Study of Mandibular Shape in the Mouse

Lavelle, C.L.B.

doi:10.1159/000145803

Cited by 9 publications

(5 citation statements)

References 17 publications

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“…Possible reasons follow. Although no study to my knowledge has explicitly looked for species differences in ability to remodel, there appear to be differences among mouse strains in remodeling (Lavelle, 1983). 2) Chironomid larvae and flake food may differ nutritionally, thus inducing different magnitudes of change.…”

Section: Discussionmentioning

confidence: 99%

“…There is evidence for differences in the propensity to remodel for different bones, or types of bone in an individual (Crompton, unpubl.). Although no study to my knowledge has explicitly looked for species differences in ability to remodel, there appear to be differences among mouse strains in remodeling (Lavelle, 1983). These suggestions about remodeling are difficult to test because one must know that the strain regimes on a particular area of bone are the same, so that it is propensity to remodel and not differences in the remodeling stimulus that one is measuring.…”

Section: Discussionmentioning

confidence: 99%

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Plasticity of Jaw and Skull Morphology in the Neotropical Cichlids Geophagus brasiliensis and G. steindachneri

Wimberger¹

1991

Evolution

100

105

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I examined plasticity of jaw and skull morphology induced by feeding different diets in two species of the neotropical cichlid genus Geophagus. The two species possess different modes of development, which affect the size at which young begin feeding. I hypothesized that the difference in size at first feeding could lead to a difference in the amount of change inducible in the two species. The young of the substrate-spawning species, G. brasiliensis, which begin feeding at a smaller size, were predicted to be more plastic than those of the mouthbrooding species, G. steindachneri. The two diets used to induce differences were brine shrimp nauplii and chironomid larvae. Numerous measures of the jaw and skull differed significantly between groups fed the two diets but the amount of plasticity induced was small and would not present a problem for taxonomists. Contrary to my prediction, both the magnitude and pattern of plasticity induced in the two species was similar. Thus, mode of parental care and the size at which young begin feeding do not affect the degree of plasticity. Fish fed brine shrimp nauplii were longer in oral jaw region, but were shorter and shallower in the area behind the oral jaws. An additional group of G. brasiliensis was fed flake food to compare the results of this study to other studies. The differences in measures between fish fed brine shrimp diets and flake food diets were greater than those between fish fed brine shrimp and chironomid larvae. A possible role of plasticity for enhancing rather than retarding morphological evolution is discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Plasticity of Jaw and Skull Morphology in the Neotropical Cichlids Geophagus brasiliensis and G. steindachneri

Wimberger¹

1991

Evolution

100

105

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“…Morphological variability in mandibular form within and among taxa of mice and rats has been studied by a number of authors, including Festing (1973), Lavelle (1983), Lovell & Johnson (1983), Atchley (1983Atchley ( , 1990 a ) , Lovell et al ( I 984), Atchley et al (1984, 1985a, b, 1988, 199oa, b ) , Bailey (1985Bailey ( , 1986a, Moss (1988) and Cheverud et al ( I 990). These studies have shown that extensive variability exists in the dimensions of the mandible within taxa and that this variation within and among taxa has a large genetic component (Atchley, 1983, 199oa, Atchley et al, 1984, 1985a, b, 1988Cheverud et al, 1990).…”

Section: Morphological Divergence I N Mandible Form I N the Mousementioning

confidence: 99%

A Model for Development and Evolution of Complex Morphological Structures

1991

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How 'complex' or composite morphological structures like the mammalian craniomandibular region arise during development and how they are altered during evolution are two major unresolved questions in biology. Herein, we have described a model for the development and evolution of complex morphological structures. The model assumes that natural selection acts upon an array of phenotypes generated by variation in a variety of underlying genetic and epigenetic controlling factors. Selection refines the integration of the various morphogenetic components during ontogeny in order to produce a functioning structure and to adapt the organisms to differing patterns of environmental heterogeneity. The model was applied to the development and evolution of the mammalian mandible (which is used as a paradigm of complex morphological structures). The embryology of the mandible was examined in detail in order to identify the fundamental developmental units which are necessary to assemble the final morphological structure. The model is quite general since equivalent units exist for the development of many other biological structures. This model could be applied to many other developing morphological structures as well as other groups of organisms. For example, it can be applied to cell parameters during Drosophila development (Atchley, 1987). The model as discussed in this paper assumes that morphological changes in the mandible result from evolutionary changes in its underlying developmental units. The developmental units relate to characteristics of cellular condensations which are produced from the differentiation of embryonic neural crest cells. The developmental units include: the number of stem cells in preskeletal condensations (n), the time of initiation of condensation formation (t), the fraction of cells that is mitotically active within a condensation (f), the rate of division of these cells (r), and their rate of cell death (d). These units and their derivative structures are discussed in terms of types of tissue differentiation (chondrogenesis, osteogenesis, primary/secondary osteogenesis, intramembranous/endochondral ossification) and growth properties of major morphological regions of the mandible. Variation in these five units provides the developmental basis for ontogenetic and phylogenetic modification of mandibular morphology. We have discussed how these developmental units are influenced by (a) the cell lineage from which they arise, (b) epithelial-mesenchymal (inductive tissue) interactions, (c) regulation of cell differentiation, and (d) extrinsic factors such as muscles, teeth and hormones. Evidence was provided that variation in mandibular morphology is heritable, subject to modification by natural selection, and that divergence among different genetic stocks has apparently occurred through changes in these developmental units and their derivative structures.(ABSTRACT TRUNCATED AT 400 WORDS)

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“…When the environment changed sufficiently, the response was different among animals with different genotypes that were not different before the environmental change. (Lavelle, 1983) Siblings may often have similar malocclusions not just because of common genetic or environmental factors, but also because of their shared genetic factors affecting how they respond to the shared environmental factors. (King et al, 1993) However, none of these studies on the effect of environmental factors were focused on epigenetic modifications as a result of environmental factors influencing malocclusion.…”

Section: Genome Genotype Phenotype Modes Of Inheritance and Epigenmentioning

confidence: 99%