Life in Burrows Channelled the Morphological Evolution of the Skull in Rodents: the Case of African Mole-Rats (Bathyergidae, Rodentia)

Rodrigues, Helder Gomes; Šumbera, Radim; Hautier, Lionel

doi:10.1007/s10914-015-9305-x

Cited by 51 publications

(59 citation statements)

References 45 publications

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“…chisel-tooth digging in Fukomys and scratch digging in Bathyergus [2]. Previous studies of subterranean rodents have indicated that digging behaviour has a major impact on cranial morphology [15,16] and that chisel-tooth digging species have adaptations for high bite force and wide gape [6,10]. The cranial morphology of the chisel-tooth digger in this analysis is clearly able to function well at wide gapes, and, although absolute bite force cannot be predicted with any degree of confidence by our unvalidated models, increasing the efficiency of the masticatory system would necessarily increase bite force.…”

Section: Resultsmentioning

confidence: 99%

“…This result is as predicted by the third hypothesis and fits with the digging behaviour of these two species. It appears that in Fukomys the morphology of the cranium leads to reduced deformation at the wide gapes necessary for chisel-tooth digging [6,10]. Bathyergus , as a scratch digger [2], does not employ such wide gapes as frequently, and thus its cranial morphology deforms least at narrower gapes.…”

Section: Discussionmentioning

confidence: 99%

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The impact of gape on the performance of the skull in chisel-tooth digging and scratch digging mole-rats (Rodentia: Bathyergidae)

McIntosh

Cox

2016

R. Soc. open sci.

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The African mole-rats (Bathyergidae) are a family of rodents highly adapted for life underground. Previous research has shown that chisel-tooth digging mole-rats (which use their incisors to dig burrows) are clearly distinguishable from scratch diggers (which only use the forelimbs to tunnel) on the basis of morphology of the skull, and that the differences are linked to the production of high bite forces and wide gapes. We hypothesized that the skull of a chisel-tooth digging mole-rat would perform better at wider gapes than that of a scratch digging mole-rat during incisor biting. To test this hypothesis, we created finite-element models of the cranium of the scratch digging Bathyergus suillus and the chisel-tooth digging Fukomys mechowii, and loaded them to simulate incisor bites at different gapes. Muscle loads were scaled such that the ratio of force to surface area was the same in both models. We measured three performance variables: overall stress across the cranium, mechanical efficiency of biting and degree of deformation across the skull. The Fukomys model had a more efficient incisor bite at all gapes, despite having greater average stress across the skull. In addition, the Fukomys model deformed less at wider gapes, whereas the Bathyergus model deformed less at narrower gapes. These properties of the cranial morphology of Fukomys and Bathyergus are congruent with their respective chisel-tooth and scratch digging behaviours and, all other factors being equal, would enable the more efficient production of bite force at wider gapes in Fukomys. However, in vivo measurements of muscle forces and activation patterns are needed to fully understand the complex biomechanics of tooth digging.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The impact of gape on the performance of the skull in chisel-tooth digging and scratch digging mole-rats (Rodentia: Bathyergidae)

McIntosh

Cox

2016

R. Soc. open sci.

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“…The convergence of ecology and morphology is especially well documented for rodents living on different continents (Wood 1947; Samuels and van Valkenburgh ; Rodrigues et al. ). Wood (, p. 250) once observed “‘Parallelism, parallelism, more parallelism and still more parallelism’ is the evolutionary motto of the rodents.”…”

mentioning

confidence: 99%

“…Although most rodents have generalized diets, highly specialized forms, such as strict carnivores, insectivores, and herbivores, can show convergence in morphology (Samuels 2009;Rowe et al 2016). The convergence of ecology and morphology is especially well documented for rodents living on different continents (Wood 1947;Samuels and van Valkenburgh 2008;Rodrigues et al 2015). Wood (1935, p. 250) once observed "'Parallelism, parallelism, more parallelism and still more parallelism' is the evolutionary motto of the rodents.…”

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confidence: 99%

The ecology of a continental evolutionary radiation: Is the radiation of sigmodontine rodents adaptive?

et al. 2017

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Evolutionary radiations on continents are less well-understood and appreciated than those occurring on islands. The extent of ecological influence on species divergence can be evaluated to determine whether a radiation was ultimately the outcome of divergent natural selection or else arose mainly by nonecological divergence. Here, we used phylogenetic comparative methods to test distinct hypotheses corresponding to adaptive and nonadaptive evolutionary scenarios for the morphological evolution of sigmodontine rodents. Results showed that ecological variables (diet and life-mode) explain little of the shape and size variation of sigmodontine skulls and mandibles. A Brownian model with varying rates for insectivory versus all other diets was the most likely evolutionary model. The insectivorous sigmodontines have a faster rate of morphological evolution than mice feeding on other diets, possibly due to stronger selection for features that aid insectivory. We also demonstrate that rapid early-lineage diversification is not accompanied by high morphological divergence among subclades, contrasting with island results. The geographic size of continents permits spatial segregation to a greater extent than on islands, allowing for allopatric distributions and escape from interspecific competition. We suggest that continental radiations of rodents are likely to produce a pattern of high species diversification coupled with a low degree of phenotypic specialization.

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“…To elucidate the functional significance of any morphological variation between red squirrel populations, the mechanical advantage (MA) of three of the major jaw-closing muscles – temporalis, superficial masseter, and deep masseter – was estimated from linear measurements of the jaw (following Casanovas-Vilar and van Dam, 2013; Gomes Rodrigues et al 2016). MA was calculated as the ratio of the muscle in-lever to the biting out-lever.…”

Section: Methodsmentioning

confidence: 99%

Population fragmentation leads to morpho-functional variation in British red squirrels (Sciurus vulgaris)

Cox

Morris

Kitchener

2019

Preprint

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26It is well-known that population fragmentation and isolation can lead to rapid morphological 27 and functional divergence, with the effect being particularly well-documented in rodents. Here, 28 we investigated whether such a phenomenon could be identified in the Eurasian red squirrel 29 (Sciurus vulgaris), which was once widespread across the majority of Great Britain, but 30 suffered a severe population decline across the 20 th century, leaving a highly fragmented 31 distribution. The aim was to test for morphological and biomechanical variation of the 32 mandible between the remaining British red squirrel populations. Linear and geometric 33 morphometric methods were used to analyse shape in a sample of over 250 squirrel mandibles 34 from across the UK and Germany. Canonical variates analysis identified significant shape 35 differences between most British red squirrel populations, but particularly between squirrels 36 from Formby and those from other populations. Linear measurements showed that Formby red 37 squirrels have a significantly lower mechanical advantage of the temporalis muscle, indicating 38 that they are less efficient at gnawing. We suggest that this difference may be related to past 39 supplemental feeding of Formby squirrels with peanuts, which are less mechanically resistant 40 than food items that occur naturally in the diet of British red squirrels. 41 42 43 44 45 46 47 48It is well-established that fragmentation of a population and the resulting isolation of the 52

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Life in Burrows Channelled the Morphological Evolution of the Skull in Rodents: the Case of African Mole-Rats (Bathyergidae, Rodentia)

Cited by 51 publications

References 45 publications

The impact of gape on the performance of the skull in chisel-tooth digging and scratch digging mole-rats (Rodentia: Bathyergidae)

The impact of gape on the performance of the skull in chisel-tooth digging and scratch digging mole-rats (Rodentia: Bathyergidae)

The ecology of a continental evolutionary radiation: Is the radiation of sigmodontine rodents adaptive?

Population fragmentation leads to morpho-functional variation in British red squirrels (Sciurus vulgaris)

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