The acquisition of conscience and Developmental Systems Theory

Summary Proponents of Developmental Systems Theory (DST) argue that it offers an alternative to current research programs in biology that are built on the historic disjunction between evolutionary and developmental biology. In this paper I illustrate how DST can be used to account for the acquisition of an important component of moral agency, conscience. Susan Oyama, a major proponent of DST, has set moral issues outside the compass of DST. Thus, I examine her reasons for restricting DST to non-moral matters, and argue that they are not decisive. On the positive side, I argue that DST not only is compatible with attempts to describe and explain moral agency but also aids us in understanding it. In particular, I show how DST can provide a fruitful perspective for viewing some significant current findings and theories in moral developmental psychology about the acquisition of conscience. The familiar dichotomies resisted by DST, those between genes and environment, inherited and acquired, innate and learned, and biological and cultural, have also plagued human developmental psychology, including moral development. By bringing a DST perspective to the study of moral development, I illustrate how a DST perspective might offer a promising way to reconceive that phenomenon, and provide some insights into how further work in understanding the development of moral agency might proceed. Thus, I hope to contribute to the current efforts of proponents of DST to integrate developmental and evolutionary considerations.     

Bridging the gap between developmental systems theory and evolutionary developmental biology

Many scientists and philosophers of science are troubled by the relative isolation of developmental from evolutionary biology. Reconciling the science of development with the science of heredity preoccupied a minority of biologists for much of the twentieth century, but these efforts were not corporately successful. Mainly in the past fifteen years, however, these previously dispersed integrating programmes have been themselves synthesized and so reinvigorated. Two of these more recent synthesizing endeavours are evolutionary developmental biology (EDB, or "evo-devo") and developmental systems theory (DST). While the former is a bourgeoning and scientifically well-respected biological discipline, the same cannot be said of DST, which is virtually unknown among biologists. In this review, we provide overviews of DST and EDB, summarize their key tenets, examine how they relate to one another and to the study of epigenetics, and survey the impact that DST and EDB have had (and in future should have) on biological theory and practice.     

Evolutionary developmental biology its roots and characteristics

The rise of evolutionary developmental biology was not the progressive isolation and characterization of developmental genes and gene networks. Many obstacles had to be overcome: the idea that all genes were more or less involved in development; the evidence that developmental processes in insects had nothing in common with those of vertebrates.Different lines of research converged toward the creation of evolutionary developmental biology, giving this field of research its present heterogeneity. This does not prevent all those working in the field from sharing the conviction that a precise characterization of evolutionary variations is required to fully understand the evolutionary process.Some evolutionary developmental biologists directly challenge the Modern Synthesis. I propose some ways to reconcile these apparently opposed visions of evolution. The turbulence seen in evolutionary developmental biology reflects the present entry of history into biology.     

以发育模块重复征用和整合为基础的进化创新机制

进化新征的起源和分化是进化发育生物学研究的核心问题。通过对多细胞生物早期发育调控机制的比较分析,发现亲缘关系较远的生物所共有的一些形态特征受保守的发育调控程序调节（深同源性）。许多创新性状的发生是基于对预先存在的基因或发育调控模块的重复利用和整合。发育基因调控网络在结构和功能上高度模块化,因此不仅可以通过模块拆分和重复征用改变发育程式,而且也增强了调控网络自身的进化力。研究基因调控网络和发育系统的进化动态将有助于更深入地认识生物演化过程中创新性状发生和表型进化的分子机制。     

Developmental quantitative genetic models of evolutionary change

Discussions about evolutionary change in developmental processes or morphological structures are predicated on specific quantitative genetic models whose parameters predict whether evolutionary change can occur, its relative rate and direction, and if correlated change will occur in other related and unrelated structures. The appropriate genetic model should reflect the relevant genetical and developmental biology of the organisms, yet be simple enough in its parameters so that deductions can be made and hypotheses tested. As a consequence, the choice of the most appropriate genetic model for polygenically controlled traits is a complex tissue and the eventual choice of model is often a compromise between completeness of the model and computational expediency. Herein, we discuss several developmental quantitative genetic models for the evolution of development and morphology. The models range from the classical direct effects model to complex epigenetic models. Further, we demonstrate the algebraic equivalency of the Cowley and Atchley epigenetic model and Wagner's developmental mapping model. Finally, we propose a new multivariate model for continuous growth trajectories. The relative efficacy of these various models for understanding evolutionary change in developmental and morphological traits is discussed. © 1994 Wiley-Liss, Inc.     

