Mechanical Design in Organisms

Wainwright, Susan

doi:10.1515/9780691218090

Cited by 309 publications

(154 citation statements)

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“…However, we present it very tentatively. In this study, we have not considered variation in mechanical and physical properties of the various tissues that compose stems (Wainwright et al, 1976;Kull et al, 1992;Speck, 1992;Niklas, 1993), or in other stem traits such as stem length, internodal distance, or presence of septa at intervals in hollow stems (Spatz et al, 1990). Such details are crucial for understanding biomechanical properties of stems.…”

Section: Discussionmentioning

confidence: 99%

Leaf‐stem allometry, hollow stems, and the evolution of caulinary domatia in myrmecophytes

Brouat

McKey

2001

New Phytologist

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Summary• Leaf-stem size relationships over ontogeny were studied here in three different lineages of hollow-stemmed myrmecophytes in order to understand how a new stem function affects morphology.• In each of six taxa, the primary cross-sectional area of a terminal internode and the area of the leaf borne by it were measured on plants representing all stages of ontogeny. Cross-sectional areas of both the cavity and the ring of wood were determined.• The leaf-stem relationship over ontogeny was allometric, in contrast to the isometry previously found in solid-stemmed relatives. Stem cross-sectional area was initially larger relative to leaf area than for solid-stemmed species, increasing less than proportionally with increasing leaf size.• Because mechanical stability requires a minimum ratio of t (thickness of the solid ring) to R (external radius of the cylinder), cross-sectional area of the ring of wood must vary with that of the cavity; both contributed to leaf-stem allometry. Relative to leaves, both are initially large and increase more slowly over ontogeny, suggesting that domatia are particularly costly for plants early in development.

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Section: Discussionmentioning

confidence: 99%

Leaf‐stem allometry, hollow stems, and the evolution of caulinary domatia in myrmecophytes

Brouat

McKey

2001

New Phytologist

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“…Apart form the basic assumptions inherently involved in the bending theory of composites (cf. Wainwright et al 1976;Speck et al 1990;Niklas 1992;Vincent 1992) two main additional assumptions were necessary for the model of Tetraxylopteris. These concerned: (i) the mechanical properties in bending of the outer bark-like tissue of the periderm (figure 8e, f ) which is not readily comparable with biomechanically tested modern barks; and (ii) the mechanical contribution of the two lateral branch traces (figure 8e, f ) which are not longitudinally continuous along the stem but depart at relatively wide angles at the nodes.…”

Section: Assumptionsmentioning

confidence: 99%

Modelling primary and secondary growth processes in plants: a summary of the methodology and new data from an early lignophyte

Speck

Rowe

2003

Phil. Trans. R. Soc. Lond. B

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A mathematical method, based on polar coordinates that allow modelling of primary and secondary growth processes in stems of extant and fossil plants, is summarized and its potential is discussed in comparison with numerical methods using digitizing tablets or electronic image analysing systems. As an example, the modelling of tissue distribution in the internode of an extant sphenopsid (Equisetum hyemale) is presented. In the second half of the paper we present new data of a functional analysis of stem structure and biomechanics of the early lignophyte Tetraxylopteris schmidtii (Middle Devonian) using the polar coordinate method for modelling the tissue distribution in stems of different ontogenetic age. Calculations of the mechanical properties of the stems, based on the modelling of the tissue arrangement, indicate that there is no increase in structural bending modulus throughout the entire development of the plant. The oldest ontogenetic stage has a significantly smaller bending elastic modulus than the intermediate ontogenetic stage, a 'mechanical signal', which is not consistent with a self-supporting growth form. These results, and the ontogenetic variations of the contributions of different stem tissues to the flexural stiffness of the entire stem, are discussed in the evolutionary context of cambial secondary growth.

