[Ocees] Evolutionary biology of awesome fossil arthropods in this week's geology colloquium

[Stigall, Alycia]

Join us this week for the Geological Sciences colloquium featuring cool evolutionary biology (niches, morphospace, and heterochony, on my!) of seriously awesome fossils! with Dr. James Lamsdell of West Virginia University.

Also, let me know if you like to meet with James—he’ll be around from 11am until 2pm for meetings/lunch.  James does a lot of work in phylogenetics and also weird fossils (including the Tully monster).

Thanks!
Alycia

Geological Sciences colloquium
April 20 @ 2:00 pm in Clippinger 205

Exploring environmental drivers of morphological change in horseshoe crabs and sea scorpions
James Lamsdell, Assistant Professor
West Virginia University Department of Geology and Geography

Abstract: The importance of both intrinsic biological and external environmental factors in defining macroevolutionary patterns has been recognized since its popularization by G. G. Simpson. However, there is still much discussion about how the genealogical and ecological hierarchies interact, the outcome of these interactions on patterns of morphospace occupation, and the general repeatability of the evolutionary outcome of any given situation. Of particular interest are the drivers of morphological innovation and whether novel morphologies are associated with shifts in Hutchinsonian niche. Phylogenetic paleoecology, combining tree-based frameworks of relationships with geologic paleoenvironmental data, is one way to explore how clades respond to broad-scale changes in environment. Arthropods are an excellent group on which to conduct such studies due to their character-rich hard external exoskeleton. Combining studies of phylogeny, empirical morphospace, and environmental occupation, I compare variations in ecology and morphospace across the evolutionary history of two Paleozoic arthropod groups, the Eurypterida and Xiphosurida. Both groups undergo a change in evolutionary regime during the Late Devonian, linked to an ecological transition from marine to freshwater environments. In eurypterids the change manifests as a reduction in diversity with the surviving lineage exhibiting low disparity alongside a decrease in endemism, with new species exhibiting general peramorphic morphological trends. Xiphosurids, however, show the opposite trend, with the invasion of non-marine environments resulting in a shift away from bradytely and a proliferation of new pedomorphic species that occupy novel regions of morphospace. Interestingly, other xiphosurid groups that invade non-marine environments during the Mesozoic show a similar ecological pattern of differentiation, speciation and subsequent extinction. Shifts in ecology therefore have long-term impacts on a lineage’s macroevolutionary trajectory, with eurypterids experiencing a permanent shift in morphospace in response to the regime change in the Devonian. Importantly, intrinsic factors within lineages (peramorphic vs. pedomorphic trends) appear as important as external (ecologic) elements in mediating morphological innovation.

https://www.ohio-forum.com/2018/04/geology-colloquium-exploring-environmental-drivers-of-morphological-change-in-horseshoe-crabs-and-sea-scorpions-april-20/
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***************************
Alycia L. Stigall
Professor
Department of Geological Sciences
OHIO Center for Ecology and Evolutionary Studies
Ohio University
316 Clippinger Laboratories
Athens, Ohio 45701
(740) 593-0393
stigall at ohio.edu<applewebdata://0A7DDF58-741D-4DD0-9C51-6F5CCDE681FA/compose/?adb_to=stigall@ohio.edu>
http://alyciastigall.org<http://alyciastigall.org/> (My lab website)
http://www.ohio.edu/paleo (OHIO Paleo program)
Paleontological Society Treasurer


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