Developing the genotype-to-phenotype relationship in evolutionary theory: A primer of developmental features

For decades, there have been repeated calls for more integration across evolutionary and developmental biology. However, critiques in the literature and recent funding initiatives suggest this integration remains incomplete. We suggest one way forward is to consider how we elaborate the most basic concept of development, the relationship between genotype and phenotype, in traditional models of evolutionary processes. For some questions, when more complex features of development are accounted for, predictions of evolutionary processes shift. We present a primer on concepts of development to clarify confusion in the literature and fuel new questions and approaches. The basic features of development involve expanding a base model of genotype-to-phenotype to include the genome, space, and time. A layer of complexity is added by incorporating developmental systems, including signal-response systems and networks of interactions. The developmental emergence of function, which captures developmental feedbacks and phenotypic performance, offers further model elaborations that explicitly link fitness with developmental systems. Finally, developmental features such as plasticity and developmental niche construction conceptualize the link between a developing phenotype and the external environment, allowing for a fuller inclusion of ecology in evolutionary models. Incorporating aspects of developmental complexity into evolutionary models also accommodates a more pluralistic focus on the causal importance of developmental systems, individual organisms, or agents in generating evolutionary patterns. Thus, by laying out existing concepts of development, and considering how they are used across different fields, we can gain clarity in existing debates around the extended evolutionary synthesis and pursue new directions in evolutionary developmental biology. Finally, we consider how nesting developmental features in traditional models of evolution can highlight areas of evolutionary biology that need more theoretical attention.     

Phylogeny and evo-devo: characters, homology, and the historical analysis of the evolution of development

The concept of homology continues to attract more and more commentary. In systematic and evolutionary biology the meaning of homology as synapomorphic similarity inherited from a common ancestor has gained wide acceptance over the last three or four decades. In recent years, however, developmental biologists, in particular, have argued for a new approach to, and new definition for, homology that revolves around the desire to make it more process-oriented and more mechanistic. These efforts raise questions about the relationship between developmental and evolutionary biology as well as how the evolution of development is to be studied. It is argued in this paper that this new approach to homology seemingly decouples developmental biology from the study of the evolution of development rather than to facilitate that study. In contrast, applying the notion of historical, phylogenetic homology to developmental data is inherently comparative and therefore evolutionary.     

花、基因、禾本科

进化发育生物学的一个重要任务就是揭示形态多样性的分子基础,该领域的研究包含形态、形态发育相关基因和形态所属类群等三个要素。花/花序是进化发育生物学研究的首要对象,系统发育重建和个体发育剖析的结合将促进认知花的形态进化。发育相关基因的进化表现为等位基因遗传或表观遗传的突变,基因家族生与死的进化,不同基因组拥有独特的基因。运用形态学或序列分析方法很大程度揭示了禾本科植物花进化过程中的基因进化。试从学科问题、思路方法以及具体例子介绍植物进化发育生物学。     

花、基因、禾本科

进化发育生物学的一个重要任务就是揭示形态多样性的分子基础, 该领域的研究包含形态、形态发育相关基因和形态所属类群等三个要素。花/花序是进化发育生物学研究的首要对象, 系统发育重建和个体发育剖析的结合将促进认知花的形态进化。发育相关基因的进化表现为等位基因遗传或表观遗传的突变, 基因家族生与死的进化, 不同基因组拥有独特的基因。运用形态学或序列分析方法很大程度揭示了禾本科植物花进化过程中的基因进化。试从学科问题、思路方法以及具体例子介绍植物进化发育生物学。     

