The proximate-ultimate distinction can be given an epistemic or ontological reading. This epistemic reading includes that how questions cannot be addressed by explanations citing ultimate causes i.
Second, authors have interpreted this distinction as one between different ontological classes of causes working in ontogenetic and phylogenetic processes Laland et al.
Despite this lack of agreement this framework has been applied in various fields, from evolutionary biology E. Especially in evolutionary biology it has contributed to mainstream causal reasoning for a long time, even among evolutionary biologists interested in developmental processes see, e. There has been constant criticism of the proximate-ultimate distinction since even before Mayr , and against its underlying idea to downgrade the explanatory or causal relevance of development to evolution.
More recently, the discussion of this issue gained pace through new findings in fields such as epigenetics, evo-devo and niche construction theory Thierry ; Laland et al. Paradigmatic feedback cases are niche construction behaviors of organisms that modify their environments and thus shape natural selection pressures working on them.
In other words, reciprocal causation holds that organisms are not only effects of adaptive processes, but also causal starting points of evolutionary trajectories. It highlights the important role of development for evolution. Against this new approach, scholars have argued that reciprocal causation does, in fact, not pose any conceptual challenges for evolutionary biology, as it has been included since quite some time ago in the field Svennson A true challenge, however, is to develop this idea into a methodologically sound framework that allows studying and modeling complex non-linear organism-environment relations.
More generally, it has been requested that advocates of this approach should provide more conceptual clarifications on what reciprocal causation actually is supposed to mean Buskell Besides distinguishing development and evolution in a qualitative manner as proximate and ultimate causal processes, a less common attempt is to quantitatively distinguish or relate the two. Here, especially distinctions based on the rates or time scales on which different developmental and biological processes occur have been made see the entry levels of organization in biology.
For example, Conrad H. Waddington developed a hierarchical model of time scales that includes biochemical processes on lower molecular levels of organization with a faster rate, medium paced processes of development on a medium level, and evolutionary processes on higher levels with a slower rate.
According to such a view, evolutionary processes are simply processes occurring with a different rate and thus at a different level than developmental ones. Thus, they differ gradually rather than in kind. In addition, time-scale or size-scale conceptualizations have been applied for developing methodologies and multi-scale modeling that integrate, among others, developmental and evolutionary processes S.
The idea that evolution constitutes changing developmental relationships is central for the field of evolutionary developmental biology evo-devo. In other words, natural selection did not create variation; development creates variation. Development is the artist; natural selection is the curator Gilbert , Both have creative agency; but they are working at different levels. Waddington, and Richard B. Goldschmidt, it gained credence through more recent discoveries that explained how normal development could occur.
Chief among these discoveries was the explication of developmental pathways that connected embryonic induction with gene expression. Here, paracrine factors proteins that influence the behaviors or gene expression patterns of neighboring cells secreted by one set of cells were received by receptors on the membranes of other cells.
These receptors then activated proteins within the cytoplasm, which eventually activated or repressed proteins that entered the nucleus to regulate transcription of particular genes. The second major discovery that promoted evo-devo was the discovery of modular enhancers. The above-mentioned transcription factors would bind to specific regions of DNA, called enhancers.
Most genes have multiple enhancers. Evolution could occur by creating or deleting enhancers, thereby enabling genes to be expressed differently in different species. King and Wilson and Jacob had speculated that evolution occurred by changes in gene regulation. Activation of genes to form the distal rib, for instance, is controlled by a different enhancer than that which activates genes in the proximal rib Guenther et al.
These differences in gene expression could be categorized into four categories Arthur One of these categories involves the place of gene expression, where different populations of cells express a particular gene in different species. For instance, the gremlin gene in the duck hindlimb webbing protects these cells from cell death, enabling webbed feet Laufer et al, ; Merino et al.
A third category of change involves alterations in the magnitude of gene expression, as in the differences in Bmp4 gene expression that determine the width of finch beaks Abzhanov et al. A fourth category focuses on the alterations of the actual protein sequence of regulatory proteins, as in the changes of the Antennapedia gene in insects, which restrict insects from forming more than six limbs Galant and Carroll The third discovery was the elucidation of gene regulatory networks GRNs. A GRN is based on paracrine factors, signal transduction cascades, and transcription factors.
While ignoring post-transcriptional gene regulation, this concept attempts to explain how initial conditions RNAs and proteins within the oocyte, position of the embryo within the uterus, etc. More generally, the discovery of GRNs has enabled the integration of developmental biology with paleontology Jablonski ; Hinman et al. A fourth discovery of evolutionary developmental biology was the importance of developmental plasticity for evolution Nijhout ; Gilbert ; Pigliucci By the end of the 20th century, the roles of temperature, sunlight, diet, crowding, maternal behaviors, and predation were seen to have major roles in effecting phenotypes in plants and animals.
Thus, the environment not only selected variations, it helped produce them. Since evo-devo postulated that changes in development cause evolution, and since developmental plasticity played a role in development, then it became necessary to look at changes in plasticity as being part of evolution.
In the early years of the 21st century, developmental plasticity was seen to play roles in evolutionary change West-Eberhard ; Abouheif et al. The mechanisms by which such plasticity-first evolution was effected unmasking and selection of cryptic genetic variants, stress-related inability of molecular chaperones to allow proper folding of mutant proteins, etc.
A fifth discovery was the realization that one of the major environmental agents effecting development were symbiotic microbes McFall-Ngai ; Gilbert et al. The notion of the holobiont i. For instance, in the mouse, the normal development of the immune system and the gut capillary network depends upon specific bacteria obtained during birth. These bacteria induce the expression of particular genes in the eukaryotic cells, and the proteins made by these genes influence cell fate Hooper et al.
