[ Scott F. Gilbert, John M. Opitz, and Rudolf A. Raff (1996), “Resynthesizing Evolutionary and Developmental Biology”, Developmental Biology 173, pp. 357-372. ]
1. Introduction: The Genetic Redefinition of Evolution and Eclipse of Macroevolution and Homology
2. Genetic redefining of experimental embryology: Eclipse of morphogenetic field
3. Three Re-discoveries
3.1. The Rediscovery of Macroevolution
3.2. The Rediscovery of Homology
3.3. The Rediscovery of Morphogenetic field
4. Summary
5. Coda
1. Introduction: The Genetic Redefinition of Evolution and Eclipse of Macroevolution and Homology
357-359
- “The Rise of Genetics”
- 유전학(genetics)은 발생학(embryology)을 대체하고 진화학을 정리함.
- 유전학은 진화를 자연사(natural history)에서 과학으로 만듦.(change in gene frequency)
- Causality of the replacement of embryology by genetics
1. Macroevolution completely explainable by process of microevolution
(macroevolution : no status of its own)
2. Notion of homology (population genetic approach to evolution)
-> Darwin used homologies to indicate common descendent
2. Genetic redefining of experimental embryology: Eclipse of morphogenetic field
359-360
- 형태발생장(morphogenetic field): Basic paradigm of embryology
- Limb transplantation experiment of Harrison
해리슨은 이를 “Self-differentiating equipotential system”라고 부름
-> If undetermined cells or tissues were introduced into the field domain, they became organized and incorporated into the limb
- transplantation -> a limb
- cut in half -> two limbs
- graft together -> a normal limb
-> Web of interactions
: any cell was defined by its position within its respective field
-> informational and regional relationship
Paul Weiss (1939), “Principles of Development”
Gradient field
360-
- What destroyed the morphogenetic field? Nothing (eclipsed, ignored)
- Rather, 형태발생장은 무시되었음.
(1) biochemical technique not good enough
(2) decline of funding for biological science
(3) rise of genetics with its alternative program for development
- Embryology redefining as studying changes in gene expression
(embryogenesis = cell differentiation = differential protein synthesis)
-> embryology & evolution were given new, genotypic, definitions
- De Robertis and colleagues (1991)는 형태발생장이 문헌에서 사라졌다고 주장함.
추상적이고 거의 형이상학적이고, 실험에서만 드러날 수 있는 기술이기 때문
- Oppenheimer (1966)
-> techniques to analyze them had not yet appeared
-> eclipsed by genetic explanation of development (fields not needed)
3. Three Re-discoveries
361-362
- Microevolutionary changes in gene frequency (survival, not arrival)
: 파충류에서 포유류, 어류에서 양서류로의 전환을 설명할 수 없음
- Reexamining of Modern Synthesis -> re-discoveries in modern biology
: macroevolution, homology, morphogenetic field (New Synthesis)
- Developmentally oriented synthesis
: 소진화 뿐 아니라 대진화도 설명가능하게 함
- All changes important in evolution are alterations in development
Evolution involves heritable changes of development
One-toed horse derived from five-toed ancestor
Changes have occurred in the development of the limb Cartilage cells
Functional Biology = anatomy, physiology, cell biology, gene expression
Developmental Biology = δ [functional biology]/δt
Evolutionary Biology = δ [developmental biology]/δt
(Gilbert and Faber, 1996)
3.1. The Rediscovery of Macroevolution
362
- Attempts to decouple microevolution from macroevolution were either ignored or marginalized.
- Macroevolution : autonomous entity (Gould(1972), Stenley(1979))
- Gould (1982)
-> microevolutionary theory: not wrong or inadequate, but incomplete
-> punctuated equilibrium: bring to light the question of autonomy of macroevolution
- Molecular studies (King and Wilson, 1975)
-> similarly pointing to “evolution at two levels”
-> one molecular, the other morphological
# two areas (대진화 & 소진화) autonomous,
# microevolutionary events만으로 macroevolutionary process를 설명할수 없음
3.2. The Rediscovery of Homology
- Gould and Lewontin (1979) “The Spandrels of San Marco”
-> the idea of developmental homology reasserted
- Heterochrony (changes in the relative timing of developmental events) & Allometry (differential growth of parts)
-> Gould는 어떻게 발생학적 변화들이 빠른 속도로 대진화적인 새로움을 만들어낼 수 있는지 증명하기 위해 이 기작들을 사용
- Homology of process
-> goes into mechanisms of development
-> concerns similarities of dynamic interactions
- Homologous recombination to functionally delete homeotic genes:
- controlled formation of anterior-posterior axis
- produced atavistic changes
- Comparative study of Hoxgene clusters has become a major approach in clarifying the evolution of all metazoa(except perhaps the sponges)
3.3. The Rediscovery of Morphogenetic field
- Homology of process : occur within fields, 특정한 세포들의 집합
- De Robertis et al (1991)
: homeobox genes play role in initiating and organizing fields
- gradients of proteins
induce specific proteins production at specific sites
establish polar axes of organs
- The interactions in fields : not identified
-> homologous pathways of development : insight into how the fields are established and maintained
- Rediscovery가 Clsassical 개념들의 약점을 잘 보완 하고 있는가?
Rediscovery에 약점은 없는가?
Macroevolution은 autonomous한가, 그렇다면 그 증거는?
Classic morphogenetic field 와 Rediscovery의 차이점들은 Modern synthesis를 대체할 수 있는가?
Some of the molecular interactions
by which limb bud formation and growth are initiated and maintained
4. Summary
5. Coda
(2023.08.03.)
