Morphological Integration of the Mandible in Yellow-necked Field mice: The Effects of B Chromosomes

Jojić, Vida; Blagojević, Jelena; Ivanović, Ana; Bugarski-Stanojević, Vanja; Vujošević, Mladen

doi:10.1644/06-mamm-a-019r1.1

Cited by 20 publications

(19 citation statements)

References 45 publications

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“…As previously stated (see Introduction), these chromosomal reorganizations can affect morphological covariation by modifying the linkage between alleles of loci influencing different mandibular traits, and by entailing the fixation of positively selected alleles. The progressively lower RV coefficients obtained in groups Rb (34)(35)(36)(37), Rb (31)(32)(33) and Rb (27)(28)(29)(30) could be due to the modification of the linkage between alleles. Given that metacentrics show the lowest chiasma frequency around the centromere [9], the formation of Rb translocations could progressively imply the emergence of new linkage groups around the centromere of the newly-formed metacentrics.…”

Section: Discussionmentioning

confidence: 92%

“…Regarding the pattern of shape changes associated with PC2 of the symmetric component, noticeable differences were detected between groups ( Figure 2A). In this case, groups 40St and Rb (27)(28)(29)(30) showed the comparatively most distinct patterns of shape variation ( Table 8). As for both PC1 and PC2 of the asymmetric component, some differences in the displacement direction of landmarks were detected between groups ( Figure 2B), which was supported by vector angles (Tables 7 and 8).…”

Section: Patterns Of Integrationmentioning

confidence: 87%

“…Procrustes ANOVAs conducted on each chromosomal group separately (40St, 40Rb, Rb (38)(39), Rb(34-37), Rb (31)(32)(33), Rb (27)(28)(29)(30)) consistently showed significant differences between individuals, regarding both shape and size variation. While directional asymmetry in shape was detected in all groups, directional asymmetry in size was only detected in group Rb(31-33) (see Additional file 1).…”

Section: Sources Of Shape and Size Variationmentioning

confidence: 90%

“…Size accounted for low-to-moderate fractions of this component (40St: 10.78%; 40Rb: 8.30%; Rb(38-39): 12.88%; Rb (34-37): 13.07%; Rb(31-33): 13.63%; Rb(27-30): 23.78%). The asymmetric component of shape variation showed a significant dependence on size asymmetry (P < 0.05) only in groups 40St, 40Rb and Rb (27)(28)(29)(30). On the whole, fairly low percentages of this component were predicted by size (40St: 2.41%; 40Rb: 4.08%; Rb(38-39): 1.94%; Rb (34-37): 1.76%; Rb(31-33): 1.08%; Rb(27-30): 3.56%).…”

Section: Allometrymentioning

confidence: 93%

“…Instead, scarce analyses have been performed on the intraspecific variation of the covariance structure of the mouse mandible in natural populations. Similarly, there is a shortage of studies on how changes in the covariance structure prompted by karyotypic variation can contribute to the processes of morphological evolution (but see [29,30]). Covariance structure is a population-level feature whose role in dictating the directions and pace of evolutionary transformations has long been discussed [31,32].…”

Section: Introductionmentioning

confidence: 99%

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Effect of chromosomal reorganizations on morphological covariation of the mouse mandible: insights from a Robertsonian system of Mus musculus domesticus

et al. 2014

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Introduction: Morphological integration and modularity depend on genetic covariation between traits, which emerges from pleiotropic effects of single loci and genetic linkage between loci. Since chromosomal reorganizations alter meiotic recombination, they might modify groups of linked genes and entail the fixation of new alleles with new pleiotropic effects. As a result, they could contribute to the intraspecific variation of the covariance structure of morphological traits. Although the mouse mandible has long been studied in terms of development and evolution, little is known about how its covariance structure varies in natural populations with chromosomal reorganizations. Consequently, here we analyzed the magnitude and patterns of morphological covariation of mandible shape in groups of mice with different karyotypes from a Robertsonian system of Mus musculus domesticus. Results: The organization of the mouse mandible into two main modules was confirmed in all chromosomal groups, since RV coefficients for the corresponding subdivision of landmarks were always significant. However, substantial variation in the magnitude of integration was detected between groups, especially when the effect of allometry was not removed. A significant positive correlation between differences in magnitude of integration of the symmetric component of shape and karyotypic distances between groups was detected when not correcting for size. Moreover, the degree of dependence of symmetric shape variation on size showed a negative association with the chromosome number and a positive association with the magnitude of integration. All groups showed similar patterns of morphological integration of the mandible, especially regarding the symmetric component of shape. However, the display of landmark displacements and the computation of vector angles highlighted some differences. In addition, distances between groups in terms of covariation matrices of the symmetric component were positively correlated with geographic distance. Conclusions: Robertsonian translocations do not alter the organization of the mouse mandible into two main modules, but do affect the magnitude of integration between them. This effect is mainly due to changes in the allometric relationship. In the 'Barcelona' Robertsonian system, geographically structured sources of variation seem to affect the patterns of integration by producing parallel variation in separate developmental pathways. Overall, our results suggest that Robertsonian translocations could play a role in intraspecific differentiation processes by producing changes in the covariance structure of morphological traits.

