The relationship between cranial morphology, bite performance, diet and habitat in a radiation of dwarf chameleon (<i>Bradypodion</i>)

Silva, Jessica M. da; Carne, Liza; Measey, John; Herrel, Anthony; Tolley, Krystal A.

doi:10.1111/bij.12819

Cited by 12 publications

(18 citation statements)

References 62 publications

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“…We found evidence for signi cant correlation with a longer closing in-lever and a higher relative importance of Hymenoptera and Diplopoda (Fig. 1), both of which are considered to be rather hard prey (see [17]). The fact that head length, width, and height did not show strong covariation with our diet proxies disagrees with observations for other lizards [5,6,8,34].…”

Section: Discussionmentioning

confidence: 77%

“…We hypothesised ground-dwelling species to have taller heads and thus higher bite forces [13,14]. Finally, we predict species with larger heads and higher bite forces to include larger and harder prey into their diet [7,17]. To test these hypotheses, we compared our ndings with published data on stomach contents from four of the six examined agama species [24].…”

Section: Introductionmentioning

confidence: 98%

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The Relationship Between Bite Force, Morphology, and Diet in Southern African Agamids.

Tan

Measey

Vanhooydonck

et al. 2021

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Background: Many animals display morphological and behavioural adaptations to the habitats in which they live and the resources they exploit. Bite force is an important whole-organism performance trait that allows an increase in dietary breadth, the inclusion of novel prey in the diet, territory and predatory defence, and is important during mating in many lizards. Methods: Here, we study six species of southern African agamid lizards from three habitat types (ground-dwelling, rock-dwelling, and arboreal) to investigate whether habitat use constrains head morphology and bite performance. We further tested whether bite force and head morphology evolve as adaptations to diet by analysing a subset of these species for which diet data were available. Results: Overall, both jaw length and its out-lever are excellent predictors of bite performance across all six species. Rock-dwelling species have a flatter head relative to their size than other species, possibly as an adaptation for crevice use. However, even when correcting for jaw length and jaw out-lever length, rock-dwelling species bite harder than ground-dwelling species. Diet analyses demonstrate that body and head size are not directly related to diet, although greater in-levers for jaw closing (positively related to bite force) are associated to an increase of hard prey in the diet. Ground-dwelling species consume more ants than other species. Conclusions: Our results illustrate the role of head morphology in driving bite force and demonstrate how habitat use impacts head morphology but not bite force in these agamids. Although diet is associated with variation in head morphology it is only partially responsible for the observed differences in morphology and performance.

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Section: Discussionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 98%

The Relationship Between Bite Force, Morphology, and Diet in Southern African Agamids.

Tan

Measey

Vanhooydonck

et al. 2021

Preprint

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“…Animals were brought back to the laboratory measured, tested for bite force and stomach flushed, and then released at the exact site of capture (da Silva et al . ). All experiments (performance measurements, measurements of snout‐vent length and stomach flushing) were conducted within 24 h of capture.…”

Section: Methodsmentioning

confidence: 97%

“…; Wittorski, Losos & Herrel ; da Silva et al . ) or allow a more vertical insertion of these muscles (Herrel, Aerts & De Vree ), resulting in an increased bite force. Although these relationships may seem intuitive at first sight, diet is not the only selective pressure acting on cranial shape and selection for other traits that may trade off with bite force generating capacity may exist.…”

Section: Introductionmentioning

confidence: 99%

Does diet drive the evolution of head shape and bite force in chameleons of the genus Bradypodion?

et al. 2016

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Summary The head is a complex integrated system that is implicated in many vital functions. As such, its morphology is impacted by different and sometimes conflicting demands. Consequently, head shape varies greatly depending on the environment and dietary ecology of an organism. Moreover, given its role in territory defence and mating in lizards, it is also subjected to strong sexual selection in these animals. We investigated the relationships between head shape, bite performance and diet in 14 of the 17 extant Bradypodion species to determine whether variation in diet can explain the observed diversity in bite force and head shape in this genus. We also evaluate differences between sexes in terms of the relationships between head shape, bite force and diet and predict tighter relationships in females given that the head in this sex is principally under natural selection. Our results show that there is indeed a correlation between head shape, diet and bite force, but the direction and magnitude are sex‐dependent. Whereas we observed a correlation between absolute bite force and head shape in both sexes, size‐corrected bite force was correlated with mandible and quadrate shape in females only. Despite strong correlations between bite force and prey hardness, and between prey hardness and head shape, we did not find any relationship between head shape and prey evasiveness. These data suggest that the cranial system in chameleons of the genus Bradypodion evolves under natural selection for the ability to eat large or hard prey. Moreover, significant differences in the ecomorphological relationships between the two sexes suggest that sexual selection plays a role in driving the evolution of bite force and head shape. These data suggest that ecomorphological relationships may be sex‐dependent.

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“…Bite forces have also been linked with intrasexual competition in lizards (e.g. Herrel, De Grauw & Lemos-Espinal, 2001a;Measey et al, 2011;da Silva et al, 2016). If bite force is reduced, due to selective pressures in particular environments causing a change in head morphology, then this may impact diet and sexual competition.…”

Section: Introductionmentioning

confidence: 99%

Diving in head first: trade-offs between phenotypic traits and sand-diving predator escape strategy inMerolesdesert lizards

Edwards

Herrel

Vanhooydonck

et al. 2016

Biol. J. Linn. Soc.

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Survival, in part, depends on an individual's ability to evade predators. In desert regions some lizard species have evolved head‐first sand‐diving strategies to escape predators. To facilitate this behaviour, a distinctive head morphology that facilitates sand‐diving has evolved. This specialised head morphology may, however, come at a cost to other ecologically relevant functions, particularly bite force. Here, we investigated the relationship between morphology and function in a southern African lacertid lizard genus, Meroles, which consists of eight species that utilise different escape strategies, including sand‐diving and running for cover. It was hypothesized that the specialised head morphology of diving species would negatively affect bite force capacity. We found that species from each escape strategy category differed significantly in head shape, but not bite force performance. A phylogenetic tree of the genus was constructed using two mitochondrial and two nuclear genes, and we conducted phylogenetic comparative analyses. One aspect of the head shape differed between the escape strategies once phylogeny was taken into account. We found that bite force may have co‐evolved with head morphology, but that there was no trade‐off between biting capacity and escape strategy in Meroles.

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The relationship between cranial morphology, bite performance, diet and habitat in a radiation of dwarf chameleon (Bradypodion)

Cited by 12 publications

References 62 publications

The Relationship Between Bite Force, Morphology, and Diet in Southern African Agamids.

The Relationship Between Bite Force, Morphology, and Diet in Southern African Agamids.

Does diet drive the evolution of head shape and bite force in chameleons of the genus Bradypodion?

Diving in head first: trade-offs between phenotypic traits and sand-diving predator escape strategy inMerolesdesert lizards

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