scholarly journals Geographic variation in the skull morphology of the lesser grison (Galictis cuja: Carnivora, Mustelidae) from two Brazilian ecoregions

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9388
Author(s):  
Raissa Prior Migliorini ◽  
Rodrigo Fornel ◽  
Carlos Benhur Kasper
Keyword(s):  
Atlantic Forest ◽  
Size Variation ◽  
Neotropical Region ◽  
Shape Variation ◽  
Skull Morphology ◽  
Geometric Morphometric ◽  
Morphological Variations ◽  
Skull Shape ◽  
Temperature And Precipitation ◽  
Forest Region

Background The lesser grison (Galictis cuja) is one of the least known carnivores in the Neotropical region. Its wide geographical occurrence and range of habitats could lead to morphological variations along its distribution. So, this study aimed to investigate the variation in skull shape and size of this species, by testing the existence of ecotypes adapted to their respective environments (Uruguayan savanna and Atlantic Forest), as well as its relationship with selected abiotic variables. Methods The skulls of 52 museum specimens were photographed in the ventral, dorsal, and lateral views, and were analyzed using geometric morphometric techniques. Results We found sexual size dimorphism, with males being larger than females. The shape variation between sexes, as well as between ecoregions, is mostly explained by the effect of allometry. The specimens from Uruguayan savanna are larger than the ones from the Atlantic Forest. Size variation was also significantly correlated to latitude, temperature and precipitation patterns. No correlation between skull shape with geographical distance was detected. Discussion Morphometric measurements and diet data of lesser grison in regions from higher latitudes than our sampling show a tendency to heavier individuals, and the consumption of bigger prey compared to Uruguayan savanna. The results indicated the smaller specimens associated to low variability in annual temperature, congruent to Atlantic Forest region. An explanation for observed variation may be related to the “resource rule” but, due the minimal natural history information regards this species, we can just speculate about this.

scholarly journals Beyond the carapace: skull shape variation and morphological systematics of long-nosed armadillos (genus Dasypus)

2017 ◽  
Author(s):  
Lionel Hautier ◽  
Guillaume Billet ◽  
Benoit De Thoisy ◽  
Frédéric Delsuc
Keyword(s):  
Morphological Variation ◽  
Distinct Species ◽  
Morphological Characters ◽  
Molecular Data ◽  
Guiana Shield ◽  
Shape Variation ◽  
Skull Morphology ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Shape And Size

Background. The systematics of long-nosed armadillos (genus Dasypus) has been mainly based on a handful of external morphological characters and classical measurements. Here, we studied the pattern of morphological variation in the skull of long-nosed armadillos species, with a focus on the systematics of the widely distributed nine-banded armadillo (D. novemcinctus). Methods. We present the first exhaustive 3D comparison of the skull morphology within the genus Dasypus, based on µCT-scans. We used geometric morphometric approaches to explore the patterns of the intra- and interspecific morphological variation of the skull with regard to several factors such as taxonomy, geography, allometry, and sexual dimorphism. Results. We show that the shape and size of the skull vary greatly between Dasypus species, with D. pilosus representing a clear outlier compared to other long-nosed armadillos. The study of the cranial intraspecific variation in D. novemcinctus evidences clear links to the geographic distribution and argue in favour of a revision of past taxonomic delimitations. Our detailed morphometric comparisons detected previously overlooked morphotypes of nine-banded armadillo, especially a very distinctive unit circumscribed to the Guiana Shield. Discussion. As our results are congruent with recent molecular data and analyses of the structure of paranasal sinuses, we propose that D. novemcinctus should be regarded either as a polytypic species (with three to four subspecies) or as a complex of several distinct species.

scholarly journals Beyond the carapace: skull shape variation and morphological systematics of long-nosed armadillos (genus Dasypus)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3650 ◽  
Author(s):  
Lionel Hautier ◽  
Guillaume Billet ◽  
Benoit de Thoisy ◽  
Frédéric Delsuc
Keyword(s):  
Morphological Variation ◽  
Distinct Species ◽  
Morphological Characters ◽  
Molecular Data ◽  
Shape Variation ◽  
Micro Computed Tomography ◽  
Dasypus Novemcinctus ◽  
Skull Morphology ◽  
Geometric Morphometric ◽  
Skull Shape

