Tooth wear patterns in black rats (Rattus rattus) of Madagascar differ more in relation to human impact than to differences in natural habitats (original) (raw)
Related papers
Enamel microwear in caviomorph rodents
Journal of Mammalogy, 2008
We developed a new data set of enamel microwear for extant caviomorph rodents (i.e., South American hystricognaths) and inferred the diet of an extinct taxon, Neoreomys australis, from data on microwear. To evaluate frequencies of wear features (pits and scratches) in caviomorphs, we employed low-magnification microwear, which has been used successfully by others to distinguish among the diets of ungulates, primates, and sciurid rodents. We developed 3 broad dietary categories for caviomorphs based on behavioral observations reported in the literature: fruit-leaf, fruit-seed, and grass-leaf. Caviomorphs in general all exhibited wear features indicative of processing hard objects (e.g., seed predation, eating hard fruits, and consuming exogenous grit). Among our grass-leaf group, we identified an exogenous-grit subgroup that included fossorial and dust-bathing taxa. We used a discriminant function analysis of wear features to examine post hoc classification of the caviomorph taxa into the 3 dietary categories. Ours is the 1st study to quantify the distribution of microwear features among modern caviomorph rodents; it has the potential to clarify the diets of modern forms that have little behavioral data as well as to infer the diets of extinct species.
A preliminary analysis of dental microwear as a proxy for diet and habitat in shrews
mammalia, 2000
Dental microwear has been shown to reflect diet in a broad variety of fossil mammals. Recent studies have suggested that differences in microwear texture attributes between samples may also reflect environmental abrasive loads. Here, we examine dental microwear textures on the incisors of shrews, both to evaluate this idea and to expand the extant baseline to include Soricidae. Specimens were chosen to sample a broad range of environments, semi-desert to rainforest. Species examined were all largely insectivorous, but some are reported to supplement their diets with vertebrate tissues and others with plant matter. Results indicate subtle but significant differences between samples grouped by both diet independent of environment and environment independent of diet. Subtle diet differences were more evident in microwear texture variation considered by habitat (i.e., grassland). These results suggest that while environment does not swamp the diet signal in shrew incisor microwear, studies can benefit from control of habitat type.
Integrative zoology, 2016
Dental microwear textures have proven to be a valuable tool for reconstructing the diets of a wide assortment of fossil vertebrates. Nevertheless, some studies have recently questioned the efficacy of this approach, suggesting that aspects of habitat unrelated to food preference, especially environmental grit load, might have a confounding effect on microwear patterning that obscures the diet signal. Here we evaluate this hypothesis by examining microwear textures of three extant sympatric rodent species that vary in diet breadth and are found in a variety of habitat types: Mastomys coucha, Micaelamys namaquensis, and Rhabdomys pumilio. We sample each of these species from three distinct environmental settings in southern Africa that differ in rainfall and vegetative cover: Nama-Karoo shrublands (semi-desert) and Dry Highveld grasslands in the Free State Province of South Africa, and Afromontane (wet) grasslands in the highlands of Lesotho. While differences between habitat types ar...
Resource exploitation and competition for food are important selective pressures in animal evolution. A number of recent investigations have focused on linkages between diversification, trophic morphology and diet in bats, partly because their roosting habits mean that for many bat species diet can be quantified relatively easily through faecal analysis. Dietary analysis in mammals is otherwise invasive, complicated, time consuming and expensive. Here we present evidence from insectivorous bats that analysis of three-dimensional (3-D) textures of tooth microwear using International Organization for Standardization (ISO) roughness parameters derived from sub-micron surface data provides an additional, powerful tool for investigation of trophic resource exploitation in mammals. Our approach, like scale-sensitive fractal analysis, offers considerable advantages over twodimensional (2-D) methods of microwear analysis, including improvements in robustness, repeatability and comparability of studies. Our results constitute the first analysis of microwear textures in carnivorous mammals based on ISO roughness parameters. They demonstrate that the method is capable of dietary discrimination, even between cryptic species with subtly different diets within trophic guilds, and even when sample sizes are small. We find significant differences in microwear textures between insectivore species whose diet contains different proportions of 'hard' prey (such as beetles) and 'soft' prey (such as moths), and multivariate analyses are able to distinguish between species with different diets based solely on their tooth microwear textures. Our results show that, compared with previous 2-D analyses of microwear in bats, ISO roughness parameters provide a much more sophisticated characterization of the nature of microwear surfaces and can yield more robust and subtle dietary discrimination. ISO-based textural analysis of tooth microwear thus has a useful role to play, complementing existing approaches, in trophic analysis of mammals, both extant and extinct.
Journal of Zoology, 2013
Resource exploitation and competition for food are important selective pressures in animal evolution. A number of recent investigations have focused on linkages between diversification, trophic morphology and diet in bats, partly because their roosting habits mean that for many bat species diet can be quantified relatively easily through faecal analysis. Dietary analysis in mammals is otherwise invasive, complicated, time consuming and expensive. Here we present evidence from insectivorous bats that analysis of three-dimensional (3-D) textures of tooth microwear using International Organization for Standardization (ISO) roughness parameters derived from sub-micron surface data provides an additional, powerful tool for investigation of trophic resource exploitation in mammals. Our approach, like scale-sensitive fractal analysis, offers considerable advantages over twodimensional (2-D) methods of microwear analysis, including improvements in robustness, repeatability and comparability of studies. Our results constitute the first analysis of microwear textures in carnivorous mammals based on ISO roughness parameters. They demonstrate that the method is capable of dietary discrimination, even between cryptic species with subtly different diets within trophic guilds, and even when sample sizes are small. We find significant differences in microwear textures between insectivore species whose diet contains different proportions of 'hard' prey (such as beetles) and 'soft' prey (such as moths), and multivariate analyses are able to distinguish between species with different diets based solely on their tooth microwear textures. Our results show that, compared with previous 2-D analyses of microwear in bats, ISO roughness parameters provide a much more sophisticated characterization of the nature of microwear surfaces and can yield more robust and subtle dietary discrimination. ISO-based textural analysis of tooth microwear thus has a useful role to play, complementing existing approaches, in trophic analysis of mammals, both extant and extinct.
