Differences between evolution of mean form and evolution of new morphotypes: an example from Late Cretaceous planktonic foraminifera
Morphological evolution in the Late Cretaceous (Maastrichtian) Contusotruncana lineage of planktonic foraminifera was studied at DSDP Sites 525 (South Atlantic) and 384 (North Atlantic). A multivariable approach was used to separate aspects of form controlled by geographical variation (size, spiral...
Published in: | Paleobiology |
---|---|
Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Cambridge University Press (CUP)
1998
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1017/s0094837300019965 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0094837300019965 |
id |
crcambridgeupr:10.1017/s0094837300019965 |
---|---|
record_format |
openpolar |
spelling |
crcambridgeupr:10.1017/s0094837300019965 2024-05-12T08:08:09+00:00 Differences between evolution of mean form and evolution of new morphotypes: an example from Late Cretaceous planktonic foraminifera Kucera, Michal Malmgren, Björn A. 1998 http://dx.doi.org/10.1017/s0094837300019965 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0094837300019965 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Paleobiology volume 24, issue 1, page 49-63 ISSN 0094-8373 1938-5331 Paleontology General Agricultural and Biological Sciences Ecology Ecology, Evolution, Behavior and Systematics journal-article 1998 crcambridgeupr https://doi.org/10.1017/s0094837300019965 2024-04-18T06:54:01Z Morphological evolution in the Late Cretaceous (Maastrichtian) Contusotruncana lineage of planktonic foraminifera was studied at DSDP Sites 525 (South Atlantic) and 384 (North Atlantic). A multivariable approach was used to separate aspects of form controlled by geographical variation (size, spiral roundness of the test, percentage of kummerform specimens) from those due to changes that occurred simultaneously in geographically distant populations of the lineage (shell conicity, number of chambers in the last whorl). A gradual increase in mean shell conicity was observed over the last 3 million years of the Cretaceous. It arose from the combination of a rapid development of highly conical shells after 68.5 Ma and a long-term trend of progressive disappearance of the ancestral morphotype. Therefore, despite the gradual change in “mean form,” the morphological evolution in the Contusotruncana lineage differs from the classical image of phyletic gradualism. The gradual increase in mean shell conicity in the lineage was accompanied by a remarkable decrease in its absolute abundance (shell accumulation rate), suggesting that the changes in shell morphology might not have been neutral with respect to natural selection. Apparently, gradual change in “mean form” of fossil lineages does not require an equally gradual development of morphological novelties. It may be caused by natural selection operating on a constant range of variation in populations living in environments without geographical barriers. Article in Journal/Newspaper North Atlantic Planktonic foraminifera Cambridge University Press Paleobiology 24 1 49 63 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Paleontology General Agricultural and Biological Sciences Ecology Ecology, Evolution, Behavior and Systematics |
spellingShingle |
Paleontology General Agricultural and Biological Sciences Ecology Ecology, Evolution, Behavior and Systematics Kucera, Michal Malmgren, Björn A. Differences between evolution of mean form and evolution of new morphotypes: an example from Late Cretaceous planktonic foraminifera |
topic_facet |
Paleontology General Agricultural and Biological Sciences Ecology Ecology, Evolution, Behavior and Systematics |
description |
Morphological evolution in the Late Cretaceous (Maastrichtian) Contusotruncana lineage of planktonic foraminifera was studied at DSDP Sites 525 (South Atlantic) and 384 (North Atlantic). A multivariable approach was used to separate aspects of form controlled by geographical variation (size, spiral roundness of the test, percentage of kummerform specimens) from those due to changes that occurred simultaneously in geographically distant populations of the lineage (shell conicity, number of chambers in the last whorl). A gradual increase in mean shell conicity was observed over the last 3 million years of the Cretaceous. It arose from the combination of a rapid development of highly conical shells after 68.5 Ma and a long-term trend of progressive disappearance of the ancestral morphotype. Therefore, despite the gradual change in “mean form,” the morphological evolution in the Contusotruncana lineage differs from the classical image of phyletic gradualism. The gradual increase in mean shell conicity in the lineage was accompanied by a remarkable decrease in its absolute abundance (shell accumulation rate), suggesting that the changes in shell morphology might not have been neutral with respect to natural selection. Apparently, gradual change in “mean form” of fossil lineages does not require an equally gradual development of morphological novelties. It may be caused by natural selection operating on a constant range of variation in populations living in environments without geographical barriers. |
format |
Article in Journal/Newspaper |
author |
Kucera, Michal Malmgren, Björn A. |
author_facet |
Kucera, Michal Malmgren, Björn A. |
author_sort |
Kucera, Michal |
title |
Differences between evolution of mean form and evolution of new morphotypes: an example from Late Cretaceous planktonic foraminifera |
title_short |
Differences between evolution of mean form and evolution of new morphotypes: an example from Late Cretaceous planktonic foraminifera |
title_full |
Differences between evolution of mean form and evolution of new morphotypes: an example from Late Cretaceous planktonic foraminifera |
title_fullStr |
Differences between evolution of mean form and evolution of new morphotypes: an example from Late Cretaceous planktonic foraminifera |
title_full_unstemmed |
Differences between evolution of mean form and evolution of new morphotypes: an example from Late Cretaceous planktonic foraminifera |
title_sort |
differences between evolution of mean form and evolution of new morphotypes: an example from late cretaceous planktonic foraminifera |
publisher |
Cambridge University Press (CUP) |
publishDate |
1998 |
url |
http://dx.doi.org/10.1017/s0094837300019965 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0094837300019965 |
genre |
North Atlantic Planktonic foraminifera |
genre_facet |
North Atlantic Planktonic foraminifera |
op_source |
Paleobiology volume 24, issue 1, page 49-63 ISSN 0094-8373 1938-5331 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0094837300019965 |
container_title |
Paleobiology |
container_volume |
24 |
container_issue |
1 |
container_start_page |
49 |
op_container_end_page |
63 |
_version_ |
1798851058606276608 |