The multi-peak adaptive landscape of crocodylomorph body size evolution
Abstract Background Little is known about the long-term patterns of body size evolution in Crocodylomorpha, the > 200-million-year-old group that includes living crocodylians and their extinct relatives. Extant crocodylians are mostly large-bodied (3–7 m) predators. However, extinct crocodylomorp...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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BMC
2019-08-01
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| Series: | BMC Evolutionary Biology |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s12862-019-1466-4 |
| _version_ | 1819130008253235200 |
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| author | Pedro L. Godoy Roger B. J. Benson Mario Bronzati Richard J. Butler |
| author_facet | Pedro L. Godoy Roger B. J. Benson Mario Bronzati Richard J. Butler |
| author_sort | Pedro L. Godoy |
| collection | DOAJ |
| description | Abstract Background Little is known about the long-term patterns of body size evolution in Crocodylomorpha, the > 200-million-year-old group that includes living crocodylians and their extinct relatives. Extant crocodylians are mostly large-bodied (3–7 m) predators. However, extinct crocodylomorphs exhibit a wider range of phenotypes, and many of the earliest taxa were much smaller (< 1.2 m). This suggests a pattern of size increase through time that could be caused by multi-lineage evolutionary trends of size increase or by selective extinction of small-bodied species. Here, we characterise patterns of crocodylomorph body size evolution using a model fitting-approach (with cranial measurements serving as proxies). We also estimate body size disparity through time and quantitatively test hypotheses of biotic and abiotic factors as potential drivers of crocodylomorph body size evolution. Results Crocodylomorphs reached an early peak in body size disparity during the Late Jurassic, and underwent an essentially continual decline since then. A multi-peak Ornstein-Uhlenbeck model outperforms all other evolutionary models fitted to our data (including both uniform and non-uniform), indicating that the macroevolutionary dynamics of crocodylomorph body size are better described within the concept of an adaptive landscape, with most body size variation emerging after shifts to new macroevolutionary regimes (analogous to adaptive zones). We did not find support for a consistent evolutionary trend towards larger sizes among lineages (i.e., Cope’s rule), or strong correlations of body size with climate. Instead, the intermediate to large body sizes of some crocodylomorphs are better explained by group-specific adaptations. In particular, the evolution of a more aquatic lifestyle (especially marine) correlates with increases in average body size, though not without exceptions. Conclusions Shifts between macroevolutionary regimes provide a better explanation of crocodylomorph body size evolution on large phylogenetic and temporal scales, suggesting a central role for lineage-specific adaptations rather than climatic forcing. Shifts leading to larger body sizes occurred in most aquatic and semi-aquatic groups. This, combined with extinctions of groups occupying smaller body size regimes (particularly during the Late Cretaceous and Cenozoic), gave rise to the upward-shifted body size distribution of extant crocodylomorphs compared to their smaller-bodied terrestrial ancestors. |
| first_indexed | 2024-12-22T08:52:47Z |
| format | Article |
| id | doaj.art-81f399d1a0dc472081e0c756cf074b51 |
| institution | Directory Open Access Journal |
| issn | 1471-2148 |
| language | English |
| last_indexed | 2024-12-22T08:52:47Z |
| publishDate | 2019-08-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Evolutionary Biology |
| spelling | doaj.art-81f399d1a0dc472081e0c756cf074b512022-12-21T18:31:55ZengBMCBMC Evolutionary Biology1471-21482019-08-0119112910.1186/s12862-019-1466-4The multi-peak adaptive landscape of crocodylomorph body size evolutionPedro L. Godoy0Roger B. J. Benson1Mario Bronzati2Richard J. Butler3School of Geography, Earth and Environmental Sciences, University of BirminghamDepartment of Earth Sciences, University of OxfordLaboratório de Paleontologia de Ribeirão Preto, FFCLRP, Universidade de São PauloSchool of Geography, Earth and Environmental Sciences, University of BirminghamAbstract Background Little is known about the long-term patterns of body size evolution in Crocodylomorpha, the > 200-million-year-old group that includes living crocodylians and their extinct relatives. Extant crocodylians are mostly large-bodied (3–7 m) predators. However, extinct crocodylomorphs exhibit a wider range of phenotypes, and many of the earliest taxa were much smaller (< 1.2 m). This suggests a pattern of size increase through time that could be caused by multi-lineage evolutionary trends of size increase or by selective extinction of small-bodied species. Here, we characterise patterns of crocodylomorph body size evolution using a model fitting-approach (with cranial measurements serving as proxies). We also estimate body size disparity through time and quantitatively test hypotheses of biotic and abiotic factors as potential drivers of crocodylomorph body size evolution. Results Crocodylomorphs reached an early peak in body size disparity during the Late Jurassic, and underwent an essentially continual decline since then. A multi-peak Ornstein-Uhlenbeck model outperforms all other evolutionary models fitted to our data (including both uniform and non-uniform), indicating that the macroevolutionary dynamics of crocodylomorph body size are better described within the concept of an adaptive landscape, with most body size variation emerging after shifts to new macroevolutionary regimes (analogous to adaptive zones). We did not find support for a consistent evolutionary trend towards larger sizes among lineages (i.e., Cope’s rule), or strong correlations of body size with climate. Instead, the intermediate to large body sizes of some crocodylomorphs are better explained by group-specific adaptations. In particular, the evolution of a more aquatic lifestyle (especially marine) correlates with increases in average body size, though not without exceptions. Conclusions Shifts between macroevolutionary regimes provide a better explanation of crocodylomorph body size evolution on large phylogenetic and temporal scales, suggesting a central role for lineage-specific adaptations rather than climatic forcing. Shifts leading to larger body sizes occurred in most aquatic and semi-aquatic groups. This, combined with extinctions of groups occupying smaller body size regimes (particularly during the Late Cretaceous and Cenozoic), gave rise to the upward-shifted body size distribution of extant crocodylomorphs compared to their smaller-bodied terrestrial ancestors.http://link.springer.com/article/10.1186/s12862-019-1466-4CrocodylomorphaCrocodyliformesBody size evolutionAdaptive landscapePhylogenetic comparative methodsOrnstein–Uhlenbeck models |
| spellingShingle | Pedro L. Godoy Roger B. J. Benson Mario Bronzati Richard J. Butler The multi-peak adaptive landscape of crocodylomorph body size evolution BMC Evolutionary Biology Crocodylomorpha Crocodyliformes Body size evolution Adaptive landscape Phylogenetic comparative methods Ornstein–Uhlenbeck models |
| title | The multi-peak adaptive landscape of crocodylomorph body size evolution |
| title_full | The multi-peak adaptive landscape of crocodylomorph body size evolution |
| title_fullStr | The multi-peak adaptive landscape of crocodylomorph body size evolution |
| title_full_unstemmed | The multi-peak adaptive landscape of crocodylomorph body size evolution |
| title_short | The multi-peak adaptive landscape of crocodylomorph body size evolution |
| title_sort | multi peak adaptive landscape of crocodylomorph body size evolution |
| topic | Crocodylomorpha Crocodyliformes Body size evolution Adaptive landscape Phylogenetic comparative methods Ornstein–Uhlenbeck models |
| url | http://link.springer.com/article/10.1186/s12862-019-1466-4 |
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