植物进化发育生物学的形成与研究进展

植物进化发育生物学是最近十几年来才兴起的一门学科, 它是进化发育生物学的主要分支之一。进化发育生物学的产生经历了进化生物学与胚胎学、遗传学和发育生物学的三次大的综合, 其历史可追溯到19世纪初冯.贝尔所创立的比较胚胎学。相关研究曾沉寂了近一个世纪, 直到20世纪80年代早期, 动物中homeobox基因被发现, 90年代初花发育的 ABC模型被提出, 加之对发育相关基因研究的不断深入, 才使基因型与表型联系了起来, 进而促进了进化发育生物学的飞速发展。目前进化发育生物学已成为21世纪生命科学领域的研究热点之一。本文详细阐述了进化发育生物学产生和发展的历程, 综述了最近十几年来植物进化发育生物学的主要研究进展。文中重点介绍了与植物发育密切相关的MADS-box基因在植物各大类群中的研究现状, 讨论了植物进化发育生物学领域的研究成果对花被演化、花对称性以及叶的进化等重要问题的启示。     

植物进化发育生物学的形成与研究进展

植物进化发育生物学是最近十几年来才兴起的一门学科,它是进化发育生物学的主要分支之一。进化发育生物学的产生经历了进化生物学与胚胎学、遗传学和发育生物学的三次大的综合,其历史可追溯到19世纪初冯.贝尔所创立的比较胚胎学。相关研究曾沉寂了近一个世纪,直到20世纪80年代早期,动物中homeobox基因被发现,90年代初花发育的ABC模型被提出,加之对发育相关基因研究的不断深入,才使基因型与表型联系了起来,进而促进了进化发育生物学的飞速发展。目前进化发育生物学已成为21世纪生命科学领域的研究热点之一。本文详细阐述了进化发育生物学产生和发展的历程,综述了最近十几年来植物进化发育生物学的主要研究进展。文中重点介绍了与植物发育密切相关的MADS-box基因在植物各大类群中的研究现状,讨论了植物进化发育生物学领域的研究成果对花被演化、花对称性以及叶的进化等重要问题的启示。     

How developmental is evolutionary developmental biology?

Evolutionary developmental biology (evo-devo) offers both an account of developmental processes and also new integrative frameworks for analyzing interactions between development and evolution. Biologists and philosophers are keen on evo-devo in part because it appears to offer a comfort zone between, on the one hand, what some take to be the relative inability of mainstream evolutionary biology to integrate a developmental perspective; and, on the other hand, what some take to be more intractable syntheses of development and evolution. In this article, I outline core concerns of evo-devo, distinguish theoretical and practical variants, and counter Sterelny's recent argument that evo-devo's attention to development, while important, offers no significant challenge to evolutionary theory as we know it. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evolutionary Novelty and the Evo-Devo Synthesis: Field Notes

Accounting for the evolutionary origins of morphological novelty is one of the core challenges of contemporary evolutionary biology. A successful explanatory framework requires the integration of different biological disciplines, but the relationships between developmental biology and standard evolutionary biology remain contested. There is also disagreement about how to define the concept of evolutionary novelty. These issues were the subjects of a workshop held in November 2009 at the University of Alberta. We report on the discussion and results of this workshop, addressing questions about (i) how to define evolutionary novelty and understand its significance, (ii) how to interpret evolutionary developmental biology as a synthesis and its relation to neo-Darwinian evolutionary theory, and (iii) how to integrate disparate biological approaches in general.     

Offerings from an urchin

There is a natural curiosity about how organisms give rise to offspring like themselves through a series of reproducible developmental events and how, once mature, these offspring mate and continue the process giving rise the next generation. In the mid-1800 s investigators started using gametes and embryos to explore this process. Although the observations and experimental approaches changed over time, embryologists and developmental biologists after them, sought understanding of development and inheritance through the study of gametes and embryos. It is argued here that in their quests to understand these processes embryologists made major conceptual advances that were seminal to the origins of genetics and to the origins of molecular biology. Furthermore these advances derived from the distinct perspective of those investigators with focused interest on the development of the organism. In this essay fundamental discoveries that originated with the sea urchin embryo as an experimental system are used to illustrate this position. The sea urchin has a long and uninterrupted history as a model organism that helped prepare the ground for the emergence of genetics and contributed important aspects to understanding of the central dogma of molecular biology. As molecular biology came of age new concepts and technology of the discipline were transformative for developmental biology and to this day the reciprocal inductive interactions between molecular biology and developmental biology continue to revitalize each other.     

