98-4 Changing Deep-Sea Latitudinal Diversity Gradients in Benthic Foraminifera across the Cenozoic

Session: Linking Biodiversity Loss to Environmental Stressors Through Integrated Approaches

Presenting Author:

Authors:

Abstract:

The Latitudinal Diversity Gradient (LDG) is one of the most recognizable large-scale patterns in biogeography where, despite notable exceptions, the number of unique species is highest at low latitudes and decreases poleward. Research on the LDG provides crucial insights into how environmental and evolutionary factors influence species distribution and ecosystem structure. However, previous work studying both modern and paleo- marine LDGs have predominantly focused on sea-surface and continental shelf environments. Benthic foraminifera, and their fossil remains, can be found in abundance across all ocean depths, allowing us to study the development of LDGs in the deep-sea through time.

Previous research in shallow-water settings indicates that the slope of the LDG changes with climate during the Cenozoic, in which hothouse worlds have a shallower gradient from equator-to-pole and icehouse worlds have a steeper gradient. Here I test the hypothesis that LDGs in the deep sea also vary with climate using a global compilation of benthic foraminiferal census records ranging from the Late Cretaceous to the present day. Preliminary results show strengthening in global taxonomic LDGs across the Eocene-Oligocene boundary that continues through the Miocene. Dissecting the Miocene into five smaller time bins related to major changes in climate states reveals a LDG similar to the LDG of modern benthic foraminifera in the first four Miocene time bins. The LDG inverts slightly during in the latest Miocene time bin when there was enhanced productivity. Additionally, benthic foraminiferal morphology is linked to environmental and ecological factors such as oxygenation and trophic conditions, allowing us to test for deep-sea LDGs in ecological function. Ongoing work will include analyses of morphogroups to test whether taxonomic and functional gradients are consistent. Studying how the modern deep-sea LDG developed in response to changing climates will allow us to better understand how species diversity and distribution might change in the future due to anthropogenic pressures.

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

doi: 10.1130/abs/2025AM-7204

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