Size and Shape Variation of Two Freshwater Crabs in Argentinean Patagonia: The Influence of Sexual Dimorphism, Habitat, and Species Interactions

Much of the morphological diversity in nature−including among sexes within a species−is a direct consequence of variation in size and shape. However, disentangling variation in sexual dimorphism for both shape (SShD), size (SSD) and their relationship with one another remains complex. Understanding how genetic variation influences both size and shape together, and how this in turn influences SSD and SShD is challenging. In this study we utilizeDrosophilawing size and shape as a model system to investigate how mutations influence size and shape as modulated by sex. Previous work has demonstrated that mutations in Epidermal Growth Factor Receptor (EGFR) and Transforming Growth Factor - β (TGF-β) signaling components can influence both wing size and shape. In this study we re-analyze this data to specifically address how they impact the relationship between size and shape in a sex-specific manner, in turn altering the pattern of sexual dimorphism. While most mutations influence shape overall, only a subset have a genotypic specific effect that influences SShD. Furthermore, while we observe sex-specific patterns of allometric shape variation, the effects of most mutations on allometry tend to be small. We discuss this within the context of using mutational analysis to understand sexual size and shape dimorphism.

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Sexual Dimorphism and Morphological Modularity in Acanthoscelides obtectus (Say, 1831) (Coleoptera: Chrysomelidae): A Geometric Morphometric Approach

Insects ◽

10.3390/insects12040350 ◽

2021 ◽

Vol 12 (4) ◽

pp. 350

Author(s):

Sanja Budečević ◽

Uroš Savković ◽

Mirko Đorđević ◽

Lea Vlajnić ◽

Biljana Stojković

Keyword(s):

Sexual Dimorphism ◽

Reproductive Function ◽

Morphological Integration ◽

Stabilizing Selection ◽

Shape Variation ◽

Acanthoscelides Obtectus ◽

Geometric Morphometric ◽

Size And Shape ◽

Acanthoscelides Obtectus Say ◽

Functional Hypothesis

Sexual dimorphism and specific patterns of development contribute in a great manner to the direction and degree of the sexual differences in body size and shape in many insects. Using a landmark-based geometric morpohometrics approach, we investigated sex-specific morphological size and shape variation in the seed beetle, Acanthoscelides obtectus. We also tested the functional hypothesis of the two morphological modules—thorax and abdomen in both sexes. Female-biased sexual dimorphism in size was shown, while differences in shape were reflected in the wider thorax and abdomen and shorter abdomen in females in comparison to males. The functional hypothesis of a two-module body was confirmed only in females before correction for size, and in both sexes after the allometry correction. Our results indicate that reproductive function has the central role in forming the patterns of modularity. We hypothesize that high morphological integration of the abdomen in females results from intense stabilizing selection, while the more relaxed integration in males is driven by the higher intensity of sexual selection.

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Intraspecific morphological variation of the scorpionfly Dicerapanorpa magna (Chou) (Mecoptera: Panorpidae) based on geometric morphometric analysis of wings

Contributions to Zoology ◽

10.1163/18759866-08501001 ◽

2016 ◽

Vol 85 (1) ◽

pp. 1-11 ◽

Cited By ~ 3

Author(s):

Mei Liu ◽

Na Ma ◽

Bao-Zhen Hua

Keyword(s):

Sexual Dimorphism ◽

Morphometric Analysis ◽

Divergence Time ◽

Wing Size ◽

Shape Variation ◽

Geometric Morphometric ◽

Size And Shape ◽

Geometric Morphometric Analysis ◽

Different Populations ◽

Intraspecific Morphological Variation

Wing shape variation was investigated between the sexes and among four populations of the scorpionfly Dicerapanorpa magna (Chou, 1981) endemic to the Qin-Ba Mountains area, China through the landmark-based geometric morphometric approach. The results show that sexual dimorphism exists both in wing size and shape in D. magna. Significant differences exist in female wing size and shape among D. magna populations. The possible reasons of the wing variation are discussed based on the divergence time of D. magna in combination with the tectonic and climatic events in the Qin-Ba Mountains during the late Miocene-Pleistocene period. Whether reproductive isolation exists between different populations needs further research.

