Skull-shape variation and modularity in two Japanese field mice, Apodemus speciosus and Apodemus argenteus (Rodentia: Muridae)

2020 ◽  
Vol 287 ◽  
pp. 147-159
Author(s):  
Jadab Kumar Biswas ◽  
Masaharu Motokawa
Keyword(s):  
Shape Variation ◽  
Apodemus Speciosus ◽  
Skull Shape ◽  
Apodemus Argenteus ◽  
Field Mice

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 Relative skull size as one of the factors limiting skull shape variation in passerines

2021 ◽  
Author(s):  
Oksana Shatkovska ◽  
Maria Ghazali
Keyword(s):  
Body Mass ◽  
Shape Variation ◽  
Absolute Size ◽  
Terrestrial Locomotion ◽  
Skull Shape ◽  
Skull Size ◽  
Dietary Preferences ◽  
Wide Range ◽  
Body Sizes ◽  
Biomechanical Constraints

Despite a considerable interest of researchers to the issue of variation in skull shapes of birds and factors influencing it, some drivers associated with the design features of an entire bird body, which are important for both successful terrestrial locomotion and flight, are overlooked. One of such factors, in our opinion, is relative skull size (skull length in relation to body mass), which can affect the position of the body's center of gravity. We tested effects of relative skull size, allometry (i.e. absolute skull size), and diet on variation in skull shape. The study was conducted on 50 songbird species with a wide range of body mass (8.3g to 570g) and dietary preferences (granivores, insectivores/granivores, insectivores, omnivores). Skull shape was analyzed using 2D geometric morphometrics. We revealed that similar patterns of skull shape occur among passerines with different body sizes and diets. The relative skull size predicted skull shape to a similar extent and with a similar pattern as the absolute size. In our opinion, the effect of the relative skull size on skull shape variation is likely due to biomechanical constraints related to flight.

Morphological variation of large Japanese field mice, Apodemus speciosus on the Izu and Oki Islands

Mammal Study ◽  
2006 ◽  
Vol 31 (1) ◽  
pp. 29-40 ◽  
Author(s):  
Yasushi Takada ◽  
Eiichi Sakai ◽  
Yasushi Uematsu ◽  
Takashi Tateishi
Keyword(s):  
Morphological Variation ◽  
Apodemus Speciosus ◽  
Field Mice

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 Prevalence and Genetic Diversity of Bartonella Species Isolated from Wild Rodents in Japan

2008 ◽  
Vol 74 (16) ◽  
pp. 5086-5092 ◽  
Author(s):  
Kai Inoue ◽  
Soichi Maruyama ◽  
Hidenori Kabeya ◽  
Naoyuki Yamada ◽  
Norio Ohashi ◽  
...  
Keyword(s):  
Rattus Rattus ◽  
Wild Rodents ◽  
Apodemus Speciosus ◽  
Suburban Areas ◽  
Genetic Groups ◽  
Causative Agents ◽  
Apodemus Argenteus ◽  
Species Groups ◽  
First Time ◽  
Dual Infections

ABSTRACT Here, we describe for the first time the prevalence and genetic properties of Bartonella organisms in wild rodents in Japan. We captured 685 wild rodents throughout Japan (in 12 prefectures) and successfully isolated Bartonella organisms from 176 of the 685 rodents (isolation rate, 25.7%). Those Bartonella isolates were all obtained from the rodents captured in suburban areas (rate, 51.8%), but no organism was isolated from the animals captured in city areas. Sequence analysis of rpoB and gltA revealed that the Bartonella isolates obtained were classified into eight genetic groups, comprising isolates closely related to B. grahamii (A-I group), B. tribocorum and B. elizabethae (B-J group), B. tribocorum and B. rattimassiliensis (C-K group), B. rattimassiliensis (D-L group), B. phoceensis (F-N group), B. taylorii (G-O group), and probably two additional novel Bartonella species groups (E-M and H-P). B. grahamii, which is one of the potential causative agents of human neuroretinitis, was found to be predominant in Japanese rodents. In terms of the relationships between these Bartonella genetic groups and their rodent species, (i) the A-I, E-M, and H-P groups appear to be associated with Apodemus speciosus and Apodemus argenteus; (ii) the C-K, D-L, and F-N groups are likely implicated in Rattus rattus; (iii) the B-J group seems to be involved in Apodemus mice and R. rattus; and (iv) the G-O group is probably associated with A. speciosus and Clethrionomys voles. Furthermore, dual infections with two different genetic groups of bartonellae were found in A. speciosus and R. rattus. These findings suggest that the rodent in Japan might serve as a reservoir of zoonotic Bartonella infection.

The status of the genus Hokkaidocephala Tenora, Gulyaev & Kamiya, 1999 (Cestoda: Anoplocephalidae), parasites of the endemic Japanese field mice (Apodemus spp.)

Zootaxa ◽  
2008 ◽  
Vol 1925 (1) ◽  
pp. 62-68
Author(s):  
VOITTO HAUKISALMI ◽  
MITSUHIKO ASAKAWA ◽  
ANDRÁS GUBÁNYI
Keyword(s):  
Type Species ◽  
Seminal Receptacle ◽  
Maximum Size ◽  
Reproductive Organs ◽  
Seminal Vesicles ◽  
Valid Genus ◽  
The Status ◽  
Apodemus Argenteus ◽  
Field Mice ◽  
Specific Species

The present study reconsiders the status of the genus Hokkaidocephala Tenora, Gulyaev & Kamiya, 1999 by examining available specimens of the type species H. apodemi (Iwaki, Tenora, Abe, Oku & Kamiya, 1994) (syn. Andrya apodemi) and comparing them with related anoplocephaline cestodes. It is shown that Hokkaidocephala apodemi does not differ fundamentally from related genera in the development of the reproductive organs, contrary to the argument of Tenora et al. (1999). In Hokkaidocephala and related genera (Anoplocephaloides Baer, 1923 s. str. and Microcephaloides Haukisalmi, Hardman, Hardman, Rausch & Henttonen, 2008), sperm appears in the seminal receptacle (female organ) simultaneously or slightly earlier than in the seminal vesicles (male organs) and the ovary and vitellarium are absent in postmature proglottides where testes still persist and usually reach their maximum size. However, Hokkaidocephala is considered here a valid genus differentiated from the related genera by its unique uterine structure and development. Presently, Hokkaidocephala includes two host-specific species [H. apodemi and H. baeri (Rausch, 1976) n. comb. (= Anoplocephaloides baeri Rausch, 1976)] parasitizing endemic Japanese field mice (primarily Apodemus argenteus).

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