Sensitivity to species selection indicates the effect of nuisance variables on marine microfossil transfer functions
The species composition of many groups of marine plankton appears well predicted by sea surface temperature (SST). Consequently, fossil plankton assemblages have been widely used to reconstruct past SST. Most applications of this approach make use of the highest possible taxonomic resolution. Howeve...
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ftcopernicus:oai:publications.copernicus.org:cp70946 2023-05-15T18:00:45+02:00 Sensitivity to species selection indicates the effect of nuisance variables on marine microfossil transfer functions Jonkers, Lukas Kučera, Michal 2019-05-15 application/pdf https://doi.org/10.5194/cp-15-881-2019 https://cp.copernicus.org/articles/15/881/2019/ eng eng doi:10.5194/cp-15-881-2019 https://cp.copernicus.org/articles/15/881/2019/ eISSN: 1814-9332 Text 2019 ftcopernicus https://doi.org/10.5194/cp-15-881-2019 2020-07-20T16:22:50Z The species composition of many groups of marine plankton appears well predicted by sea surface temperature (SST). Consequently, fossil plankton assemblages have been widely used to reconstruct past SST. Most applications of this approach make use of the highest possible taxonomic resolution. However, not all species are sensitive to temperature, and their distribution may be governed by other parameters. There are thus reasons to question the merit of including information about all species, both for transfer function performance and for its effect on reconstructions. Here we investigate the effect of species selection on planktonic foraminifera transfer functions. We assess species importance for transfer function models using a random forest technique and evaluate the performance of models with an increasing number of species. Irrespective of using models that use the entire training set (weighted averaging) or models that use only a subset of the training set (modern analogue technique), we find that the majority of foraminifera species does not carry useful information for temperature reconstruction. Less than one-third of the species in the training set is required to provide a temperature estimate with a prediction error comparable to a transfer function that uses all species in the training set. However, species selection matters for paleotemperature estimates. We find that transfer function models with a different number of species but with the same error may yield different reconstructions of sea surface temperature when applied to the same fossil assemblages. This ambiguity in the reconstructions implies that fossil assemblage change reflects a combination of temperature and other environmental factors. The contribution of the additional factors is site and time specific, indicating ecological and geological complexity in the formation of the sedimentary assemblages. The possibility of obtaining multiple different reconstructions from a single sediment record presents a previously unrecognized source of uncertainty for sea surface temperature estimates based on planktonic foraminifera assemblages. This uncertainty can be evaluated by determining the sensitivity of the reconstructions to species pruning. Text Planktonic foraminifera Copernicus Publications: E-Journals Climate of the Past 15 3 881 891 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
description |
The species composition of many groups of marine plankton appears well predicted by sea surface temperature (SST). Consequently, fossil plankton assemblages have been widely used to reconstruct past SST. Most applications of this approach make use of the highest possible taxonomic resolution. However, not all species are sensitive to temperature, and their distribution may be governed by other parameters. There are thus reasons to question the merit of including information about all species, both for transfer function performance and for its effect on reconstructions. Here we investigate the effect of species selection on planktonic foraminifera transfer functions. We assess species importance for transfer function models using a random forest technique and evaluate the performance of models with an increasing number of species. Irrespective of using models that use the entire training set (weighted averaging) or models that use only a subset of the training set (modern analogue technique), we find that the majority of foraminifera species does not carry useful information for temperature reconstruction. Less than one-third of the species in the training set is required to provide a temperature estimate with a prediction error comparable to a transfer function that uses all species in the training set. However, species selection matters for paleotemperature estimates. We find that transfer function models with a different number of species but with the same error may yield different reconstructions of sea surface temperature when applied to the same fossil assemblages. This ambiguity in the reconstructions implies that fossil assemblage change reflects a combination of temperature and other environmental factors. The contribution of the additional factors is site and time specific, indicating ecological and geological complexity in the formation of the sedimentary assemblages. The possibility of obtaining multiple different reconstructions from a single sediment record presents a previously unrecognized source of uncertainty for sea surface temperature estimates based on planktonic foraminifera assemblages. This uncertainty can be evaluated by determining the sensitivity of the reconstructions to species pruning. |
format |
Text |
author |
Jonkers, Lukas Kučera, Michal |
spellingShingle |
Jonkers, Lukas Kučera, Michal Sensitivity to species selection indicates the effect of nuisance variables on marine microfossil transfer functions |
author_facet |
Jonkers, Lukas Kučera, Michal |
author_sort |
Jonkers, Lukas |
title |
Sensitivity to species selection indicates the effect of nuisance variables on marine microfossil transfer functions |
title_short |
Sensitivity to species selection indicates the effect of nuisance variables on marine microfossil transfer functions |
title_full |
Sensitivity to species selection indicates the effect of nuisance variables on marine microfossil transfer functions |
title_fullStr |
Sensitivity to species selection indicates the effect of nuisance variables on marine microfossil transfer functions |
title_full_unstemmed |
Sensitivity to species selection indicates the effect of nuisance variables on marine microfossil transfer functions |
title_sort |
sensitivity to species selection indicates the effect of nuisance variables on marine microfossil transfer functions |
publishDate |
2019 |
url |
https://doi.org/10.5194/cp-15-881-2019 https://cp.copernicus.org/articles/15/881/2019/ |
genre |
Planktonic foraminifera |
genre_facet |
Planktonic foraminifera |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-15-881-2019 https://cp.copernicus.org/articles/15/881/2019/ |
op_doi |
https://doi.org/10.5194/cp-15-881-2019 |
container_title |
Climate of the Past |
container_volume |
15 |
container_issue |
3 |
container_start_page |
881 |
op_container_end_page |
891 |
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1766169975515512832 |