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“…Therefore, common-sense suggests that of the four factors numbered above, one would expect size (1) and crunch force (4) to be the primary determinants of a predatory mesostigmatid's feeding habit, i.e., the capability of the system. Insect cuticle (and probably other arthropod cuticle) is an excellent material for resisting bending (Wainwright et al 1976), so a substantial force applied is to be expected. Of course for those soil predatory mesostigmatids observed to attack a large worm prey simultaneously in numbers (see Walter and Proctor 2013), size (1) may be less important relative to crunch force (4).…”

Section: The Physics To Explain the Biology Involvedmentioning

confidence: 99%

Feeding design in free-living mesostigmatid chelicerae (Acari: Anactinotrichida)

Bowman

2021

Exp Appl Acarol

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A model based upon mechanics is used in a re-analysis of historical acarine morphological work augmented by an extra seven zoophagous mesostigmatid species. This review shows that predatory mesostigmatids do have cheliceral designs with clear rational purposes. Almost invariably within an overall body size class, the switch in predatory style from a worm-like prey feeding (‘crushing/mashing’ kill) functional group to a micro-arthropod feeding (‘active prey cutting/slicing/slashing' kill) functional group is matched by: an increased cheliceral reach, a bigger chelal gape, a larger morphologically estimated chelal crunch force, and a drop in the adductive lever arm velocity ratio of the chela. Small size matters. Several uropodines (Eviphis ostrinus, the omnivore Trachytes aegrota, Urodiaspis tecta and, Uropoda orbicularis) have more elongate chelicerae (greater reach) than their chelal gape would suggest, even allowing for allometry across mesostigmatids. They may be: plesiosaur-like high-speed strikers of prey, scavenging carrion feeders (like long-necked vultures), probing/burrowing crevice feeders of cryptic nematodes, or small morsel/fragmentary food feeders. Some uropodoids have chelicerae and chelae which probably work like a construction-site mechanical excavator-digger with its small bucket. Possible hoeing/bulldozing, spore-cracking and tiny sabre-tooth cat-like striking actions are discussed for others. Subtle changes lead small mesostigmatids to be predator–scavengers (mesocarnivores) or to be predator–fungivores (hypocarnivores). Some uropodines (e.g., the worm-like prey feeder Alliphis siculus and, Uropoda orbicularis) show chelae similar in design to astigmatids and cryptostigmatids indicating possible facultative saprophagy. Scale matters—obligate predatory designs (hypercarnivory) start for mesostigmatids with chelal gape > 150 μm and cheliceral reach > 350 μm (i.e., about 500–650 μm in body size). Commonality of trophic design in these larger species with solifugids is indicated. Veigaia species with low chelal velocity ratio and other morphological strengthening specialisms, appear specially adapted in a concerted way for predating active soft and fast moving springtails (Collembola). Veigaia cerva shows a markedly bigger chelal gape than its cheliceral reach would proportionately infer suggesting it is a crocodile-like sit-and-wait or ambush predator par excellence. A small chelal gape, low cheliceral reach, moderate velocity ratio variant of the worm-like feeding habit design is supported for phytoseiid pollenophagy. Evidence for a resource partitioning model in the evolution of gnathosomal development is found. A comparison to crustacean claws and vertebrate mandibles is made. Alliphis siculus and Rhodacarus strenzkei are surprisingly powerful mega-cephalics for their small size. Parasitids show a canid-like trophic design. The chelicera of the nematophagous Alliphis halleri shows felid-like features. Glyphtholaspis confusa has hyaena-like cheliceral dentition. The latter species has a markedly smaller chelal gape than its cheliceral reach would suggest proportionately, which together with a high chelal velocity ratio and a high estimated chelal crunch force matches a power specialism of feeding on immobile tough fly eggs/pupae by crushing (durophagy). A consideration of gnathosomal orientation is made. Predatory specialisms appear to often match genera especially in larger mesostigmatids, which may scale quite differently. Comparison to holothyrids and opilioacarids indicates that the cheliceral chelae of the former are cutting-style and those of the latter are crushing-style. A simple validated easy-to-use ‘2:1 on’ predictive algorithm of feeding habit type is included based on a strength-speed tradeoff in chelal velocity ratio for ecologists to test in the field.

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Mechanical Design in Organisms

Cited by 309 publications

References 0 publications

Leaf‐stem allometry, hollow stems, and the evolution of caulinary domatia in myrmecophytes

Leaf‐stem allometry, hollow stems, and the evolution of caulinary domatia in myrmecophytes

Modelling primary and secondary growth processes in plants: a summary of the methodology and new data from an early lignophyte

Feeding design in free-living mesostigmatid chelicerae (Acari: Anactinotrichida)

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