T44 Across Space and through Time: Understanding Evolution and Ecology Using Biogeography II

Sunday, 25 September 2016
1:30 PM - 5:30 PM
Mile High Ballroom 3C

MOSAIC EVOLUTION IN THE MIDDLE MIOCENE PLANKTONIC FORAMINIFERA GLOBOROTALIA FOHSI LINEAGE

Paper number: T44-8
Program: Technical Sessions
Time: 3:15 PM – 3:30 PM

Authors

Abstract

Recent studies have shown that modes of evolution, including directional trend, random walk, and stasis, vary across morphologic traits and over geographic ranges (Grey et al., 2008; Hopkins & Lidgard, 2012, Hunt et al., 2015). If so, is it possible that our interpretation of evolutionary modes is actually driven by our selection of traits? In an attempt to answer this question, we restudied the Middle Miocene planktonic foraminifera (PF) Globorotalia fohsi lineage, an iconic example of gradual evolution (Bolli et al., 1985). In contrast to previous studies that focused on the gross morphology of specimens, we analyzed multiple phenotypic traits of which the biologic and ecologic significance is well understood in extant PF populations. We find that traits in this lineage did not evolve in concert. The timing and geographic pattern of changes in shape, coiling direction, size, and ecology were different. The evolution of the G. fohsi lineage is a mosaic combination of different evolutionary modes of different traits. The interpretation of gradual evolution in the fohsellid lineage is a biased reading of fossil records due to 1) overemphasis of the importance of type specimens as reference points of the various stages of the evolution of the G. fohsi lineage; 2) biased selection of the examined trait; 3) biased geographic coverage. Gradual evolution significantly underestimates the dynamic evolutionary history of the fohsellids.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-285252

© Copyright 2016 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.