Research

21 pages, 4540 KiB

Open AccessArticle

A Comparison of Semilandmarking Approaches in the Analysis of Size and Shape

by Wuyang Shui, Antonio Profico and Paul O’Higgins

Animals 2023, 13(7), 1179; https://doi.org/10.3390/ani13071179 - 28 Mar 2023

Cited by 3 | Viewed by 1320

Often, few landmarks can be reliably identified in analyses of form variation and covariation. Thus, ‘semilandmarking’ algorithms have increasingly been applied to surfaces and curves. However, the locations of semilandmarks depend on the investigator’s choice of algorithm and their density. In consequence, to [...] Read more.

Often, few landmarks can be reliably identified in analyses of form variation and covariation. Thus, ‘semilandmarking’ algorithms have increasingly been applied to surfaces and curves. However, the locations of semilandmarks depend on the investigator’s choice of algorithm and their density. In consequence, to the extent that different semilandmarking approaches and densities result in different locations of semilandmarks, they can be expected to yield different results concerning patterns of variation and co-variation. The extent of such differences due to methodology is, as yet, unclear and often ignored. In this study, the performance of three landmark-driven semilandmarking approaches is assessed, using two different surface mesh datasets (ape crania and human heads) with different degrees of variation and complexity, by comparing the results of morphometric analyses. These approaches produce different semilandmark locations, which, in turn, lead to differences in statistical results, although the non-rigid semilandmarking approaches are consistent. Morphometric analyses using semilandmarks must be interpreted with due caution, recognising that error is inevitable and that results are approximations. Further work is needed to investigate the effects of using different landmark and semilandmark templates and to understand the limitations and advantages of different semilandmarking approaches. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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11 pages, 2659 KiB

Open AccessArticle

Examination of Shape Variation of the Skull in British Shorthair, Scottish Fold, and Van Cats

by Ozan Gündemir, Tomasz Szara, Ebru Eravci Yalin, Murat Karabagli, Zihni Mutlu, Osman Yilmaz, Serkan Kemal Büyükünal, Milos Blagojevic and Pere M. Parés-Casanova

Animals 2023, 13(4), 614; https://doi.org/10.3390/ani13040614 - 09 Feb 2023

Cited by 5 | Viewed by 2301

Abstract

A variety of skull shapes are frequently used for discrimination between animal species, breeds, and sexes. In this study, skulls of three different breeds of cats were examined by the geometric morphometric method, with the aim of revealing skull shape differences. For this [...] Read more.

A variety of skull shapes are frequently used for discrimination between animal species, breeds, and sexes. In this study, skulls of three different breeds of cats were examined by the geometric morphometric method, with the aim of revealing skull shape differences. For this purpose, 27 cats (6 British Shorthair, 7 Scottish Fold, and 14 Van cats) were used. The skulls of cats were modeled by computed tomography. Geometric morphometrics was applied using dorsal (8 landmarks, 63 semilandmarks) and lateral (8 landmarks, 63 semilandmarks) skull projections on these models. Centroid size differences between the breeds were statistically insignificant. However, the differences in shape were statistically significant for both the dorsal view and lateral view. Shape variation was less in the British Shorthair than in other breeds. Shape differences generally occurred around the orbit. In the skull of Scottish Folds, the orbit was situated more caudally than in other breeds. The British Shorthair had the largest orbital ring. In dorsal view, the Scottish Fold had the largest orbital diameter. The orbital ring of Van cats was smallest in both dorsal and lateral views. In the canonical variate analysis, it was seen that the breeds were separated from each other. The shape difference in the skull between different cat breeds could be revealed by geometric morphometrics. The results of this study provide useful information for taxonomy. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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36 pages, 11071 KiB

Open AccessArticle

A Comparison of Semilandmarking Approaches in the Visualisation of Shape Differences

by Wuyang Shui, Antonio Profico and Paul O’Higgins

Animals 2023, 13(3), 385; https://doi.org/10.3390/ani13030385 - 23 Jan 2023

Cited by 3 | Viewed by 1443

Abstract

In landmark-based analyses of size and shape variation and covariation among biological structures, regions lacking clearly identifiable homologous landmarks are commonly described by semilandmarks. Different algorithms may be used to apply semilandmarks, but little is known about the consequences of analytical results. Here, [...] Read more.

