6 found
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  1. The Concept of Evenness/unevenness: Less Evenness or More Unevenness?Elizabeth M. Gillet & Hans-Rolf Gregorius - 2021 - Acta Biotheoretica 70 (1):1-28.
    While evenness is understood to be maximal if all types are represented equally, its opposite, maximal unevenness, either remains conceptually in the dark or is conceived as the type distribution that minimizes the applied evenness index. The latter approach, however, frequently leads to conceptual inconsistency due to the fact that the minimizing distribution is not specifiable or is monomorphic. The state of monomorphism, however, is indeterminate in terms of its evenness/unevenness characteristics. Indeed, the semantic indeterminacy also shows up in the (...)
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  2.  41
    A single-locus model of speciation.Hans-Rolf Gregorius - 1992 - Acta Biotheoretica 40 (4):313-319.
    The crucial phase of speciation is argued to be the evolution of mating cross-incompatibility (prezygotic incompatibility) between the genotypes distinguishing the prospective species populations. Based on this idea, a single-locus model of speciation is presented, which is shown to be biologically plausible and may help to settle the controversy as to the biological significance of single-locus modes of speciation. The model involves three alleles, two of which characterize in homozygous state the prospective species populations and in heterozygous state their hybrids. (...)
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  3.  27
    The Analysis of Association Between Traits When Differences Between Trait States Matter.Hans-Rolf Gregorius - 2011 - Acta Biotheoretica 59 (3):213-229.
    Because of their elementary significance in almost all fields of science, measures of association between two variables or traits are abundant and multiform. One aspect of association that is of considerable interest, especially in population genetics and ecology, seems to be widely ignored. This aspect concerns association between complex traits that show variable and arbitrarily defined state differences. Among such traits are genetic characters controlled by many and potentially polyploid loci, species characteristics, and environmental variables, all of which may be (...)
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  4.  26
    Differentiation between populations and its measurement.Hans-Rolf Gregorius - 1996 - Acta Biotheoretica 44 (1):23-36.
    When applied to a family of sets, the term differentiation designates a measure of the totality of those members which appear in only one of the sets. This basic set theoretic concept involves the formation of intersections, unions, and complements of sets. However, populations as special kinds of sets may share types, but they do not share the carriers of these types; intersections of different populations are thus always empty. The resulting conceptual dilemma is resolved by considering the joint representation (...)
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  5.  17
    The isolation principle of clustering: Structural characteristics and implementation.Hans-Rolf Gregorius - 2006 - Acta Biotheoretica 54 (3):219-233.
    The isolation principle rests on defining internal and external differentiation for each subset of at least two objects. Subsets with larger external than internal differentiation form isolated groups in the sense that they are internally cohesive and externally isolated. Objects that do not belong to any isolated group are termed solitary. The collection of all isolated groups and solitary objects forms a hierarchical (encaptic) structure. This ubiquitous characteristic of biological organization provides the motivation to identify universally applicable practical methods for (...)
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  6.  19
    Measuring association between two traits.Hans-Rolf Gregorius - 1998 - Acta Biotheoretica 46 (2):89-98.
    A measure of association is introduced that is based on a conceptual rather than a model approach in order to ensure its broad applicability. The basis of the concept involves two variables or traits and of members of a population. The association of the -state with the -state is measured by the degree to which members of given -state share their -state. This formulation yields an index of association, which is applicable to all categories of traits, including discontinuous and continuous (...)
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