Evolutionary prospection in the Neogene planktic foraminifer Globorotalia menardii and related forms from ODP Hole 925B (Ceara Rise, western tropical Atlantic): evidence for gradual evolution superimposed by long distance dispersal?

Knappertsbusch, Michael

doi:10.1007/s13358-016-0113-6

Cited by 13 publications

(38 citation statements)

References 151 publications

(255 reference statements)

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“…This study focuses on the test-size parameter X, Y and Ar. In order to compare 150 specimens with dextral and sinistral coiling, dextral specimens were vertically mirrored using the adapted "DexFlip_win" program, modified from Knappertsbusch (2016). https://doi.org/10.5194/bg-2021-67 Preprint.…”

Section: Sample Preparation and Parameter Measurementmentioning

confidence: 99%

“…The identification of menardiform specimens is based on illustrations in Kennett and Srinivasan (1983), Bolli et al (1985) and comparison with the reference collection to "49 Cenozoic planktonic foraminiferal zones and subzones prepared by Bolli in 1985Bolli in -1987, which is deposited at the Natural History εuseum Basel. Knappertsbusch (2016) refers to the disappearance of G. limbata as a possible pseudoextinction because of the occurrence of singular specimens of menardiforms with seven chambers in the last whorl after 2.39 Ma. with seven chambers are accounted as G. limbata, a form which became extinct during the early Pleistocene.…”

Section: Globorotalia Menardii Lineage -Species Discriminationmentioning

confidence: 99%

“…No smoothing of frequencies was applied, because experiments revealed an increasing loss of frequency variation with increasing size of bin-width. However, in contrast to Knappertsbusch and Mary (2012) and Knappertsbusch (2016), local absolute specimen frequencies were used throughout instead of relative frequencies.…”

Section: Univariate and Contoured Frequency Diagramsmentioning

confidence: 99%

“…The present study documents the associated morphological changes. Particularly, it investigates, if the pronounced test-size increase of G. menardii observed in the Caribbean Sea (Knappertsbusch, 2007) and the western tropical Atlantic Ocean (WTAO; (Knappertsbusch, 2016) in the early Pleistocene occurs also in the eastern tropical Atlantic Ocean (ETAO). And if so, it seeks for new insight for the underlying evolutionary processes.…”

Section: Introductionmentioning

confidence: 99%

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Test-Size Evolution of the planktonic Foraminifera <i>Globorotalia menardii</i> in the Eastern Tropical Atlantic since the Late Miocene

Friesenhagen

2021

Preprint

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Abstract. The mean test size of planktonic foraminifera (PF) is known to have increased especially during the last 12 Ma, probably in terms of an adaptive response to an intensification of the surface-water stratification. On geologically short timescales, the test size in PF is related to environmental conditions. In an optimal species-specific environment, individuals exhibit a greater maximum and average test size, while the size decreases the more unfavourable the environment becomes. An interesting case was observed in the late Neogene and Quaternary size evolution of Globorotalia menardii, which seems to be too extreme to be only explained by changes in environmental conditions. In the western tropical Atlantic Ocean (WTAO) and the Caribbean Sea, the test size more than doubles from 2.6 Ma to 1.95 Ma and 1.7 Ma, respectively, following an almost uninterrupted and successive phase of test size decrease from 4 Ma. Two hypotheses have been suggested to explain the sudden occurrence of a giant G. menardii form: it was triggered by either (1) a punctuated, regional evolutionary event or (2) the immigration of specimens from the Indian Ocean via the Agulhas Leakage. Morphometric measurements of tests from sediment samples of the Ocean Drilling Program (ODP) Leg 108 Hole 667A in the eastern tropical Atlantic Ocean (ETAO), show that the giant type already appears 0.1 Ma earlier at this location than in the WTAO, which indicates that the extreme size increase in the early Pleistocene was a tropical-Atlantic-Ocean-wide event. A coinciding change in the predominant coiling direction suggests that probably a new morphotype occurred. If the giant size and the uniform change in the predominant coiling direction are an indicator for this new type, the form already occurred in the eastern tropical Pacific Ocean at the Pliocene/Pleistocene boundary at 2.58 Ma. This finding supports the Agulhas Leakage hypothesis. However, the hypothesis of a regional, punctuated evolutionary event cannot be dismissed due to missing data from the Indian Ocean. This paper presents the AMOC/thermocline hypothesis, which not only suggests an alternative explanation for the sudden test-size increase in the early Pleistocene, but also for the test size evolution within the whole tropical Atlantic Ocean and the Caribbean Sea for the last 8 Ma. The test-size evolution shows a similar trend with indicators for changes in the Atlantic Meridional Overturning Circulation (AMOC) strength. The mechanism behind that might be that changes in the AMOC strength have a major influence on the thermal stratification of the upper water column, which is known to be the habitat of G. menardii.

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Section: Sample Preparation and Parameter Measurementmentioning

confidence: 99%

Section: Globorotalia Menardii Lineage -Species Discriminationmentioning

confidence: 99%

Section: Univariate and Contoured Frequency Diagramsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Test-Size Evolution of the planktonic Foraminifera <i>Globorotalia menardii</i> in the Eastern Tropical Atlantic since the Late Miocene

Friesenhagen

2021

Preprint

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“…Understanding the morphological reaction of Foraminifera toward environmental stress could serve as a proxy for environmental reconstructions and further our understanding of evolvability of this organismal group. Past studies have shown that morphological deviations in benthic and planktonic Foraminifera can be caused by environmental forcing (Malmgren and Kennett 1976, Malmgren 1984, Baumfalk et al 1987, Mary and Knappertsbusch 2013, Moller et al 2013, Weinkauf et al 2014, Knappertsbusch 2016, Brombacher et al 2017. But since these studies quantified morphology in very different ways, the results obtained are scarce and controversial.…”

Section: Introductionmentioning

confidence: 99%

Extinctions in marine plankton preceded by stabilizing selection

Weinkauf

Bonitz

Martini

et al. 2019

Preprint

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Unless they adapt, populations facing persistent stress are threatened by extinction. Theoretically, populations facing stress can react by either disruption, increasing trait variation, or stabilisation, decreasing trait variation. In the short term, the more economical response is stabilisation, because it quickly transfers a large part of the population closer to a new ecological optimum. However, canalisation is deleterious in the face of persistently increasing stress because it reduces variability and thus decreases the ability to react to further change in stress. 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. Because extinctions are hard to predict, observational data on the adaptive reaction of populations facing extinction are rare. In this study, 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 variance in two species across a salinity rise leading to their local extinction. One species reacted by stabilisation in shape and size, detectable several thousand years prior to extinction. The second species reacted by trait divergence, but each of the two divergent populations remains stable or reacted by further stabilisation. These observations indicate that the default reaction of the studied Foraminifera is stabilisation and that stress escalation did not lead to the local emergence of adapted forms. Inability to breach the global adaptive threshold would explain why communities of Foraminifera, and many other groups of marine plankton, reacted to Quaternary climate change by faithfully tracking their zonally shifting environments. It also means that populations of marine species adapted to response by migration, when exposed to stress outside of the adaptive range, will be at risk of extinction.

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