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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

The performance contours of the three putative tasks for ammonoid shells. (A) Contours for shell economy, defined as the ratio of internal volume to shell volume, with red denoting high values, and blue low values. For gyroconic shells (non-overlapping whorls), this performance function becomes constant, and equal to the lowest contour shown (deep blue). The triangle encapsulating the entire ammonoid dataset is shown in black. (B) Contours for the drag coefficient measured by Chamberlain [36], red lines denote lower drag or better hydrodynamics. (C) Contours for the growth function defined in the main text, red lines denote quicker growth. (D) The contours of the three tasks give rise to a suite of variation denoted by blue points.
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Fig4: The performance contours of the three putative tasks for ammonoid shells. (A) Contours for shell economy, defined as the ratio of internal volume to shell volume, with red denoting high values, and blue low values. For gyroconic shells (non-overlapping whorls), this performance function becomes constant, and equal to the lowest contour shown (deep blue). The triangle encapsulating the entire ammonoid dataset is shown in black. (B) Contours for the drag coefficient measured by Chamberlain [36], red lines denote lower drag or better hydrodynamics. (C) Contours for the growth function defined in the main text, red lines denote quicker growth. (D) The contours of the three tasks give rise to a suite of variation denoted by blue points.

Mentions: The maximum of internal volume relative to shell thickness occurs at (D1, W1) = (0.67, 1). This point is close to archetype one The calculated contours of internal volume relative to shell thickness-namely the performance contours of the task of economy- have a curving ridge that points towards the third archetype (Figure 4A). Performance drops sharply on either side of this ridge.Figure 5


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

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

The performance contours of the three putative tasks for ammonoid shells. (A) Contours for shell economy, defined as the ratio of internal volume to shell volume, with red denoting high values, and blue low values. For gyroconic shells (non-overlapping whorls), this performance function becomes constant, and equal to the lowest contour shown (deep blue). The triangle encapsulating the entire ammonoid dataset is shown in black. (B) Contours for the drag coefficient measured by Chamberlain [36], red lines denote lower drag or better hydrodynamics. (C) Contours for the growth function defined in the main text, red lines denote quicker growth. (D) The contours of the three tasks give rise to a suite of variation denoted by blue points.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4404009&req=5

Fig4: The performance contours of the three putative tasks for ammonoid shells. (A) Contours for shell economy, defined as the ratio of internal volume to shell volume, with red denoting high values, and blue low values. For gyroconic shells (non-overlapping whorls), this performance function becomes constant, and equal to the lowest contour shown (deep blue). The triangle encapsulating the entire ammonoid dataset is shown in black. (B) Contours for the drag coefficient measured by Chamberlain [36], red lines denote lower drag or better hydrodynamics. (C) Contours for the growth function defined in the main text, red lines denote quicker growth. (D) The contours of the three tasks give rise to a suite of variation denoted by blue points.
Mentions: The maximum of internal volume relative to shell thickness occurs at (D1, W1) = (0.67, 1). This point is close to archetype one The calculated contours of internal volume relative to shell thickness-namely the performance contours of the task of economy- have a curving ridge that points towards the third archetype (Figure 4A). Performance drops sharply on either side of this ridge.Figure 5

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