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

Abstract

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.

Responses to artificial selection for locomotor activity: A focus on death feigning in red flour beetle

“…Previous studies have suggested that differences in sprint speed and locomotor endurance are important (e.g. Druelle et al, 2019;Tan et al, 2020), even for the same locomotor activity, but our results suggest that there is no difference in terms of the effects of death-feigning syndrome between the two traits in T. castaneum.…”

“…In many animals, sprint speed and locomotor endurance are different motor traits, and there are large differences in the effects of each trait on metabolism and external morphology (e.g. Druelle et al, 2019;Tan et al, 2020). Thus, the traits are genetically correlated, and the strength of those relationships, may differ between sprint speed and locomotor endurance.…”

Thermal biology and locomotor performance of the Andean lizardLiolaemus fitzgeraldi(Liolaemidae) in Argentina

“…Though both negative and positive correlations have been reported between sprint speed and endurance for lacertids, agamids and phrynsomatids lizards (de Albuquerque et al, 2015;Tan et al, 2020;Vanhooydonck et al, 2001), for liolaemids lizards no significant associations have been reported (Gómez Alés et al, 2018). Singleton and Garland Jr (2018) found that for Dipsosaurus dorsalis endurance positively correlated to home range size.…”