Paleobiogeography

Inferring the past distribution of species and what influenced their changes in distributions through time and types of evolution they experienced, and the abiotic factors driving these patterns, is paleobiogeography.

Total diversity at the western equatorial ODP Hole 806B subtracted from diversity at three sites in the northwest Pacific that cross the Kuroshio Current Extension. We found that diversity is highest on the northern edge of the current, and has remained stable with changes through the last 12 million years. Figure from Lam and Leckie (in press).

Currently I work in two time periods inferring paleobiogeographic patterns: the Neogene and the Ordovician. I use species from both time periods to decipher the drivers of speciation, reconstruct dispersal paths of species, infer potential speciation types, and describe macroevolutionary patterns such as the latitudinal diversity gradient.

In the Neogene, I use the fossil record of planktic foraminifera to conduct paleobiogeographic analyses. This period of time saw the development of modern temperature gradients and ocean circulation patterns, with major warming events that are used as analogues to anthropogenic warming today. Mainly, I investigate how western boundary currents and their development contributed to plankton evolution and dispersal dynamics. The majority of the data that I use comes from plankton biostratigraphic analyses from Deep Sea Drilling Program, Ocean Drilling Program, and International Ocean Drilling/Discovery Program publications, as well as the primary literature, combined with my own datasets. These data can also be used to infer the development of and changes in the plankton latitudinal diversity gradient across major climate and tectonic events.

Estimated area histories (left) and most probable area histories (right) for blastozoan diploporan echinoderms across the Ordovician. Figure from Lam et al. (accepted).

In the Ordovician, I conduct paleobiogeographic analyses using marine invertebrates (e.g., brachiopods, trilobites, echinoderms). The Ordovician is a very interesting period of time. Within 41.6 million years, the Earth experience major carbon isotope excursions, a switch from a greenhouse to an icehouse world, a huge increase in biodiversity (the Great Ordovician Biodiversification Event), and a major mass extinctions (the Late Ordovician mass extinctions). Using paleobiogeography, I investigate the drivers of such a biodiversity increase, speciation types related to major geochemical excursions and climate events, and how these changed across different clades. The majority of my Ordovician analyses are phylogenetically-informed, meaning I use published phylogenetic hypotheses of species to model evolutionary patterns.

Publications Related to Paleobiogeography

Lam, A. R., Sheffield, S. L., and Matzke, N. J., Accepted. Estimating dispersal and evolutionary dynamics in diploporan blastozoans (Echinodermata) across the Great Ordovician Biodiversification Event. Paleobiology. 

Lam, A. R., and Leckie, R. M., In press. Late Neogene Diversity and Taxonomy of Subtropical to Temperate Planktic Foraminifera across the Kuroshio Current Extension. Micropaleontology.

Lam, A. R., Stigall, A. L., Matzke, N. J. 2018. Dispersal in the Ordovician: Speciation patterns and paleobiogeographic analyses of brachiopods and trilobites. Palaeogeography, Palaeoclimatology, Palaeoecology 489, 147-165. doi: 10.1016/j.palaeo.2017.10.006

Stigall, A. L., Bauer, J. E., Lam, A. R., Wright, D. W. 2017. Biotic immigration events, speciation, and the accumulation of biodiversity in deep time. Global and Planetary Change 148, 242-257. doi: 10.1016/j.glopacha.2016.12.008

Lam, A. R., Stigall, A. L. 2015. Pathways and mechanisms of Late Ordovician (Cincinnatian) faunal migrations of Laurentia and Baltica. Estonian Journal of Earth Sciences 64 (1), 62-67. doi: 10.3176/earth.2015.11 Supplemental Materials

Abstracts Related to Paleobiogeography

Lam, A. R., Sheffield, S. L., and Matzke, N. J., 2020. Paleobiogeography of the early Paleozoic echinoderms across the Great Ordovician Biodiversification Event. Northeast/Southeast GSA Meeting, Reston, VA. (Conference canceled)

Sheffield, S., Lam, A.R., and Matzke, N. J., 2019. A global biogeographical analysis of Blastozoan echinoderms across the Great Ordovician Biodiversification Event. GSA Annual Meeting, Phoenix, AZ.

Lam, A. R., Leckie, R. M., and Crundwell, M. P., 2019. Paleobiogeography of the Neogene planktic foraminiferal genus Globoconella to interpret long-distance dispersal mechanisms. North American Paleontological Convention, Riverside, California.

Bryant, R., Lam, A. R., Leckie, R. M., Elderback, K., Lowery, C., Parker, A. 2018. Environmental distribution of foraminiferal morphotypes through the onset of OAE2 in the Western Interior Seaway. FORAMS 2018 Conference, Edinburgh, Scotland.

Stigall, A. L., Lam, A. R., Wright, D., Bauer, J. B., 2018. How is biodiversity produced? Biotic immigration events, speciation, and the accumulation of biodiversity in the fossil record. International Paleontological Conference.

Lam, A. R., Matzke, N., Stigall, A. L. 2016. Testing Dispersal of Benthic Invertebrates during the Richmondian Invasion using Bayesian and Maximum-Likelihood Analyses. IGCP 591 Annual Meeting, Ghent, Belgium.

Stigall, A. L., Lam, A. R., Wright, D. F., Bauer, J. E. 2016. Biotic immigration events, speciation, and the accumulation of biodiversity in the fossil record. Geological Society of America Abstracts with Programs, 48 (7). Online

Lam, A. R., Stigall, A. L. 2015. Biogeographic origins and dispersal pathways of invasive taxa: The Late Ordovician (Katian) Richmondian Invasion, Cincinnati area, Ohio. 12th International Symposium on the Ordovician System, Harrisonburg, Virginia, USA.

Stigall, A. L., Bauer, J. E., Brame, H.-M. R., Lam, A. R., Wright, D. F. 2015. Immigration, speciation, and biodiversity in Ordovician seas of Laurentia. 12th International Symposium on the Ordovician System, Harrisonburg, Virginia, USA.

Stigall, A. L., Wright, D. F., Lam, A. R., Bauer, J. E., 2015. Biotic immigration events, speciation, and biodiversity in Ordovician seas of Laurentia. Geological Society of America Abstracts with Programs, 47 (7). Online

Lam, A. R., Stigall, A. L. 2014. Parsimony Analysis of Endemicity of a Late Ordovician faunal migration: Identifying the invasion pathways and mechanisms of a regional invasion event. IGCP 591 Annual Meeting, Tartu, Estonia.

Lam, A. R., Stigall, A. L. 2014. Parsimony Analysis of Endemicity (PAE) of a Late Ordovician (Cincinnatian) faunal migration event: Where did invasive taxa originate, and how did they get to the Cincinnati basin? Geological Society of America Southeastern Section Program with Abstracts, 46 (3). Online