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Section: Discussionmentioning

confidence: 92%

Section: Patterns Of Integrationmentioning

confidence: 87%

Section: Sources Of Shape and Size Variationmentioning

confidence: 90%

Section: Allometrymentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Effect of chromosomal reorganizations on morphological covariation of the mouse mandible: insights from a Robertsonian system of Mus musculus domesticus

et al. 2014

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Genetic differentiation in populations of the yellow‐necked mouse, Apodemus flavicollis, harbouring B chromosomes in different frequencies

et al. 2012

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Two alternative models are used to explain maintenance of polymorphism of B chromosomes (Bs) in populations of a great number of species. The parasitic model suggests deleterious effects of Bs on fitness of carriers, while the heterotic model assumes that, in the absence of drive, equilibrium is produced by beneficial effects of Bs at low numbers. In order to determine the potential contribution of Bs to genetic differentiation and diversity, four populations of Apodemus flavicollis, differing in frequency of Bs (from 0.23 to 0.38) and settled in ecologically different habitats, were analyzed by 471 AFLP markers. Although numerous loci were demonstrated to be population specific, none of them was associated with individuals with Bs. AMOVA showed that the presence of Bs does not affect population differentiation, pointing to greater genetic similarity of Bs to A chromosomes. The greatest genetic diversity (0.241) was found in the population settled in optimal conditions for this species featured by the lowest frequency of animals with Bs (0.23). We found that the majority of loci marked as loci under directional selection, are characteristic of either a population with lower or one with a higher frequency of Bs. Several loci detected as outliers were associated with environmental variables that could directly and/or indirectly influence population dynamics of A. flavicollis. Thus, we suggest that the different frequency of Bs carriers in populations is related to adaptive differentiation to diverse habitats, which is in accordance with the heterotic model of Bs maintenance.

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Building Developmental Integration into Functional Systems: Function-Induced Integration of Mandibular Shape

2008

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The mammalian mandible is a developmentally modular but functionally integrated system. Whether morphological integration can evolve to match the optimal pattern of functional integration may depend on the developmental origin of integration, specifically, on the role that direct epigenetic interactions play in shaping integration. These interactions are hypothesized to integrate modules and also to be highly conservative, potentially constraining the evolution of integration. Using the fox squirrel (Sciurus niger) mandible as a model system, we test five a priori developmental hypotheses that predict mandibular integration and we also explore for correlations between shapes of mandibular regions not anticipated by any of the developmental models. To determine whether direct epigenetic interactions are highly conserved in rodents, we examine the correlation structure of fluctuating asymmetry, and compare integration patterns between fox squirrels and prairie deer mice (Peromyscus maniculatus bairdii). In fox squirrels, we find a correlation structure unanticipated by all a priori developmental models: adjacent parts along the proximodistal jaw axis are correlated whereas more distant ones are not. The most notable exception is that the shape of the anterior incisor alveolus is correlated with the shape of the ramus (FA component) or coronoid (symmetric component). Those exceptions differ between species; in prairie deer mice, the molar alveolus is connected to more parts, and the incisor alveolus to fewer, than in fox squirrels.

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Morphological Integration of the Mandible in Yellow-necked Field mice: The Effects of B Chromosomes

Cited by 20 publications

References 45 publications

Effect of chromosomal reorganizations on morphological covariation of the mouse mandible: insights from a Robertsonian system of Mus musculus domesticus

Effect of chromosomal reorganizations on morphological covariation of the mouse mandible: insights from a Robertsonian system of Mus musculus domesticus

Genetic differentiation in populations of the yellow‐necked mouse, Apodemus flavicollis, harbouring B chromosomes in different frequencies

Building Developmental Integration into Functional Systems: Function-Induced Integration of Mandibular Shape

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