Background The systematics of long-nosed armadillos (genus Dasypus) has been mainly based on a handful of external morphological characters and classical measurements. Here, we studied the pattern of morphological variation in the skull of long-nosed armadillos species, with a focus on the systematics of the widely distributed nine-banded armadillo (Dasypus novemcinctus). Methods We present the first exhaustive 3D comparison of the skull morphology within the genus Dasypus, based on micro-computed tomography. We used geometric morphometric approaches to explore the patterns of the intra- and interspecific morphological variation of the skull with regard to several factors such as taxonomy, geography, allometry, and sexual dimorphism. Results We show that the shape and size of the skull vary greatly among Dasypus species, with Dasypus pilosus representing a clear outlier compared to other long-nosed armadillos. The study of the cranial intraspecific variation in Dasypus novemcinctus evidences clear links to the geographic distribution and argues in favor of a revision of past taxonomic delimitations. Our detailed morphometric comparisons detected previously overlooked morphotypes of nine-banded armadillos, especially a very distinctive unit restricted to the Guiana Shield. Discussion As our results are congruent with recent molecular data and analyses of the structure of paranasal sinuses, we propose that Dasypus novemcinctus should be regarded either as a polytypic species (with three to four subspecies) or as a complex of several distinct species.

scholarly journals Beyond the carapace: skull shape variation and morphological systematics of long-nosed armadillos (genus Dasypus)

2017 ◽  
Author(s):  
Lionel Hautier ◽  
Guillaume Billet ◽  
Benoit De Thoisy ◽  
Frédéric Delsuc
Keyword(s):  
Morphological Variation ◽  
Distinct Species ◽  
Morphological Characters ◽  
Molecular Data ◽  
Guiana Shield ◽  
Shape Variation ◽  
Skull Morphology ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Shape And Size

Background. The systematics of long-nosed armadillos (genus Dasypus) has been mainly based on a handful of external morphological characters and classical measurements. Here, we studied the pattern of morphological variation in the skull of long-nosed armadillos species, with a focus on the systematics of the widely distributed nine-banded armadillo (D. novemcinctus). Methods. We present the first exhaustive 3D comparison of the skull morphology within the genus Dasypus, based on µCT-scans. We used geometric morphometric approaches to explore the patterns of the intra- and interspecific morphological variation of the skull with regard to several factors such as taxonomy, geography, allometry, and sexual dimorphism. Results. We show that the shape and size of the skull vary greatly between Dasypus species, with D. pilosus representing a clear outlier compared to other long-nosed armadillos. The study of the cranial intraspecific variation in D. novemcinctus evidences clear links to the geographic distribution and argue in favour of a revision of past taxonomic delimitations. Our detailed morphometric comparisons detected previously overlooked morphotypes of nine-banded armadillo, especially a very distinctive unit circumscribed to the Guiana Shield. Discussion. As our results are congruent with recent molecular data and analyses of the structure of paranasal sinuses, we propose that D. novemcinctus should be regarded either as a polytypic species (with three to four subspecies) or as a complex of several distinct species.

scholarly journals Individual variation of the masticatory system dominates 3D skull shape in the herbivory-adapted marsupial wombats

2019 ◽  
Author(s):  
Vera Weisbecker ◽  
Thomas Guillerme ◽  
Cruise Speck ◽  
Emma Sherratt ◽  
Hyab Mehari Abraha ◽  
...  
Keyword(s):  
Individual Variation ◽  
Principal Component ◽  
Individual Variability ◽  
Shape Variation ◽  
Mandibular Ramus ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Marsupial Species ◽  
Masticatory System ◽  
The Individual

