101-16 Diversity-Disparity Dynamics Vary Significantly Across Major Marine Animal Clades

Session: Paleontology, Biogeography/Biostratigraphy & Phylogenetic/Morphological Patterns

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Decades of studying disparity have yielded few consistent patterns regarding the morphological and ecological impacts during major diversifications. Early bursts can accrue innovation more rapidly than the number of radiating lineages, disparity can expand in a concordant fashion with a clade's diversification, or disparity can lag behind diversity. In a series of papers in Evolutionary Biology, David Jablonski (1997a,b, 2022) proposed using "diversity-disparity plots" to more systematically document these dynamics, regardless of clade, time interval, or environmental circumstance. Drawing on a database of the life habits of all marine genera in the Paleobiology Database, here I compare diversity-disparity dynamics for major clades (phyla and classes) throughout their evolutionary histories. Most clades have volatile Phanerozoic diversity-disparity trends that move idiosyncratically throughout this space. Several clades—including trilobites, chondrichthyans, crinoids, and echinoids—have trends that fall close to the 1:1 line, suggesting ecological innovation generally tracks lineage diversity in these taxa. Clades with higher-than-expected evolvability include arthropods (especially malacostracans), gymnolaemates, and Paleozoic chordates and mollusks, while those exemplifying lower evolvability include Paleozoic echinoderms and post-Paleozoic chordates. The wide range of diversity-disparity trends observed among marine taxa suggests clade-specific limits to evolvability rather than generalizable artifacts of evolutionary diversification. This research has been supported by NSF grant #2322080.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8185

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