Embryology and evolution 1920-1960: worlds apart?

During the early part of the 20th century most embryologists were skeptical about the significance of Mendelian genetics to embryological development. A few embryologists began to study the developmental effects of Mendelian genes around 1940. Such work was a necessary step on the path to modern developmental biology. It occurred during the time when the Evolutionary Synthesis was integrating Mendelian and population genetics into a unified evolutionary theory. Why did the first embryological geneticists begin their study at that particular time? One possible explanation is that developmental genetics was a potential avenue of alliance between embryology and evolutionary biology, two fields that had been separated since the 1890s. To assess this possible motive it is necessary to explore the methodological contrasts that obtained between embryology and both Mendelian-chromosomal genetics and neo-Darwinian evolutionary theory. Some of these contrasts persist to the present day.     

Michael Akam and the rise of evolutionary developmental biology

Michael Akam has been awarded the 2007 Kowalevsky medal for his many research accomplishments in the area of evolutionary developmental biology. We highlight three tributaries of Michael’s contribution to evolutionary developmental biology. First, he has made major contributions to our understanding of development of the fruit fly, Drosophila melanogaster. Second, he has maintained a consistent focus on several key problems in evolutionary developmental biology, including the evolving role of Hox genes in arthropods and, more recently, the evolution of segmentation mechanisms. Third, Michael has written a series of influential reviews that have integrated progress in developmental biology into an evolutionary perspective. Michael has also made a large impact on the field through his effective mentorship style, his selfless promotion of younger colleagues, and his leadership of the University Museum of Zoology at Cambridge and the European community of evolutionary developmental biologist.     

Functional evolutionary developmental biology (evo-devo) of morphological novelties in plants

The origin of morphological and ecological novelties is a long-standing problem in evolutionary biology.Understanding these processes requires investigation from both the development and evolution standpoints,which promotes a new research field called evolutionary developmental biology (evo-devo).The fundamental mechanism for the origin of a novel structure may involve heterotopy,heterochrony,ectopic expression,or loss of an existing regulatory factor.Accordingly,the morphological and ecological traits cont...     

The evolution of developmental mechanisms

Over the past two to three decades, developmental biology has demonstrated that all multicellular organisms in the animal kingdom share many of the same molecular building blocks and many of the same regulatory genetic pathways. Yet we still do not understand how the various organisms use these molecules and pathways to assume all the forms we know today. Evolutionary developmental biology tackles this problem by comparing the development of one organism to another and comparing the genes involved and gene functions to understand what makes one organism different from another. In this review, we revisit a set of seven concepts defined by Lewis Wolpert (fate maps, asymmetric division, induction, competence, positional information, determination, and lateral inhibition) that describe the characters of many developmental systems and supplement them with three additional concepts (developmental genomics, genetic redundancy, and genetic networks). We will discuss examples of comparative developmental studies where these concepts have guided observations on the advent of a developmental novelty. Finally, we identify a set of evolutionary frameworks, such as developmental constraints, cooption, duplication, parallel and convergent evolution, and homoplasy, to adequately describe the evolutionary properties of developmental systems.     

From Haeckel to event-pairing: the evolution of developmental sequences

Summary Development involves a series of developmental events, separated by transformations, that follow a particular order or developmental sequence. The sequence may in turn be arbitrarily subdivided into contiguous segments (developmental stages). We discuss the properties of developmental sequences. We also examine the differing analytical approaches that have been used to analyse developmental sequences in an evolutionary context. Ernst Haeckel was a pioneer in this field. His approach was evolutionary and he introduced the idea of sequence heterochrony (evolutionary changes in the sequence of developmental events). Despite the availability of detailed developmental data (e.g. Franz Keibel’s ‘Normal Tables’), Haeckel was unable to undertake a quantitative analysis of developmental data. This is now possible through computer-based analytical techniques such as event-pairing, which can extract important biological information from developmental sequences by mapping them onto established phylogenies. It may also yield data that can be used in phylogeny reconstruction, although the inherent ‘non-independence’ of the data may make this invalid. In future, the methods discussed here may be applied to the analysis of patterns of gene expression in embryos, or adapted to studying gene order on chromosomes.