Biased extinction and evolutionary trends
The directionality of long-term trends can be strongly biased by forces intrinsic to a clade. Trends in body size and skeletal shape may be dictated more by variations in survivorship that reflect differences in ecology than by long-term directional changes in the environment. Hence, mass extinction...
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Cambridge University Press (CUP)
1991
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Online Access: | http://dx.doi.org/10.1017/s0094837300010721 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0094837300010721 |
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crcambridgeupr:10.1017/s0094837300010721 2024-09-15T18:30:57+00:00 Biased extinction and evolutionary trends Norris, Richard D. 1991 http://dx.doi.org/10.1017/s0094837300010721 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0094837300010721 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Paleobiology volume 17, issue 4, page 388-399 ISSN 0094-8373 1938-5331 journal-article 1991 crcambridgeupr https://doi.org/10.1017/s0094837300010721 2024-06-26T04:02:25Z The directionality of long-term trends can be strongly biased by forces intrinsic to a clade. Trends in body size and skeletal shape may be dictated more by variations in survivorship that reflect differences in ecology than by long-term directional changes in the environment. Hence, mass extinctions can help drive evolutionary trends by selectively eliminating some morphologies and permitting the survivors to found the next radiation. Examples include repeated trends toward larger maximum body size and the evolution of keeled species from those with globose tests in planktonic foraminifera. Both the trends in size and shape develop because small species with globose tests are significantly more resistant to extinction than species that are large or have peripheral keels. Hence, the survivors of both the Cretaceous-Tertiary and Eocene-Oligocene extinction episodes are small, unkeeled taxa. Large species and species with keels evolved convergently after both mass extinctions as the founders radiated anew. Comparison of three radiations of planktonic foraminifera suggest that the convergent evolution of similar test shapes and sizes is not due to synchronous changes in oceanography that track evolutionary trends. Instead, the reestablishment of habitat heterogeneity is needed to permit the ensuing radiation to unfold rather than to closely guide its progress. Similar evolutionary trends will develop in each radiation as long as the founders have similar morphology and the evolution of variants present in the previous radiation is not precluded by the environment. Article in Journal/Newspaper Planktonic foraminifera Cambridge University Press Paleobiology 17 4 388 399 |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
The directionality of long-term trends can be strongly biased by forces intrinsic to a clade. Trends in body size and skeletal shape may be dictated more by variations in survivorship that reflect differences in ecology than by long-term directional changes in the environment. Hence, mass extinctions can help drive evolutionary trends by selectively eliminating some morphologies and permitting the survivors to found the next radiation. Examples include repeated trends toward larger maximum body size and the evolution of keeled species from those with globose tests in planktonic foraminifera. Both the trends in size and shape develop because small species with globose tests are significantly more resistant to extinction than species that are large or have peripheral keels. Hence, the survivors of both the Cretaceous-Tertiary and Eocene-Oligocene extinction episodes are small, unkeeled taxa. Large species and species with keels evolved convergently after both mass extinctions as the founders radiated anew. Comparison of three radiations of planktonic foraminifera suggest that the convergent evolution of similar test shapes and sizes is not due to synchronous changes in oceanography that track evolutionary trends. Instead, the reestablishment of habitat heterogeneity is needed to permit the ensuing radiation to unfold rather than to closely guide its progress. Similar evolutionary trends will develop in each radiation as long as the founders have similar morphology and the evolution of variants present in the previous radiation is not precluded by the environment. |
format |
Article in Journal/Newspaper |
author |
Norris, Richard D. |
spellingShingle |
Norris, Richard D. Biased extinction and evolutionary trends |
author_facet |
Norris, Richard D. |
author_sort |
Norris, Richard D. |
title |
Biased extinction and evolutionary trends |
title_short |
Biased extinction and evolutionary trends |
title_full |
Biased extinction and evolutionary trends |
title_fullStr |
Biased extinction and evolutionary trends |
title_full_unstemmed |
Biased extinction and evolutionary trends |
title_sort |
biased extinction and evolutionary trends |
publisher |
Cambridge University Press (CUP) |
publishDate |
1991 |
url |
http://dx.doi.org/10.1017/s0094837300010721 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0094837300010721 |
genre |
Planktonic foraminifera |
genre_facet |
Planktonic foraminifera |
op_source |
Paleobiology volume 17, issue 4, page 388-399 ISSN 0094-8373 1938-5331 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0094837300010721 |
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Paleobiology |
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17 |
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4 |
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388 |
op_container_end_page |
399 |
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1810472500994244608 |