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Inter- and intraspecific variation in the Artibeus species complex demonstrates size and shape partitioning among species

PeerJ ◽

10.7717/peerj.11777 ◽

2021 ◽

Vol 9 ◽

pp. e11777

Author(s):

Brandon P. Hedrick

Keyword(s):

Species Complex ◽

Niche Partitioning ◽

Fruit Size ◽

Interspecific Variation ◽

Cranial Morphology ◽

Foraging Strategies ◽

Shape Variation ◽

Size And Shape ◽

Ecological Resources ◽

Artibeus Lituratus

Neotropical leaf-nosed bats (family Phyllostomidae) are one of the most diverse mammalian families and Artibeus spp. is one of the most speciose phyllostomid genera. In spite of their species diversity, previous work on Artibeus crania using linear morphometrics has uncovered limited interspecific variation. This dearth of shape variation suggests that differences in cranial morphology are not contributing to niche partitioning across species, many of which are often found in sympatry. Using two-dimensional geometric morphometric methods on crania from eleven species from the Artibeus species complex, the current study demonstrates substantial cranial interspecific variation, sexual size and shape dimorphism, and intraspecific geographic variation. The majority of species were shown to have a unique size and shape, which suggests that each species may be taking advantage of slightly different ecological resources. Further, both sexual size and shape dimorphism were significant in the Artibeus species complex. Male and female Artibeus are known to have sex specific foraging strategies, with males eating near their roosts and females feeding further from their roosts. The presence of cranial sexual dimorphism in the Artibeus species complex, combined with previous work showing that different fruit size and hardness is correlated with different cranial shapes in phyllostomids, indicates that the males and females may be utilizing different food resources, leading to divergent cranial morphotypes. Additional field studies will be required to confirm this emergent hypothesis. Finally, significant geographical shape variation was found in a large intraspecific sample of Artibeus lituratus crania. However, this variation was not correlated with latitude and instead may be linked to local environmental factors. Additional work on ecology and behavior in the Artibeus species complex underlying the morphological variation uncovered in this study will allow for a better understanding of how the group has reached its present diversity.

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Consumer sexual dimorphism promotes coexistence among competing resources

10.1101/634782 ◽

2019 ◽

Author(s):

Stephen P. De Lisle ◽

Gonzalo Hernando ◽

Daniel I. Bolnick

Keyword(s):

Sexual Dimorphism ◽

Species Interactions ◽

Natural Populations ◽

Salient Feature ◽

Apparent Competition ◽

Species Variation ◽

Ecological Communities ◽

Key Factor ◽

Classical Models ◽

Resource Dynamics

AbstractWithin-species variation is a salient feature of natural populations, of substantial importance for species interactions. However, the community consequences of sexual dimorphism, one of the most ubiquitous sources of within-species variance, remains poorly understood. Here, we extend classical models of consumer-resource dynamics to explore the ecological consequences of consumer sexual dimorphism. We show that sexual dimorphism in consumer attack rates on two different resource species promotes coexistence between those resources, mitigating the effects of both apparent competition and direct interspecific competition. Consumer sexual dimorphism can prevent exclusion of a resource with inferior growth rates because reduction in any of the two resources reduces consumer density, generating negative frequency dependence that stabilizes coexistence between resources. Our work highlights ecological sex differences as a potentially key factor governing the assembly of ecological communities, illustrating that the specific source of within-species variance can have important implications for community ecology.

