On homology

Roth, V. Louise

doi:10.1111/j.1095-8312.1984.tb00796.x

Cited by 203 publications

(155 citation statements)

References 27 publications

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“…Some authors argue that there is no essential difference between the two ideas, and that both can legitimately be seen as expressions of homology (e.g. Roth, 1984Roth, , 1988Ghiselin, 1976;Riedl, 1979). The opposite view, held by e.g.…”

Section: Taxic and Transformational Homologymentioning

confidence: 99%

Concepts and Tests of Homology in the Cladistic Paradigm

1991

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Abstract-Logical equivalence between the notions of homology and synapomorphy is reviewed and supported. So-called transformational homology embodies two distinct logical components, one related to comparisons among different organisms and the other restricted to comparisons within the same organism. The former is essentially hierarchical in nature, thus being in fact a less obvious form of taxic homology. The latter is logically equivalent to so-called serial homology in a broad sense (including homonomy, mass homology or iterative homology) -Of three tests of homology proposed to date (similarity, conjunction and congruence) only congruence serves as a test in the strict sense. Similarity stands at a basic level in homology propositions, being the source of the homology conjecture in the first place. Conjunction is unquestionably an indicator of non-homology, but it is not specific about the pairwise comparison where non-homology is present, and depends on a specific scheme of relationship in order to refute a hypothesis of homology. The congruence test has been previously seen as an application of compatibility analysis-However, congruence is more appropriately seen as an expression of strict parsimony analysis. A general theoretical solution is proposed to determine evolution of characters with ambiguous distributions, based on the notion of maximization of . homology propositions. According to that notion, ambiguous character-state distributions should be resolved by an optimization that maximizes reversals relative to parallelisms. Notions of homology in morphology and molecular biology are essentially the same. The present tendency to adopt different terminologies for the two sources of data should be avoided, in order not to obscure the fundamental uniformity of the concept of homology in comparative biology.

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Section: Taxic and Transformational Homologymentioning

confidence: 99%

Concepts and Tests of Homology in the Cladistic Paradigm

1991

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“…However, it also has long been clear that there is not a one-to-one correspondence between individual genes and traits. One response is to fall back on concepts other than the gene to explain trait persistence through time, including "essential genetic agreement" (Hubbs 1944), "continuity of information" (Van Valen 1982), and "sharing of pathways of development" (Roth 1984). I am attempting a different strategy that defines a developmentally relevant notion of "gene" (the DC gene) in order to explain the persistence of phenotypic attributes (phenes) through time.…”

Section: Parent-offspring Trait Homologymentioning

confidence: 99%

“…For example, it is commonly held that my fore and hind limbs are homologs in much the same way that my fore limbs are homologous to the wings of a chicken. The general thrust of the argument is that fore and hind limbs depend on the reutilization of largely (but not entirely) the same developmental program, in much the same way that shared genes make structures in different organisms homologous via continuity of information (Van Valen 1982;Roth 1984). How does the framework described here accommodate the phenomenon referred to as serial homology?…”

Section: Shared Features Of Developmental-causal Homology Conceptsmentioning

confidence: 99%

Developmental causation and the problem of homology

Baum¹

2013

Philosophy and Theory in Biology

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While it is generally agreed that the concept of homology refers to individuated traits that have been inherited from common ancestry, we still lack an adequate account of trait individuation or inheritance. Here I propose that we utilize a counterfactual criterion of causation to link each trait with a developmental-causal (DC) gene. A DC gene is made up of the genetic information (which might or might not be physically contiguous in the genome) that is needed for the production of the organismic attributes that comprise the trait. I argue that individuated traits-phenes-correspond to organismic features that are caused by DC genes. Using such an approach, we can define a DC map, which shows the relations between each pair of phenes and provides a succinct summary of genotype-phenotype relationships and phenotypic complexity. Phenes in parents and offspring are judged to be homologous if their DC genes are composed of orthologous genetic factors. When comparing more distantly related organisms, traits are homologous when linked by a chain of parent-offspring homologs along the path of ancestry that links the two organisms. There are three possible ways to deal with the potential for multiple equivalent DC genes: maximal, minimal, and consensus homology. Whereas maximal homology has limited utility, the other two approaches have value and can help to guide research at the intersection of evolution and development. IntroductionThe homology relation refers to the idea that different organisms of the same or different species share the same traits. For example, it is generally agreed that my middle finger nail and your middle finger nail are homologous with one other and with the hoof of a horse. As this example shows, homology does not require that the structures in question be identical in form or function. So what notion of "sameness" is connoted by homology? Darwin and subsequent biologists have generally agreed that the concept of homology relates in some way to descent from common ancestry (e.g., Lankaster 1870). A fingernail and a hoof are homologous because the common ancestor of a human and a horse had a structure that became modified to give rise to the human middle finger nail and the horse's hoof. Philos Theor Biol (2013) While the idea is simple, nailing down (no pun intended) the concept of homology has proved challenging, to say the least. While all agree that homology depends in some way on common ancestry, the manner of this dependence is far from clear. In particular, how can homology refer to the inheritance of traits from common ancestry when phenotypic traits are not passed on from generation to generation? Thankfully, we do not pass on our fingernails to our children by direct grafting! This paper is built on the premise that in order to get traction on homology, and put the concept to work in comparative biology, we first need to solve a much less studied conceptual problem: the nature of traits. When observing an organism we get the sense that it may be atomized into parts in some objecti...

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“…Their development, however, is usually internally constrained by the underlying genetic blueprint as well as morphogenetic processes that can be inherently self-regulatory. There, the 'biological homology' concept, as it has been referred to, is defined for anatomical structures that have a shared set of developmental constraints for their individualization [15,17]. As such, this form of homology mainly concerns phenotypes that result from complex regulatory interactions, rather than single-gene traits, such as colour variants [18,19].…”

Section: Introductionmentioning

confidence: 99%

Deep homology in the age of next-generation sequencing

Tschopp

Tabin

2017

Phil. Trans. R. Soc. B

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One contribution of 17 to a theme issue 'Evodevo in the genomics era, and the origins of morphological diversity'. The principle of homology is central to conceptualizing the comparative aspects of morphological evolution. The distinctions between homologous or non-homologous structures have become blurred, however, as modern evolutionary developmental biology (evo-devo) has shown that novel features often result from modification of pre-existing developmental modules, rather than arising completely de novo. With this realization in mind, the term 'deep homology' was coined, in recognition of the remarkably conserved gene expression during the development of certain animal structures that would not be considered homologous by previous strict definitions. At its core, it can help to formulate an understanding of deeper layers of ontogenetic conservation for anatomical features that lack any clear phylogenetic continuity. Here, we review deep homology and related concepts in the context of a gene expression-based homology discussion. We then focus on how these conceptual frameworks have profited from the recent rise of high-throughput nextgeneration sequencing. These techniques have greatly expanded the range of organisms amenable to such studies. Moreover, they helped to elevate the traditional gene-by-gene comparison to a transcriptome-wide level. We will end with an outlook on the next challenges in the field and how technological advances might provide exciting new strategies to tackle these questions.This article is part of the themed issue 'Evo-devo in the genomics era, and the origins of morphological diversity'.

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On homology

Cited by 203 publications

References 27 publications

Concepts and Tests of Homology in the Cladistic Paradigm

Concepts and Tests of Homology in the Cladistic Paradigm

Developmental causation and the problem of homology

Deep homology in the age of next-generation sequencing

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