The ontogenetic complexity of developmental constraints

Developmental constraint is a theoretically important construct bridging ontogenetic and evolutionary studies. We propose a new operationalization of this notion that exploits the unusually rich measurement structure of landmark data. We represent landmark configurations by their partial warps, a basis for morphospace that represents a set of localized features of form. A finding of developmental constraint arises from the interplay between age-varying means and age-specific variances in these subspaces of morphospace. Examination of variances and means in 16 ventral skull landmarks in the cotton rat S. fulviventer at ages 1, 10, 20, and 30 days yielded three types of developmental constraint: canalization (constraint to relatively constant form age by age); chreods (reduction of variance orthogonal to the mean trajectory over ages); and opposition (reduction of age-specific variance along the mean trajectory over ages). While canalization and chreodic constraints have been noted previously, the oppositional type of constraint appears novel. Only one of our characters, relative length and orientation of the incisive foramen, appears to be canalized. Although skull growth becomes increasingly integrated through ontogeny, our characters display a remarkable spatiotemporal complexity in patterns of variance reduction. The specific assortment of constraints observed may be related to the precociality of Sigmodon . We suggest that Waddington's diagrammatic presentation of the “epigenetic landscape” may be misleading in quantitative studies of developmental regulation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73980/1/j.1420-9101.1993.6050621.x.pd

Random walk and quantitative stratigraphical sequences

A sequence of digitized observations on short-normal resistivity determinations seems to show trend from higher to lower values. An appropriate statistical model proves it to have less range than expected on the distribution of its successive increments. On a two-tailed statistical procedure for testing deviations from a random walk, the series tends towards ‘stasis’ rather than trend. The random walk model is shown to be plausible for the problem considered.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73590/1/j.1365-3121.1992.tb00465.x.pd

The Structure Of Individual Variation In Miocene Globorotalia

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137454/1/evo05209.pd

Ontogeny Of Integrated Skull Growth In The Cotton Rat Sigmodon Fulviventer

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137530/1/evo00626.pd

Physical Properties of Biological Entities: An Introduction to the Ontology of Physics for Biology

As biomedical investigators strive to integrate data and analyses across spatiotemporal scales and biomedical domains, they have recognized the benefits of formalizing languages and terminologies via computational ontologies. Although ontologies for biological entities—molecules, cells, organs—are well-established, there are no principled ontologies of physical properties—energies, volumes, flow rates—of those entities. In this paper, we introduce the Ontology of Physics for Biology (OPB), a reference ontology of classical physics designed for annotating biophysical content of growing repositories of biomedical datasets and analytical models. The OPB's semantic framework, traceable to James Clerk Maxwell, encompasses modern theories of system dynamics and thermodynamics, and is implemented as a computational ontology that references available upper ontologies. In this paper we focus on the OPB classes that are designed for annotating physical properties encoded in biomedical datasets and computational models, and we discuss how the OPB framework will facilitate biomedical knowledge integration

The inappropriateness of conventional cephalometrics

1. 1. Cephalometric conventions today may have little basis in either biology or biometrics.2. 2. There is no theory of cephalometrics, only conventions which involve landmarks and straight lines only. These fail to capture the curving of form and its changes, exclude proper measures of size for bent structures, and misrepresent growth, portraying it as vector displacement rather than a generalized distortion.3. 3. Conventional cephalometric procedures misinform by fabrication of misleading geometric quantities, by camouflage, particularly of remodeling, by confusion about what is happening (analysis of rotations, treating shape separately from size, and registering angles on landmarks as vertices), and by subtraction as a representation of growth.4. 4. We suggest that the present systems offer little real hope of improvement sufficient to meet our needs in craniofacial growth research. We call attention to three possible techniques to be included in future cephalometric conventions: (1) tangents and curvatures, (2) Blum's medial axis ("skeleton"), and (3) biorthogonal grids.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23746/1/0000718.pd

On the cephalometrics of skeletal change

This essay introduces the general tensor analysis of skeletal change for landmark data. Consider first a single triangle of landmarks at two times. Joint changes in the lengths of its sides, or in the positions of its vertices according to some coordinate system, may be taken to specify a uniform deformation of the entire interior. The biorthogonal method expresses this by a pair of principal dilatations--maximum and minimum rates of change in length--along directions lying at 90 degrees in some orientation upon the triangle. No analysis of static form is involved in their calculation, which measures shape change without measuring shape. From this basic biorthogonal decomposition, we pass by a suitable averaging to descriptions of mean change in groups of diverse initial form and subsequently to explicit comparison of two mean changes, such as "treatment effect," all in the same parameters: two dilatations and an orientation. Schemes of more than three landmarks may be analyzed by reduction to triangles. I exemplify the method using data from Sheldon Baumrind's study of Angle Class II treatment effects. With respect to the growth observed in a "control" group of untreated Class II cases, both "cervical" (headgear) and "intraoral" (activator) appliances have the effect of compressing a facial polygon horizontally (parallel to S-N) by about 1 percent per year and extending it vertically (perpendicular to S-N) by about 1 percent per year. These effects are slightly larger for the cervical treatment, which also causes an increase in the distance from nasion to the line sella-ANS (that is, "rotates the face downward") by some 1 percent per year relative to the growth observed in the controls.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24101/1/0000358.pd