Ontogenetic changes in jaw-muscle architecture facilitate durophagy in the turtle<i>Sternotherus minor</i>

Pfaller, Joseph B.; Gignac, Paul M.; Erickson, Gregory M.

doi:10.1242/jeb.048090

Cited by 43 publications

(27 citation statements)

References 44 publications

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“…Therefore, it is not surprising that a central focus of functional morphology studies is to understand how the scaling of the musculoskeletal system influences the scaling of functional traits across ontogeny. Previous studies have argued that ontogenetic shifts in ecology often drive adaptive changes in the scaling of musculoskeletal systems, resulting in differential performance (McMahon, 1984;Richard and Wainwright, 1995;Deban and O'Reilly, 2005;Herrel and Gibb, 2006;Pfaller et al, 2011). These studies, in turn, support the idea that allometric changes in morphology often co-occur with changes in feeding strategies, locomotor behavior or habitat use.…”

Section: Introductionmentioning

confidence: 75%

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Scaling patterns inform ontogenetic transitions away from cleaning in Thalassoma wrasses

Baliga

Mehta

2014

Journal of Experimental Biology

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In fishes, cleaning is a mutualistic behavior wherein a species will remove and consume ectoparasites from other organisms. More than two-thirds of cleaner fishes display this behavior predominately as juveniles and discontinue cleaning as adults; such species are here referred to as 'facultative cleaners'. Whether allometric changes in morphological traits coincide with ontogenetic shifts away from cleaning is unknown. We tested the hypothesis that transitions away from cleaning are associated with scaling patterns in the feeding apparatus of facultative cleaners, and then compared such patterns with those exhibited by non-cleaner congeners. We measured functional traits related to feeding, such as vertical gape distance, premaxillary protrusion distance and maxillary kinematic transmission coefficient (KT) in each ontogenetic series of 11 Thalassoma wrasses (Labridae). As these fishes predominately capture prey via biting, we modeled bite force using MandibLever (v3.3) to create an ontogenetic trajectory of bite force for each species. Our results indicate that cleaner fishes in Thalassoma, as juveniles, possess jaws with low mobility that exhibit weaker bite forces. Additionally, there was remarkable consistency in the range of body lengths over which we observed significant differences between facultative cleaners and non-cleaners in bite force, vertical gape distance and premaxillary protrusion distance. Through ontogeny, facultative cleaner fishes exhibit positive allometry for a number of functionally important feeding traits, which possibly obviates the need to continue cleaning.

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Section: Introductionmentioning

confidence: 75%

“…geometry (Hill, 1950;Schmidt-Nielson, 1984;Emerson and Bramble, 1993;Pfaller et al, 2011). We considered deviations from isometry to be significant if the predicted slopes fell outside the 95% confidence intervals of the slopes we observed.…”

Section: Allometry Of Traitsmentioning

confidence: 99%

Scaling patterns inform ontogenetic transitions away from cleaning in Thalassoma wrasses

Baliga

Mehta

2014

Journal of Experimental Biology

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“…There is little ambiguity in deciding whether a prey item has been crushed, so there is a clear relationship between morphology and performance. The main determinant of predator success is the ability to exert high loads (Pfaller et al, 2011). For this reason it is possible to explore the implications of different predator and prey morphologies and to determine their interactions (Bertness and Cunningham, 1981;Whitenack and Herbert, 2015).…”

Section: Introductionmentioning

confidence: 99%

Morphology does not predict performance: jaw curvature and prey crushing in durophagous stingrays

Kolmann

Crofts

Dean

et al. 2015

Journal of Experimental Biology

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All stingrays in the family Myliobatidae are durophagous, consuming bivalves and gastropods, as well as decapod crustaceans. Durophagous rays have rigid jaws, flat teeth that interlock to form pavement-like tooth plates, and large muscles that generate bite forces capable of fracturing stiff biological composites (e.g. mollusk shell). The relative proportion of different prey types in the diet of durophagous rays varies between genera, with some stingray species specializing on particular mollusk taxa, while others are generalists. The tooth plate module provides a curved occlusal surface on which prey is crushed, and this curvature differs significantly among myliobatids. We measured the effect of jaw curvature on prey-crushing success in durophagous stingrays. We milled aluminum replica jaws rendered from computed tomography scans, and crushed live mollusks, three-dimensionally printed gastropod shells, and ceramic tubes with these fabricated jaws. Our analysis of prey items indicate that gastropods were consistently more difficult to crush than bivalves (i.e. were stiffer), but that mussels require the greatest work-to-fracture. We found that replica shells can provide an important proxy for investigations of failure mechanics. We also found little difference in crushing performance between jaw shapes, suggesting that disparate jaws are equally suited for processing different types of shelled prey. Thus, durophagous stingrays exhibit a many-to-one mapping of jaw morphology to mollusk crushing performance.

