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Evolutionary tradeoffs, Pareto optimality and the morphology of ammonite shells.

Tendler A, Mayo A, Alon U - BMC Syst Biol (2015)

Bottom Line: After mass extinctions, surviving species evolve to refill essentially the same pyramid, suggesting that the tasks are unchanging.We infer putative tasks for each archetype, related to economy of shell material, rapid shell growth, hydrodynamics and compactness.These results support Pareto optimality theory as an approach to study evolutionary tradeoffs, and demonstrate how this approach can be used to infer the putative tasks that may shape the natural selection of phenotypes.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular cell biology, Weizmann Institute of Science, Rehovot, 76100, Israel. tendlea@gmail.com.

ABSTRACT

Background: Organisms that need to perform multiple tasks face a fundamental tradeoff: no design can be optimal at all tasks at once. Recent theory based on Pareto optimality showed that such tradeoffs lead to a highly defined range of phenotypes, which lie in low-dimensional polyhedra in the space of traits. The vertices of these polyhedra are called archetypes- the phenotypes that are optimal at a single task. To rigorously test this theory requires measurements of thousands of species over hundreds of millions of years of evolution. Ammonoid fossil shells provide an excellent model system for this purpose. Ammonoids have a well-defined geometry that can be parameterized using three dimensionless features of their logarithmic-spiral-shaped shells. Their evolutionary history includes repeated mass extinctions.

Results: We find that ammonoids fill out a pyramid in morphospace, suggesting five specific tasks - one for each vertex of the pyramid. After mass extinctions, surviving species evolve to refill essentially the same pyramid, suggesting that the tasks are unchanging. We infer putative tasks for each archetype, related to economy of shell material, rapid shell growth, hydrodynamics and compactness.

Conclusions: These results support Pareto optimality theory as an approach to study evolutionary tradeoffs, and demonstrate how this approach can be used to infer the putative tasks that may shape the natural selection of phenotypes.

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Related in: MedlinePlus

Size is enriched at some of the archetypes. Ammonoid shell diameter as a function of distance from each archetype shows that small diameters are prevalent near archetypes 4 and 5. Data includes diameter for 392 genera (green points) [29], divided into 10 bins with equal number of genera according to the distance from each archetype. Average diameter for each bin is plotted (blue points). For convenience, a fit of the averages to a line is shown. (A) No diameter enrichment near archetype 1 (p = 0.29). (B) Positive diameter enrichment near archetype 2 (p <10-4) (C) Positive diameter enrichment near archetype 3 (p = 0.0007). (D) Negative diameter enrichment near archetype 4 (p <10-4) (E) Negative diameter enrichment near archetype 5 (p = 0.0002).
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Fig6: Size is enriched at some of the archetypes. Ammonoid shell diameter as a function of distance from each archetype shows that small diameters are prevalent near archetypes 4 and 5. Data includes diameter for 392 genera (green points) [29], divided into 10 bins with equal number of genera according to the distance from each archetype. Average diameter for each bin is plotted (blue points). For convenience, a fit of the averages to a line is shown. (A) No diameter enrichment near archetype 1 (p = 0.29). (B) Positive diameter enrichment near archetype 2 (p <10-4) (C) Positive diameter enrichment near archetype 3 (p = 0.0007). (D) Negative diameter enrichment near archetype 4 (p <10-4) (E) Negative diameter enrichment near archetype 5 (p = 0.0002).

Mentions: One feature of globular ammonoids is small size for a given internal volume, because spherical shapes have the minimal diameter of all shapes with the same volume. Up to now, we did not consider the absolute size of the ammonoids, only on dimensionless shape traits W, D and S. To address this, we correlated data by McGowan [29] on ammonoid size (diameter) with distance from the five vertices of the pyramid. We find an enrichment of small ammonoids most strongly near archetypes 4 and 5: the genera nearest to these vertices have the smallest diameters (Figure 6). Archetypes 2 and 3 are enriched with large ammonoids and archetype 1 has weak enrichment since its S value (which is related to globularity, Additional file 1) is relatively larger than archetypes 2 and 3 (Table 1). Archetypes 4 and 5 may thus correspond to economy and hydrodynamic tasks respectively, combined with a need for smallness. This relation between diameter and globularity is in line also with [55], which used a different dataset.Figure 7


Evolutionary tradeoffs, Pareto optimality and the morphology of ammonite shells.