Tooth wear as a means to quantify intra-specific variations in diet and chewing movements
In mammals, tooth function, and its efficiency, depends both on the mechanical properties of the food and on chewing dynamics. These aspects have rarely been studied in combination and/or at the intra-specific level. Here we applied 3D dental surface texture analysis to a sample of field voles (Microtus agrestis) trapped from Finnish Lapland at different seasons and localities to test for inter-population variations. We also explored intra-individual variation in chewing dynamics by analysing two facets on the second upper molars. Our results confirm that the two localities have similar environments and that the voles feed on the same items there. On the other hand, the texture data suggest that diets are seasonally variable, probably due to varying concentrations of abrasives. Lastly, the textures on the buccal facets are more isotropic and their direction deviates more from the mesial chewing direction than the lingual facets. We interpret these results as reflecting food, rather than chewing, movements, where food particles are more guided on the lingual side of the molars. This has implications for the application of dental microwear analysis to fossils: only homologous facets can be compared, even when the molar row seems to constitute a functional unit. In mammals, teeth are essential to fracture food particles so that enzymes in the digestive track can efficiently extract nutrients. Tooth functionality, therefore, depends on (1) the biomechanical properties of ingesta and (2) the chewing dynamics, related to chewing movements and forces. Tooth function has been approached from three complementary lines of evidence: functional morphology 1,2 , dietary reconstructions 3,4 and reconstructions of chewing mechanics 5,6. It has been shown repeatedly 7 that tooth function cannot be reconstructed solely from the tooth morphology because the form only constraints what an animal can eat and because the actual function (what the animal ate) also depends on other ecological factors like food availability, competition and predation. Therefore, proxies independent of tooth form are required to reconstruct both diet and chewing mechanics. Intra-specific variations in tooth function remain understudied; yet, understanding how and how much tooth function varies intra-specifically, and even intra-individually, is essential to calibrate paleoenvironmental reconstructions based on dietary inferences at the inter-specific level, and to study micro-and macroevolution. Rodents represent an important part of the fossil record due to their abundance, ubiquity and diversity throughout the Cenozoic 8. Additionally, unlike large mammals, rodents are non-migratory and short-lived animals , which make them particularly useful in reconstructions of past climates at local and regional scales. Within rodents, Arvicolinae (voles and lemmings) constitute an excellent mammalian model group for biostratigraphy 9 and terrestrial paleoecological and paleoenvironmental reconstructions 10,11 , as well as for understanding the role of development in the evolution of tooth morphology 12,13. Although it is known from field observations that their diets and habitats are very diverse, arvicolines are usually regarded as grazers in open and cold paleoenviron-ments 14,15. This lack of precision precludes detailed local paleoenvironmental reconstructions. Arvicolines have characteristic prismatic and hypsodont (high crowned) or hypselodont (hypsodont and ever-growing) molars 16. Although the chewing dynamics of arvicolines seems to be quite simple, in which the whole flat molar row shears
Dental microwear texture analysis in mammalian ecology
1. Neoecology and paleoecology both seek to answer the same questions, albeit using different material, at different time scales and with different limitations. Nevertheless, too often, neoecologists neglect paleoecology, and paleoecologists only use neoecology as a baseline for actualism. One reason for this is the lack of tools that can be applied to both fields. 2. This is a review of the contributions to both neoecology and paleoecology of three-dimensional (3D) dental microwear texture analysis (DMTA), a method that can act as a bridge between these fields. 3. DMTA studies can be grouped according to the type of ecological questions researchers seek to answer: specific ecology, intra-specific ecology, niche partitioning and dietary overlap, and ecology over time. The first question has been the main focus of research; the other three were only superficially studied. 4. In this review, selected examples will be presented to demonstrate that DMTA, as one of the few tools that can be applied to both modern and fossil samples, has been used to address key ecological questions in mammalian neoecology and paleoecology. 5. With the wide range of neoecological and paleoecological questions that DMTA can answer, it is clear that this methodology will be used increasingly in the future, possibly in combination with other ecological proxies.
Palaeogeography, Palaeoclimatology, Palaeoecology, 2022
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Dental microwear analysis has proved to be a good indicator of diet and dietary related behaviour in modern humans, fossil hominids and primates. The composition of the diet and the presence of dust and other abrasive particles, are related to microwear rates on the buccal enamel surfaces of molar teeth. Plant food materials such as leaves or stems include phitoliths in larger quantities than fruits or meat. These particles may scratch the enamel surface of teeth during mastication producing a microwear pattern that may be indicative of food choice and food preferences within primate species. In this study we present a dental microwear analysis of extant Cercopithecoidea primates, based on the analysis of more than 200 dental casts obtained from the osteological collection of the National Museum of Kenya (NMK). Specific, sub-specific and also ecological differences are shown to underlie the buccal microwear variability observed within the studied sample. KEYWORDS: Non-occlusal dental microwear – Microstriation – Primates – Cercopithecoidea