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“…These authors were able to identify a high correlation with the increasing of muscle mass and shift in feeding features (Dalrymple, 1977; Pfaller et al, 2010; Pfaller, Gignac & Erickson, 2011). Moreover, there are changes in skull shape associated to the aquatic environment and foraging strategies, as suggested for emydid and testudinoid turtles by Claude et al (2004).…”

Section: Discussionmentioning

confidence: 97%

“…The variation in this area of the skull in turtles was a matter of some studies (e.g., Dalrymple, 1977; Claude et al, 2004; Pfaller, Gignac & Erickson, 2011), which indicated allometric ontogenetic growth patterns of the bones in these regions. These authors were able to identify a high correlation with the increasing of muscle mass and shift in feeding features (Dalrymple, 1977; Pfaller et al, 2010; Pfaller, Gignac & Erickson, 2011).…”

Section: Discussionmentioning

confidence: 97%

Intra-specific variation and allometry of the skull of Late Cretaceous side-necked turtleBauruemys elegans(Pleurodira, Podocnemididae) and how to deal with morphometric data in fossil vertebrates

Mariani

Romano

2017

PeerJ

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BackgroundPrevious quantitative studies on Bauruemys elegans (Suárez, 1969) shell variation, as well as the taphonomic interpretation of its type locality, have suggested that all specimens collected in this locality may have belonged to the same population. We rely on this hypothesis in a morphometric study of the skull. Also, we tentatively assessed the eating preference habits differentiation that might be explained as due to ontogenetic changes.MethodsWe carried out an ANOVA testing 29 linear measurements from 21 skulls of B. elegans taken by using a caliper and through images, using the ImageJ software. First, a Principal Components Analysis (PCA) was performed with 27 measurements (excluding total length and width characters; =raw data) in order to visualize the scatter plots based on the form variance only. Then, a second PCA was carried out using ratios of length and width of each original measurement to assess shape variation among individuals. Finally, original measurements were log-transformed to describe allometries over ontogeny.ResultsNo statistical differences were found between caliper and ImageJ measurements. The first three PCs of the PCA with raw data comprised 70.2% of the variance. PC1 was related to size variation and all others related to shape variation. Two specimens plotted outside the 95% ellipse in PC1∼PC2 axes. The first three PCs of the PCA with ratios comprised 64% of the variance. When considering PC1∼PC2, all specimens plotted inside the 95% ellipse. In allometric analysis, five measurements were positively allometric, 19 were negatively allometric and three represented enantiometric allometry. Many bones of the posterior and the lateral emarginations lengthen due to increasing size, while jugal and the quadratojugal decrease in width.DiscussionImageJ is useful in replacing caliper since there was no statistical differences. Yet iterative imputation is more appropriate to deal with missing data in PCA. Some specimens show small differences in form and shape. Form differences were interpreted as occuring due to ontogeny, whereas shape differences are related to feeding changes during growth. Moreover, all outlier specimens are crushed and/or distorted, thus the form/shape differences may be partially due to taphonomy. The allometric lengthening of the parietal, quadrate, squamosal, maxilla, associated with the narrowing of jugal and quadratojugal may be related to changes in feeding habit between different stages of development. This change in shape might represent a progressive skull stretching and enlargement of posterior and lateral emargination during ontogeny, and consequently, the increment of the feeding-apparatus musculature. Smaller individuals may have fed on softer diet, whereas larger ones probably have had a harder diet, as seen in some living species of Podocnemis. We conclude that the skull variation might be related to differences in feeding habits over ontogeny in B. elegans.

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Ontogenetic changes in jaw-muscle architecture facilitate durophagy in the turtleSternotherus minor

Abstract: There was an error published in the original online version of J. Exp. Biol. 214, 1655-1667. This error occurred in both the PDF and fulltext versions of the online article. The print version is correct.

Cited by 43 publications

References 44 publications

Scaling patterns inform ontogenetic transitions away from cleaning in Thalassoma wrasses

Scaling patterns inform ontogenetic transitions away from cleaning in Thalassoma wrasses

Morphology does not predict performance: jaw curvature and prey crushing in durophagous stingrays

Intra-specific variation and allometry of the skull of Late Cretaceous side-necked turtleBauruemys elegans(Pleurodira, Podocnemididae) and how to deal with morphometric data in fossil vertebrates

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