| Paper No. 58-0 | ||
| LITERATURE-BASED CHARACTERS AS A SOURCE OF NON-RANDOM BIAS IN PHYLOGENETIC ANALYSES | ||
|
MARCUS, Sara A., Department of Geology, University of Kansas, 120 Lindley Hall, Lawrence, KS 66045, current: Indiana University Dept. of Geological Sciences, 1001 E. 10th St, Bloomington, IN 47405, samarcus@indiana.edu. Phylogenetic trees that include fossil taxa often are generated from a matrix of literature-based characters. This practice can introduce undesirable, non-biological, non-random patterns into the final trees. Literature-based character descriptions are used for a number of reasons: lack of access to specimens, lack of time to examine representative specimens due to taxonomic diversity within the chosen group, or lack of taxonomically intimate knowledge of the group being analyzed. Even if the most current references for a group are used, errors often are perpetuated through the literature. In addition, old photographs and line drawings may be inaccurate or may not show needed characters, leading to incorrect coding of characters. The approach of using literature-based characters can lead to biases in the final trees that may not be immediately apparent until actual type specimens are used to determine characters for creating phylogenies. Using only literature-based characters, trees were generated for species of the crinoid genus Allagecrinus (Crinoidea, Disparida). Distributions of terminal taxa on consensus trees were not related to stratigraphic distribution or paleobiogeography; rather, taxa were distributed by original author with taxa described by the same author showing the closest relationships. When type specimens of Allagecrinus species were examined, many original published descriptions and illustrations were corrected and clarified. A new matrix was created using these specimen-based observations, and the same parameters were used to create consensus trees. The resulting distribution of species was no longer by author, but rather reflected a temporal distribution. This example demonstrates at least one source of non-random bias that may occur using only literature-derived characters, and shows that assessment of characters using specimens can dramatically affect distribution of terminal taxa. Phylogenies on higher taxonomic levels may not need finer-scale characters that species- or genus-level phylogenies necessitate and may be buffered from this effect. | ||
|
GSA Annual Meeting, November 5-8, 2001
General Information for this Meeting | ||
| Session No. 58 Paleontology I: Assessing Biodiversity Hynes Convention Center: 106 8:00 AM-12:00 PM, Tuesday, November 6, 2001 | ||
© Copyright 2001 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions. | ||