In landmark-based analyses of size and shape variation and covariation among biological structures, regions lacking clearly identifiable homologous landmarks are commonly described by semilandmarks. Different algorithms may be used to apply semilandmarks, but little is known about the consequences of analytical results. Here, we assess how different approaches and semilandmarking densities affect the estimates and visualisations of mean and allometrically scaled surfaces. The performance of three landmark-driven semilandmarking approaches is assessed using two different surface mesh datasets with different degrees of variation and complexity: adult human head and ape cranial surfaces. Surfaces fitted to estimates of the mean and allometrically scaled landmark and semilandmark configurations arising from geometric morphometric analyses of these datasets are compared between semilandmarking approaches and different densities, as well as with those from warping to landmarks alone. We find that estimates of surface mesh shape (i.e., after re-semilandmarking and then re-warping) made with varying numbers of semilandmarks are generally consistent, while the warping of surfaces using landmarks alone yields surfaces that can be quite different to those based on semilandmarks, depending on landmark coverage and choice of template surface for warping. The extent to which these differences are important depends on the particular study context and aims. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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13 pages, 2480 KiB

Open AccessArticle

Energetic Implications of Morphological Changes between Fish Larval and Juvenile Stages Using Geometric Morphometrics of Body Shape

by Lorena Martinez-Leiva, José M. Landeira, Effrosyni Fatira, Javier Díaz-Pérez, Santiago Hernández-León, Javier Roo and Víctor M. Tuset

Animals 2023, 13(3), 370; https://doi.org/10.3390/ani13030370 - 21 Jan 2023

Cited by 3 | Viewed by 2472

Abstract

The fish body shape is a key factor that influences multiple traits such as swimming, foraging, mating, migrations, and predator avoidance. The present study describes the body morphological changes and the growth trajectories during the transformation from 24 to 54 days post-hatching in [...] Read more.

The fish body shape is a key factor that influences multiple traits such as swimming, foraging, mating, migrations, and predator avoidance. The present study describes the body morphological changes and the growth trajectories during the transformation from 24 to 54 days post-hatching in the golden grey mullet, Chelon auratus, using geometric morphometric analysis (GMA). The results revealed a decrease in morphological variability (i.e., morphological disparity) with the somatic growth. The main changes affected head size, elongation, and widening of the body. Given that this variability could affect the metabolism, some individuals with different morphologies and in different ontogenetic developmental stages were selected to estimate their potential respiration rate using the Electron Transport System (ETS) analysis. Differences were detected depending on the developmental stage, and being significantly smaller after 54 days post-hatching. Finally, a multivariate linear regression indicated that the specific ETS activity was partially related to the fish length and body shape. Thus, our findings emphasized the relevance of larval morphological variability for understanding the physiological processes that occur during the development. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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13 pages, 1419 KiB

Open AccessFeature PaperArticle

Head Shape Heritability in the Hungarian Meadow Viper Vipera ursinii rakosiensis

by Duarte Oliveira, Bálint Halpern, Fernando Martínez-Freiría and Antigoni Kaliontzopoulou

Animals 2023, 13(2), 322; https://doi.org/10.3390/ani13020322 - 16 Jan 2023

Viewed by 2224

Abstract

Understanding heritability patterns in functionally relevant traits is a cornerstone for evaluating their evolutionary potential and their role in local adaptation. In this study, we investigated patterns of heritability in the head shape of the Hungarian meadow viper (Vipera ursinii rakosiensis). [...] Read more.

Understanding heritability patterns in functionally relevant traits is a cornerstone for evaluating their evolutionary potential and their role in local adaptation. In this study, we investigated patterns of heritability in the head shape of the Hungarian meadow viper (Vipera ursinii rakosiensis). To this end, we used geometric morphometric data from 12 families composed of 8 mothers, 6 fathers and 221 offspring, bred in captivity at the Hungarian Meadow Viper Conservation Centre (Hungary). We separately evaluated maternal and paternal contributions to the offspring phenotype, in addition to additive genetic effects, all determined using a mixed animal model. Our results indicate a strong genetic and maternal contribution to head shape variations. In contrast, the paternal effects—which are rarely evaluated in wild-ranging species—as well as residual environmental variance, were minimal. Overall, our results indicate a high evolutionary potential for head shape in the Hungarian meadow viper, which suggests a strong contribution of this ecologically important trait in shaping the ability of this endangered species to adapt to changing conditions and/or habitats. Furthermore, our results suggest that maternal phenotypes should be carefully considered when designing captive breeding parental pairs for reinforcing the adaptive capacity of threatened populations, whereas the paternal phenotypes seem less relevant. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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11 pages, 2753 KiB