Tendler A, Mayo A, Alon U - BMC Syst Biol (2015)

Size is enriched at some of the archetypes. Ammonoid shell diameter as a function of distance from each archetype shows that small diameters are prevalent near archetypes 4 and 5. Data includes diameter for 392 genera (green points) [29], divided into 10 bins with equal number of genera according to the distance from each archetype. Average diameter for each bin is plotted (blue points). For convenience, a fit of the averages to a line is shown. (A) No diameter enrichment near archetype 1 (p = 0.29). (B) Positive diameter enrichment near archetype 2 (p <10-4) (C) Positive diameter enrichment near archetype 3 (p = 0.0007). (D) Negative diameter enrichment near archetype 4 (p <10-4) (E) Negative diameter enrichment near archetype 5 (p = 0.0002).
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4404009&req=5

Fig6: Size is enriched at some of the archetypes. Ammonoid shell diameter as a function of distance from each archetype shows that small diameters are prevalent near archetypes 4 and 5. Data includes diameter for 392 genera (green points) [29], divided into 10 bins with equal number of genera according to the distance from each archetype. Average diameter for each bin is plotted (blue points). For convenience, a fit of the averages to a line is shown. (A) No diameter enrichment near archetype 1 (p = 0.29). (B) Positive diameter enrichment near archetype 2 (p <10-4) (C) Positive diameter enrichment near archetype 3 (p = 0.0007). (D) Negative diameter enrichment near archetype 4 (p <10-4) (E) Negative diameter enrichment near archetype 5 (p = 0.0002).
Mentions: One feature of globular ammonoids is small size for a given internal volume, because spherical shapes have the minimal diameter of all shapes with the same volume. Up to now, we did not consider the absolute size of the ammonoids, only on dimensionless shape traits W, D and S. To address this, we correlated data by McGowan [29] on ammonoid size (diameter) with distance from the five vertices of the pyramid. We find an enrichment of small ammonoids most strongly near archetypes 4 and 5: the genera nearest to these vertices have the smallest diameters (Figure 6). Archetypes 2 and 3 are enriched with large ammonoids and archetype 1 has weak enrichment since its S value (which is related to globularity, Additional file 1) is relatively larger than archetypes 2 and 3 (Table 1). Archetypes 4 and 5 may thus correspond to economy and hydrodynamic tasks respectively, combined with a need for smallness. This relation between diameter and globularity is in line also with [55], which used a different dataset.Figure 7

Bottom Line: After mass extinctions, surviving species evolve to refill essentially the same pyramid, suggesting that the tasks are unchanging.We infer putative tasks for each archetype, related to economy of shell material, rapid shell growth, hydrodynamics and compactness.These results support Pareto optimality theory as an approach to study evolutionary tradeoffs, and demonstrate how this approach can be used to infer the putative tasks that may shape the natural selection of phenotypes.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular cell biology, Weizmann Institute of Science, Rehovot, 76100, Israel. tendlea@gmail.com.

ABSTRACT

Background: Organisms that need to perform multiple tasks face a fundamental tradeoff: no design can be optimal at all tasks at once. Recent theory based on Pareto optimality showed that such tradeoffs lead to a highly defined range of phenotypes, which lie in low-dimensional polyhedra in the space of traits. The vertices of these polyhedra are called archetypes- the phenotypes that are optimal at a single task. To rigorously test this theory requires measurements of thousands of species over hundreds of millions of years of evolution. Ammonoid fossil shells provide an excellent model system for this purpose. Ammonoids have a well-defined geometry that can be parameterized using three dimensionless features of their logarithmic-spiral-shaped shells. Their evolutionary history includes repeated mass extinctions.

Results: We find that ammonoids fill out a pyramid in morphospace, suggesting five specific tasks - one for each vertex of the pyramid. After mass extinctions, surviving species evolve to refill essentially the same pyramid, suggesting that the tasks are unchanging. We infer putative tasks for each archetype, related to economy of shell material, rapid shell growth, hydrodynamics and compactness.

Conclusions: These results support Pareto optimality theory as an approach to study evolutionary tradeoffs, and demonstrate how this approach can be used to infer the putative tasks that may shape the natural selection of phenotypes.

Show MeSH
Related in: MedlinePlus