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A simple and rapid technique for surveying size and shape variation in desmids and diatoms

British Phycological Journal ◽

10.1080/00071617100650251 ◽

1971 ◽

Vol 6 (2) ◽

pp. 231-233 ◽

Cited By ~ 6

Author(s):

P.A. Tyler

Keyword(s):

Shape Variation ◽

Rapid Technique ◽

Size And Shape

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The Cheilosia canicularis group (Diptera: Syrphidae): species delimitation and evolutionary relationships based on wing geometric morphometrics

Zootaxa ◽

10.11646/zootaxa.1825.1.4 ◽

2008 ◽

Vol 1825 (1) ◽

pp. 40 ◽

Cited By ~ 12

Author(s):

JASMINA LUDOŠKI ◽

LJUBINKA FRANCUSKI ◽

ANTE VUJIĆ ◽

VESNA MILANKOV

Keyword(s):

Sequence Data ◽

Balkan Peninsula ◽

Wing Shape ◽

Canonical Variate ◽

Wing Size ◽

Shape Variation ◽

Geometric Morphometric ◽

Mahalanobis Distances ◽

Size And Shape ◽

Upgma Cluster Analysis

A landmark-based geometric morphometric approach was used to assess differences in the size and shape of wing among/within three species of the Cheilosia canicularis group (Diptera: Syrphidae): C. canicularis, C. himantopus and C. orthotricha. Wing size and shape variation was observed from 25, 176 and 41 specimens of C. canicularis, C. himantopus and C. orthotricha, respectively, collected from six localities on the Balkan Peninsula. Significant differences in wing size were obtained among the analysed species and canonical variate analysis showed that wing shape was sufficiently different to allow the correct classification of 73% individuals of C. canicularis, 80% of C. orthotricha and 94% of C. himantopus, and clear delimitation of the species pairs C. canicularis/C. orthotricha and C. himantopus/C. orthotricha. In all analysed species, the consistent sex dimorphism in wing shape was observed indicating that female specimens had shorter and broader wings than males. The UPGMA cluster analysis based on squared Mahalanobis distances revealed close accordance with previously published phylogenetic relationships of these species indicated by allozyme and DNA sequence data analysis. Our results suggested that wing parameters contain useful information in quantification phenotypic variation and identification of species in this challenging group for taxonomy and systematics.

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Sexual dimorphism in the size and shape of the raptorial pedipalps of Giant Whip Spiders (Arachnida: Amblypygi)

Journal of Zoology ◽

10.1111/jzo.12726 ◽

2019 ◽

Vol 310 (1) ◽

pp. 45-54

Author(s):

C.J. McLean ◽

R.J. Garwood ◽

C.A. Brassey

Keyword(s):

Sexual Dimorphism ◽

Size And Shape

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A Geometric Morphometric Assessment of Hand Shape and Comparison to the 2D:4D Digit Ratio as a Marker of Sexual Dimorphism

Twin Research and Human Genetics ◽

10.1017/thg.2013.5 ◽

2013 ◽

Vol 16 (2) ◽

pp. 590-600 ◽

Cited By ~ 3

Author(s):

Paul G. Sanfilippo ◽

Alex W. Hewitt ◽

Jenny A. Mountain ◽

David A. Mackey

Keyword(s):

Sexual Dimorphism ◽

Geometric Morphometrics ◽

Shape Analysis ◽

Twin Studies ◽

Analytical Techniques ◽

Shape Variation ◽

Geometric Morphometric ◽

Hand Shape ◽

Physical Traits ◽

Biological Shape

Twin studies are extremely useful for investigating hypotheses of genetic influence on a range of behavioral and physical traits in humans. Studies of physical traits, however, are usually limited to size-related biological characteristics because it is inherently difficult to quantify the morphological counterpart – shape. In recent years, the development of geometry-preserving analytical techniques built upon multivariate statistical methodologies has produced a new discipline in biological shape analysis known as geometric morphometrics. In this study of hand shape analysis, we introduce the reader already familiar with the field of twin research to the potential utility of geometric morphometrics and demonstrate the cross-discipline applicability of methods. We also investigate and compare the efficacy of the 2D:4D ratio, a commonly used marker of sexual dimorphism, to the fully multivariate approach of shape analysis in discriminating between male and female sex. Studies of biological shape variation utilizing geometric morphometric techniques may be completed with software freely available on the Internet and time invested to master the small learning curve in concepts and theory.

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