Open AccessArticle

Ecomorphology and Morphological Disparity of Caquetaia Kraussii (Perciformes: Cichlidae) in Colombia

by Jordan Hernandez, Amado Villalobos-Leiva, Adriana Bermúdez, Daniela Ahumada-C, Manuel J. Suazo, Margarita Correa, Angie Díaz and Hugo A. Benítez

Animals 2022, 12(23), 3438; https://doi.org/10.3390/ani12233438 - 06 Dec 2022

Cited by 3 | Viewed by 1765

Abstract

Understanding the interspecific morphological variability of Caquetaia kraussii (Perciformes: Cichlidae) between different localities in its distribution range is becoming essential, as this species constitutes a valuable resource for the economy and subsistence of the local human communities where it is endemic in Colombia [...] Read more.

Understanding the interspecific morphological variability of Caquetaia kraussii (Perciformes: Cichlidae) between different localities in its distribution range is becoming essential, as this species constitutes a valuable resource for the economy and subsistence of the local human communities where it is endemic in Colombia and Venezuela. In order to develop efficient farming and handling plans for this species, a deep understanding of the factors and mechanisms generating morphological variability is crucial. This study analyzes the morphological variability of C. kraussii by using geometric morphometrics in four localities distributed between the Dique and North channels, which are part of the Bolívar department in Colombia. Likewise, the effect of environmental variables such as temperature (T°), dissolved oxygen (OD) and pH on morphological variability was analyzed using a partial least squares approach. The results show that environmental stress has an influence on ~10% of the body shape of C. kraussii, whereas ~90% of the body shape is not directly influenced by environmental parameters, suggesting an effect from stress related to sexual dimorphism. Similarly, the analyses show shape variation among localities, mainly between populations of lotic environments and those of lentic environments. This morphological disparity seems to be subject to environmental and sexual stresses in the different localities. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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9 pages, 1706 KiB

Open AccessArticle

Morphological Differences between Sheep and Goat Calcanea Using Two-Dimensional Geometric Morphometrics

by Lluís Lloveras, Carme Rissech, Simon Davis and Pere M. Parés-Casanova

Animals 2022, 12(21), 2945; https://doi.org/10.3390/ani12212945 - 26 Oct 2022

Cited by 2 | Viewed by 1792

Abstract

The distinction between bones of sheep and bones of goats is a difficult issue in zooarchaeology. Several studies undertaken in the past to facilitate this task have relied upon both qualitative criteria and osteometry. Geometric morphometrics has proved to be a powerful tool [...] Read more.

The distinction between bones of sheep and bones of goats is a difficult issue in zooarchaeology. Several studies undertaken in the past to facilitate this task have relied upon both qualitative criteria and osteometry. Geometric morphometrics has proved to be a powerful tool to evaluate morphological differences in a rigorous and detailed manner. This study aims to analyse variations in the morphology of the calcaneum among sheep and goats based upon two-dimensional geometric morphometrics (GM). Twenty landmarks were selected on the surfaces of 79 calcanea (47 sheep and 32 goats) to calculate the principal components of shape variations among these specimens. Clear interspecific differences in the morphology of this bone were extracted. Most are located on the calcaneal tuber and neck, the sustentacular tali region, the articular surfaces of both the malleolus and the cubonavicular. Furthermore, the use of GM methods has enabled us to assess small but significant amounts of geometric variation that are difficult to measure using traditional morphometric techniques. They provide a new and useful perspective to what is already known in the published literature. Our results shed new light upon the possibility of the existence of qualitative features that may help to distinguish caprine breeds. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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12 pages, 3077 KiB

Open AccessArticle

Morphological Stasis in Time? A Triatoma brasiliensis brasiliensis Study Using Geometric Morphometrics in the Long Run

by Letícia Paschoaletto, Carolina Dale, Vanessa Lima-Neiva, Ana Laura Carbajal-de-la-Fuente, Jader de Oliveira, Hugo A. Benítez and Jane Costa

Animals 2022, 12(11), 1362; https://doi.org/10.3390/ani12111362 - 26 May 2022

Cited by 1 | Viewed by 1667

Abstract

Triatoma brasiliensis brasiliensis Neiva, 1911 is one of the most important vectors of Chagas disease in the Brazilian semiarid regions in the north-east. The risk imposed by T. b. brasiliensis to the human populations, due to frequent invasions and/or colonization of the domiciles, [...] Read more.