AbstractBackgroundWithin-species skull shape variation of marsupial mammals is widely considered low and strongly size-dependent (allometric), possibly due to developmental constraints arising from the altricial birth of marsupials. However, species whose skulls are impacted by strong muscular stresses – particularly those produced through mastication of tough food items – may not display such intrinsic patterns very clearly because of the known plastic response of bone to muscle activity of the individual. In such cases, shape variation should not be dominated by allometry; ordination of shape in a geometric morphometric context through principal component analysis (PCA) should reveal main variation in areas under masticatory stress (incisor region/zygomatic arches/mandibular ramus); but this main variation should emerge from high individual variability and thus have low eigenvalues.ResultsWe assessed the evidence for high individual variation through 3D geometric morphometric shape analysis of crania and mandibles of thre species of grazing-specialized wombats, whose diet of tough grasses puts considerable strain on their masticatory system. As expected, we found little allometry and low Principal Component 1 (PC1) eigenvalues within crania and mandibles of all three species. Also as expected, the main variation was in the muzzle, zygomatic arches, and masticatory muscle attachments of the mandibular ramus. We then implemented a new test to ask if the landmark variation reflected on PC1 was reflected in individuals with opposite PC1 scores and with opposite shapes in Procrustes space. This showed that correspondence between individual and ordinated shape variation was limited, indicating high levels of individual variability in the masticatory apparatus.DiscussionOur results are inconsistent with hypotheses that skull shape variation within marsupial species reflects a constraint pattern. Rather, they support suggestions that individual plasticity can be an important determinant of within-species shape variation in marsupials (and possibly other mammals) with high masticatory stresses, making it difficult to understand the degree to which intrinsic constraint act on shape variation at the within-species level. We conclude that studies that link micro- and macroevolutionary patterns of shape variation might benefit from a focus on species with low-impact mastication, such as carnivorous or frugivorous species.

scholarly journals Phylogeny and adaptation shape the teeth of insular mice

2016 ◽  
Vol 283 (1824) ◽  
pp. 20152820 ◽  
Author(s):  
Ronan Ledevin ◽  
Pascale Chevret ◽  
Guila Ganem ◽  
Janice Britton-Davidian ◽  
Emilie A. Hardouin ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Size Variation ◽  
Wood Mouse ◽  
Relative Role ◽  
Resource Exploitation ◽  
Shape Variation ◽  
Geometric Morphometric ◽  
Competition Level ◽  
History Of

By accompanying human travels since prehistorical times, the house mouse dispersed widely throughout the world, and colonized many islands. The origin of the travellers determined the phylogenetic source of the insular mice, which encountered diverse ecological and environmental conditions on the various islands. Insular mice are thus an exceptional model to disentangle the relative role of phylogeny, ecology and climate in evolution. Molar shape is known to vary according to phylogeny and to respond to adaptation. Using for the first time a three-dimensional geometric morphometric approach, compared with a classical two-dimensional quantification, the relative effects of size variation, phylogeny, climate and ecology were investigated on molar shape diversity across a variety of islands. Phylogeny emerged as the factor of prime importance in shaping the molar. Changes in competition level, mostly driven by the presence or absence of the wood mouse on the different islands, appeared as the second most important effect. Climate and size differences accounted for slight shape variation. This evidences a balanced role of random differentiation related to history of colonization, and of adaptation possibly related to resource exploitation.

scholarly journals Individual variation of the masticatory system dominates 3D skull shape in the herbivory-adapted marsupial wombats

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Vera Weisbecker ◽  
Thomas Guillerme ◽  
Cruise Speck ◽  
Emma Sherratt ◽  
Hyab Mehari Abraha ◽  
...  
Keyword(s):  
Individual Variation ◽  
Principal Component ◽  
Individual Variability ◽  
Shape Variation ◽  
Mandibular Ramus ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Marsupial Species ◽  
Masticatory System ◽  
The Individual

Abstract Background Within-species skull shape variation of marsupial mammals is widely considered low and strongly size-dependent (allometric), possibly due to developmental constraints arising from the altricial birth of marsupials. However, species whose skulls are impacted by strong muscular stresses – particularly those produced through mastication of tough food items – may not display such intrinsic patterns very clearly because of the known plastic response of bone to muscle activity of the individual. In such cases, allometry may not dominate within-species shape variation, even if it is a driver of evolutionary shape divergence; ordination of shape in a geometric morphometric context through principal component analysis (PCA) should reveal main variation in areas under masticatory stress (incisor region/zygomatic arches/mandibular ramus); but this main variation should emerge from high individual variability and thus have low eigenvalues. Results We assessed the evidence for high individual variation through 3D geometric morphometric shape analysis of crania and mandibles of three species of grazing-specialized wombats, whose diet of tough grasses puts considerable strain on their masticatory system. As expected, we found little allometry and low Principal Component 1 (PC1) eigenvalues within crania and mandibles of all three species. Also as expected, the main variation was in the muzzle, zygomatic arches, and masticatory muscle attachments of the mandibular ramus. We then implemented a new test to ask if the landmark variation reflected on PC1 was reflected in individuals with opposite PC1 scores and with opposite shapes in Procrustes space. This showed that correspondence between individual and ordinated shape variation was limited, indicating high levels of individual variability in the masticatory apparatus. Discussion Our results are inconsistent with hypotheses that skull shape variation within marsupial species reflects a constraint pattern. Rather, they support suggestions that individual plasticity can be an important determinant of within-species shape variation in marsupials (and possibly other mammals) with high masticatory stresses, making it difficult to understand the degree to which intrinsic constraints act on shape variation at the within-species level. We conclude that studies that link micro- and macroevolutionary patterns of shape variation might benefit from a focus on species with low-impact mastication, such as carnivorous or frugivorous species.

