Proceedings Chapter
Reference
Extinctions in the marine plankton preceded by stabilizing selection
WEINKAUF, Manuel, et al.
WEINKAUF, Manuel, et al . Extinctions in the marine plankton preceded by stabilizing selection.
In: Spezzaferri, Silvia ; Langer, Martin & Rettori, Roberto. From Normal Marine to Extreme Environments: A Micropalaeontological Perspective - The Micropalaeontological Society's Joint Foramainifera and Nannofossil Meeting . 2019. p. 57
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Extinctions in the marine plankton preceded by stabilizing selection Manuel F. G. Weinkauf1,2,3, Fabian G. W. Bonitz1,a, Rossana Martini3, and Michal
Kučera1,2
1Department of Geosciences, Eberhard–Karls Universität Tübingen, Tübingen, Germany
2Center for Marine Environmental Sciences (MARUM), Universität Bremen, Bremen, Germany
3Department of Earth Sciences, Université de Genève, Genève, Switzerland
aCurrent Address: Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway
Corresponding author e-mail: [email protected]
Populations facing persistent stress are threatened by extinction unless they adapt by either disruption or stabilization. Stabilization is more economical, because it quickly transfers a large part of the population closer to a new ecological optimum. However, canalization is deleterious in the face of persistently increasing stress, because it reduces variability and the populations’ ability to react to further changes.
Understanding how natural populations react to intensifying stress reaching terminal levels is key to assessing their resilience to environmental change such as that caused by global warming. Here, we make use of the glacial salinity rise in the Red Sea as a natural experiment allowing us to analyse the reaction of planktonic Foraminifera to stress escalation in the geological past. We analyse morphological trait state and variation in two species across a salinity rise leading to their local extinction. One species reacted by stabilization, detectable several thousand years prior to extinction.
The second species reacted by trait divergence, but each of the two divergent populations remained stable or reacted by further stabilization. These observations indicate that the default reaction of the studied Foraminifera is canalization, and that stress escalation did not lead to the emergence of adapted forms. An inherent inability to breach the global adaptive threshold would explain why communities of Foraminifera reacted to Quaternary climate change by tracking their zonally shifting environments and means that plankton populations adapted to response by migration will be at risk of extinction when exposed to stress outside of their adaptive range.