Triatoma brasiliensis brasiliensis Neiva, 1911 is one of the most important vectors of Chagas disease in the Brazilian semiarid regions in the north-east. The risk imposed by T. b. brasiliensis to the human populations, due to frequent invasions and/or colonization of the domiciles, demands constant monitoring and control actions as well as an understanding of its evolutionary process. In this context, the following research studies the pattern of shape adaptation over time using a large dataset from 102 years of specimen collections in order to identify the morphological plasticity of this vector in Brazil. This dataset was analyzed using geometric morphometrics tools and the timescale was divided into eight different groups, containing specimens from 1912 to 2014. Geometric morphometrics analysis showed an interesting morphological stasis in the wing shape of T. b. brasiliensis, which allowed us to understand the high capacity of adaptation to changes in climate condition through time, and the invasive status which Triatoma species have around the world. Moreover, these results showed novel findings as an interesting phenotypic pattern, with no modifications in more than 100 years, leading us to understand the shape evolution in Triatominae as a vector species of diseases. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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15 pages, 9294 KiB

Open AccessArticle

Insularity and Aridity as Drivers of Mandibular Disparity in Thylamys elegans (Waterhouse, 1839) from Populations of the Atacama Desert, Chile

by José I. Arriagada, Hugo A. Benítez, Frederick Toro, Manuel J. Suazo, Paulette Abarca, Jhoann Canto, Yerko A. Vilina and Franco Cruz-Jofré

Animals 2022, 12(9), 1179; https://doi.org/10.3390/ani12091179 - 04 May 2022

Viewed by 2240

Abstract

Island ecosystems differ in several elements from mainland ecosystems and may induce variations related to natural selection and patterns of adaptation in most aspects of the biology of an organism. Thylamys elegans (Waterhouse, 1839) is a marsupial endemic to Chile, distributed from Loa [...] Read more.

Island ecosystems differ in several elements from mainland ecosystems and may induce variations related to natural selection and patterns of adaptation in most aspects of the biology of an organism. Thylamys elegans (Waterhouse, 1839) is a marsupial endemic to Chile, distributed from Loa River to Concepción. Historically, three subspecies have been described: Thylamys elegans elegans, Thylamys elegans coquimbensis and Thylamys elegans soricinus. For this research, two morphometric approaches and a biomechanical model were used to compare the mandible shapes and biomechanics between two Chilean mouse opossum populations belonging to different subspecies: one from the coastal desert of Chile (T. e. coquimbensis) and the other from the central inland region (T. e. elegans). Additionally, mandibles of insular populations found in the Reserva Nacional Pinguino de Humboldt (RNPH)), from which the subspecies association is unknown, were also included. The results showed that insular populations have differences in mandibular shapes, sizes and biomechanical characteristics compared to continental populations, which may be related to environmental variables like aridity and vegetation cover, prey type, insularity effects and/or the founder effect on micromammals, apart from vicariance hypotheses and other selective pressures. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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10 pages, 1002 KiB

Open AccessArticle

Symmetry-Breaking Stabilities in Carapace Curvature on Testudo (Reptilia, Testudinidae)

by Pere M. Parés-Casanova, Joaquim Soler, Tania Buisán and Albert Martínez-Silvestre

Animals 2022, 12(4), 471; https://doi.org/10.3390/ani12040471 - 14 Feb 2022

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Abstract

The aim of this research was to contribute to the study of the doming geometry of Testudo carapace as an unstable point of equilibrium when animals are overturned. We performed this research using geometric morphometric using a sample of 64 Testudo individuals belonging [...] Read more.