scholarly journals Geometric morphometric analysis of skull morphology reveals loss of phylogenetic signal at the generic level in extant lagomorphs (Mammalia: Lagomorpha)

2015 ◽  
Vol 84 (4) ◽  
pp. 267-284 ◽  
Author(s):  
Deyan Ge ◽  
Lu Yao ◽  
Lin Xia ◽  
Zhaoqun Zhang ◽  
Qisen Yang
Keyword(s):  
Dna Sequences ◽  
Shape Change ◽  
Morphological Evolution ◽  
Phylogenetic Signal ◽  
Lateral View ◽  
Skull Morphology ◽  
Generic Level ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Long Time

The intergeneric phylogeny of Lagomorpha had been controversial for a long time before a robust phylogeny was reconstructed based on seven nuclear and mitochondrial DNA sequences. However, skull morphology of several endemic genera remained poorly understood. The morphology of supraorbital processes in Lagomorpha is normally used as a diagnostic characteristic in taxonomy, but whether shape change of this structure parallels its genetic divergence has not been investigated. In this study, we conducted a comparative analysis of the skull morphology of all 12 extant genera using geometric morphometrics. These results indicated that no significant phylogenetic signal is observed in the shape change of the dorsal and ventral views of the cranium as well as in the lateral view of the mandible. The supraorbital processes also show insignificant phylogenetic signal in shape change. Similarly, mapping the centroid size (averaged by genus) of these datasets onto the phylogeny also showed insignificant phylogenetic signal. Aside from homoplasy caused by convergent evolution of skull shape, the massive extinction of lagomorphs after the late Miocene is proposed as one of the main causes for diluting phylogenetic signals in their morphological evolution. Acknowledging the loss of phylogenetic signals in skull shape and supraorbital processes of extant genera sheds new light on the long-standing difficulties for understanding higher-level systematics in Lagomorpha.

scholarly journals Are subspecies (of Eira barbara) real?

2020 ◽  
Vol 101 (5) ◽  
pp. 1410-1425
Author(s):  
Mauro Ignacio Schiaffini
Keyword(s):  
Conceptual Framework ◽  
Size Variation ◽  
Species Level ◽  
Morphological Data ◽  
Modern Concept ◽  
Climate Data ◽  
Skull Morphology ◽  
Skull Shape ◽  
Components Analysis ◽  
Eira Barbara

Abstract The subspecies concept is one of the most controversial in Linnean taxonomy. In the past, subspecies were described without a clear conceptual framework, triggering confusion and motivating criticism of the very concept of a subspecies. At present, subspecies are conceived as aggregates of populations that are geographically isolated, are composed of interfertile individuals, and are morphologically diagnosable. The tayra, Eira barbara, was described in 1758 and has had a stable taxonomic history at the species level. However, below the species level, 16 subspecies have been named, with from two to seven subspecies recognized as valid by different authors. None of the subspecies were, however, described within a clear conceptual framework. Using the modern concept of a subspecies, I analyzed subspecies of E. barbara recognized by recent authors. I gathered morphometric data from 155 specimens in mammal collections, georeferenced each specimen, and recorded membership to subspecies assigned by different references and by its location. I gathered climate and geographic data for each location. I analyzed data using Principal Components Analysis (PCA) and analysis of variance (ANOVA). Specimens exhibited sexual dimorphism in size but not in skull shape. I used regression analysis to test for associations between skull shape and size and climate data. Geographic analyses documented that subspecies are not allopatric, violating one of the main properties of the subspecies concept. ANOVA showed significant differences in skull morphology between some pairs of recognized subspecies but not others. However, none of the subspecies segregated in the PCA. Thus, the recognized subspecies could not be diagnosed from morphological data, violating another property of the subspecies concept. Size varied greatly between the sexes using different schemes for recognized subspecies. Climate variables explained between 4% and 6% of size variation for males and females. Skull shape proved not to be geographically variable.

