation patterns are also often disrupted as well. In extant hybrids, these unusual appearances associated with fluctuating asymmetry result from the disruption of coadapted gene complexes by hybridization. These patterns of changes in leaf morphology appear to be independent of standard parameters used to document leaf variation such as differences in distance between midrib and leaf margin. There appears to be a greater variation in larger-scale morphological features of the leaf, for example, variously fused leaflets and highly asymmetrical leaf venation. Interestingly, these patterns are found in extant members of one subgenus of Rhus, subgenus Lobadium. Phylogenetic and biogeographical analyses have suggested that Rhus initially diverged into an eastern Asian lineage, subgenus Rhus and second North American lineage, subgenus Lobadium, that is distributed primarily in the western US and extending into Mexico, with one species ranging from southern Mexico into Guatemala. Numerous episodes of hybridization have been linked with species within Lobadium and the subgenus includes endemics in California. From the results of our analyses of Rhus leaves from Republic, it appears that the Lobadium complex could represent a perpetual group of species which has spawned hybrids and endemic taxa for nearly 50 million years.


1 - Arizona State University, School Of Life Sciences, PO Box 874501, Tempe, AZ, 85287, United States
2 - Dept Of Biology & Env. Science, GC & SU Campus Box 81, Milledgeville, GA, 31061, United States

Keywords:
Rhus
Anacardiaceae
fossil
fluctuating asymmetry
Hybridization
Eocene
Republic flora.

Presentation Type: Colloquium Presentations
Session: C11, Fossil plants at the intersection of evo-devo and phylogeny: celebrating the contributions of Gar W. Rothwell to biodiverstiy and evolution (Copy)
Location: 110/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 11:15 AM
Number: C11011
Abstract ID:749
Candidate for Awards:None


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