The aim of this research was to contribute to the study of the doming geometry of Testudo carapace as an unstable point of equilibrium when animals are overturned. We performed this research using geometric morphometric using a sample of 64 Testudo individuals belonging to different species (T. hermannin = 30, T. graecan = 3, T. marginata n = 13 and T. horsfieldii n = 18), sexes and ages. A set of four sagittal landmarks (discrete homologous points) and 15 pairs of semi-landmarks, on the frontal doming of the carapace, were digitized on individual carapace pictures. Significative fluctuating asymmetry was detected, defined as small, completely random departures from bilateral symmetry, but much less than directional asymmetry, which appeared highly significative. Anti-symmetry did not appear. Carapace asymmetry was dominated by a clear right directionality. A possible biological speculation could be that this asymmetry more that easing the self-righting potential (“kinematic instability”, understood as the ability to self-right without effort), makes stable ventral turning difficult (“static stability”, understood as the ability to resist passively turning the body produced by destabilizing forces). This asymmetry is present among both sexes but more marked among males. An explanation for this sexually differentiated pattern could be the higher locomotion and the fight for mating in males, making them consequently more prone to losing their balance and falling on their back. These data may be useful in studying adaptative traits in Testudo species as well as establishing a seminal base for future studies. This research is the first attempt to explore a suitable method to assess doming asymmetry which could be useful in future, more extensive investigations, on a larger interspecific sample. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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10 pages, 2552 KiB

Open AccessArticle

Sex Determination in Japanese Quails (Coturnix japonica) Using Geometric Morphometrics of the Skull

by Tomasz Szara, Sokol Duro, Ozan Gündemir and İsmail Demircioğlu

Animals 2022, 12(3), 302; https://doi.org/10.3390/ani12030302 - 26 Jan 2022

Cited by 19 | Viewed by 99901

Abstract

The study investigated whether there is a morphological difference between the shape of the female and male quail’s skulls. For this purpose, 18 female and 21 male quails were used. After the skulls were obtained, their photographs were taken, and geometric analysis was [...] Read more.

The study investigated whether there is a morphological difference between the shape of the female and male quail’s skulls. For this purpose, 18 female and 21 male quails were used. After the skulls were obtained, their photographs were taken, and geometric analysis was performed. Dorsal (14 landmarks), caudal (8 landmarks), and ventral (13 landmarks) images of skulls were evaluated. As a result of the Principal Component Analysis (PCA), 28 principal components (PCs) were obtained for dorsal view, 16 PCs for caudal view, and 26 PCs for ventral view. PC1 (41.206%) for the caudal aspect explained the highest shape variation in terms of sex. It was seen that PC1 for dorsal view explained 33.046% and PC1 for ventral view explained 34.495% shape variation. For the dorsal view, the orbital pit of males was found to be deeper than females. The foramen magnum was narrower in female skulls. The lateral borders of the neurocranium were more pointed upwards in males. On ventral view, it was seen that male individuals had a wider skull in shape. Geometrically, it was determined that the male and female distinction was the best in the dorsal view. According to the dorsal view, only one male individual was found to be in the female group, and all other male individuals were completely separated from the females. After the dorsal view, the best distinction was seen ventrally. In the caudal examination, sexual discrimination was not fully seen. In this study, shape differences in quail’s skulls were examined between sexes, and shape differences were revealed geometrically. In addition to traditional morphometry studies, it is thought that geometric analysis studies will add a useful perspective to the literature. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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9 pages, 1741 KiB

Open AccessArticle

Exploratory Analysis of Color Forms’ Variability in the Invasive Asian Lady Beetle Harmonia axyridis (Pallas 1773)

by Darija Lemic, Ivana Pajač Živković, Matea Šuliček and Hugo A. Benítez

Animals 2021, 11(8), 2436; https://doi.org/10.3390/ani11082436 - 18 Aug 2021

Cited by 2 | Viewed by 2836

Abstract

The Asian ladybird (Harmonia axyridis Pallas), native to Asia, is one of the 100 most invasive species in the world and has spread worldwide. This study aimed to characterize color forms of H. axyridis in Croatia and to analyze the variability of [...] Read more.

The Asian ladybird (Harmonia axyridis Pallas), native to Asia, is one of the 100 most invasive species in the world and has spread worldwide. This study aimed to characterize color forms of H. axyridis in Croatia and to analyze the variability of wing shape between populations and indicated forms. Geometric morphometric methods were used to analyze a total of 129 left and right wings in males and 126 left and right wings in females of H. axyridis collected from four different sites in Croatia. The results show a significant difference in wing shapes between the studied forms. Each form had its own specific morphotype that likely originated under the influence of genetic changes in the species. This study demonstrates that the use of geometric morphometric analysis is effective in studying the variability in H. axyridis populations. As this study is the first of its kind, for further clarity, it is necessary to conduct additional studies on a larger number of sites and an equal number of individuals of all forms. Full article

(This article belongs to the Special Issue Geometric Morphometrics Applied to Biological Structures)

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