scholarly journals Wing Geometry Analysis of Aedes aegypti (Diptera, Culicidae), a Dengue Vi-rus Vector, from Multiple Geographical Locations of Samut Songkhram, Thailand

2019 ◽  
Author(s):  
Tanawat Chaiphongpachara ◽  
Nattapon Juijayen ◽  
Kitthisak Khlaeo Chansukh
Keyword(s):  
Aedes Aegypti ◽  
Size Variation ◽  
Public Health Problem ◽  
Major Public Health Problem ◽  
Mosquito Vector ◽  
Shape Variation ◽  
Residential Areas ◽  
Geometric Morphometric ◽  
Wing Geometry ◽  
Living Organisms

Background: Dengue Haemorrhagic Fever (DHF) is a mosquito-borne disease and remains a major public health problem, especially in tropical and temperate countries. Studying wing morphometric of Aedes aegypti as a mosquito vector of DHF can help to better understand biological process of the mosquito adaptation to the environment. We aimed to study the geometric morphometric of Ae. aegypti from multiple geographical areas. Methods: Samples were collected from Samut Songkhram Province in Thailand, including coastal, residential and cultivated areas, by Ovitrap once per month during Oct to Nov 2016. Results: According to size variation analysis of Ae. aegypti, the female mosquito in a cultivated area was significant­ly different from those in the coastal and residential areas (P< 0.05). Whereas male Ae. aegypti in a cultivated area were significantly different from those in a residential area (P< 0.05). The shape variation of both female and male Ae. aegypti from all areas was statistically different (P< 0.05). Conclusion: Normally, living organisms, including mosquitoes, are adapted to their environment. The studied geo­graphical locations affect Ae. aegypti morphology.

scholarly journals Ontogenetic shift in diet of a large elapid snake is facilitated by allometric change in skull morphology

2021 ◽  
Author(s):  
Matthew Brenton Patterson ◽  
Ashleigh K Wolfe ◽  
Patricia A Fleming ◽  
Philip W Bateman ◽  
Meg Martin ◽  
...  
Keyword(s):  
Body Size ◽  
Morphological Changes ◽  
Full Range ◽  
Stomach Contents ◽  
Prey Type ◽  
Postnatal Ontogeny ◽  
Shape Variation ◽  
Ontogenetic Changes ◽  
Skull Morphology ◽  
Skull Shape

Abstract As snakes are limbless, gape-limited predators, their skull is the main feeding structure involved in prey handling, manipulation and feeding. Ontogenetic changes in prey type and size are likely to be associated with distinct morphological changes in the skull during growth. We investigated ontogenetic variation in diet from stomach contents of n = 161 dugite specimens (Pseudonaja affinis, Elapidae) representing the full range of body size for the species, and skull morphology of 46 specimens (range 0.25–1.64 m snout-vent-length; SVL). We hypothesised that changes in prey type throughout postnatal ontogeny would coincide with distinct changes in skull shape. Dugites demonstrate a distinct size-related shift in diet: the smallest individuals ate autotomised reptile tails, medium-sized individuals predominantly ate small reptiles (as snakes grew larger there was an increased likelihood of feeding on reptiles head-first), and the largest individuals (> 0.8 m SVL) ate mammals and large reptiles. Morphometric analysis revealed that ~ 40% of the variation in skull shape was associated with body size (SVL). Through ontogeny, skulls changed from a smooth, bulbous cranium with relatively small trophic bones (upper and lower jaws and their attachments), to more rugous bones (as an adaption for muscle attachment) and relatively longer trophic bones that would extend gape. Individual shape variation in trophic bone dimensions was greater in larger adults and this likely reflects natural plasticity of individuals feeding on different prey sizes/types. Rather than a distinct morphological shift with diet, the ontogenetic changes were consistent, but positive allometry of individual trophic bones resulted in disproportionate growth of the skull, reflected in increased gape size and mobility of jaw bones in adults to aid the ingestion of larger prey and improve manipulation and processing ability. These results indicate that allometric scaling is an important mechanism by which snakes can change their dietary niche.

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