In other words, the bacteria can act as an embryonic cell would, regulating gene expression in neighboring cells. Here, the eukaryotic organism needs and expects these bacteria to be present for normal development. As in the other cases of developmental plasticity, the next step was to see if changes in developmental symbionts could produce changes in evolution see O'Malley It was shown that changes in symbionts could provide selectable variants for evolution Zhang et al. One of the most interesting possibilities, though, comes from the view that most, if not all, eukaryotic organisms are holobionts, and that symbionts open new evolutionary trajectories.
Symbiotic microbes, for instance, have long been known to be responsible for the plant-digesting enzymes in the stomachs of ruminants. Without cellulose-digesting bacteria, cows cannot digest grass or grain. Moreover, the microbes help create the rumen after they colonize the digestive system at birth.
Developmental symbiosis sympoiesis thus has opened evolutionary trajectories for certain mammals. This is an example of both developmental symbiosis and niche construction. Niche construction depends on developmental plasticity Laland et al. These five new or renewed aspects of developmental biology have several philosophical implications. Among others, they concern ontological questions of what developing organisms are and how they should be explained from an integrated perspective of developmental evolution.
Many ontological debates on the relation between development and evolution focus on the organism as the central unit, which both develops and evolves, in contrast to, for example, genes or populations. These ideas of life cycle integration and ubiquitous reciprocity suggest a more processual and organism-centered ontological perspective on the organism.
This view is becoming important in studies of evolution. For example, in order to understand how nervous systems evolve one need to consider that the nervous system of the developing organism has different functions than the adult nervous system and may be used to coordinate body construction as it develops M. Levin ; Fields et al. That developing systems show exaptation and competition and that evolving systems show cooperation has allowed Fields and Levin forthcoming to suggest that developmental and evolutionary processes can be integrated on a scale-free level through the language of information processing and communication.
Therefore, our discussions about evolution must take into consideration that each organism is a consortium having numerous genomes, not just one, as traditionally assumed. Mathematical modeling of the evolution of holobionts that take this diversity into consideration is just beginning Roughgarden et al. This new ontological framework states that symbiosis is the norm; it is not peripheral. A third ontological point concerns the exact nature of the link between development and evolution.
Two approaches have been put forward: One draws on the idea that the biological entity that is causally efficacious in both realms can only be found on the level of integrated collectives of symbiotic interactions.
This leads to a view of evolution that is not centered on interspecies conflict and competition between individuals Huxley ; Williams ; Dawkins A different ontological framework links development and evolution through the entity of the acting organism Nicholson , ; Walsh ; for discussion, see Pradeu ; Baedke a, b. These approaches usually are less related to symbiosis research than to studies on niche construction or maternal effects. Here the organism e. Thus, so the argument goes, it can bias and direct population dynamics.
Whether or not we consider collectives or organismic individual agents as the core entities partaking both in development and evolution, attempts to integrate the two realms have to show in each case that, in fact, it is the same unit that develops and evolves.
In other words, if we want to unify development and evolution through the unit of the biological individual being the one entity that partakes in both this unit needs to meet criteria of both physiological e. Unfortunately, both of these units do not always coincide Godfrey-Smith ; Pradeu For example, some organisms holobionts form developing but no reproductive units, as they include a multitude of lineages e.
Other possible units of selection like genes or populations are not identical with physiological individuals. Thus, a physiological individual may not necessarily be an evolutionary unit or vice versa. This brings us to a fourth ontological point: developmental plasticity, which is considered to bias or even guide evolutionary trajectories West-Eberhard ; Radersma et al.
The concept of plasticity states that development can be regulated in important ways by the environment. This rules out genetic determinism but not necessarily environmental determinism; see Waggoner and Uller In the original conception of phenotype production i. In line with this view, many embryology texts in the late s e.
Despite this history, developmental plasticity was marginalized as genetic explanations came to the fore in the midth century Sarkar ; Keller Due to the above findings on organism-environment interaction see section 3 , a different view emerged that more seriously considers the environmental-responsiveness and plasticity of the developing phenotype.
This view includes a shift from externalist to internalist or constructionist understandings of the organism-environment relationship Godfrey-Smith While the externalist view — the orthodox view in evolutionary theory — conceptualizes properties of organisms as a result of their environments i. According to these two accounts, organisms occupy an environment that covaries with them or that is largely independent of their variation. The above research in developmental evolution suggests a switch from an externalist to a constructionist perspective, in which the organism actively molds its internal states and responds to and alters its external environment see Laland et al.
In addition, in this framework also the causal role of the environment becomes more complex. It now includes the idea that the environment has active agency that can determine the phenotype. Besides these discussions about the ontology of developing and evolving organisms, other central philosophical debates on the interface between development and evolution have targeted the topic of scientific explanation. This refers to the questions of what studies of developmental evolution should explain and how they explain.
Philosophers of science have long argued for the explanatory autonomy of biological explanations. Especially, they have criticized understanding biological explanation as similar to law-based accounts of explanations in physics see Lange Especially evo-devo has been described as a paradigmatic mechanistic science, which — against the ultimate-proximate distinction — seeks to identify developmental mechanisms that can explain evolutionary change in phenotypes Gilbert ; Hall However, besides the accepted centrality of mechanistic explanation for developmental evolution, a much-debated topic concerns what exactly a developmental mechanism is and how it functions in evolutionary explanation compared to standard explanations citing natural selection.
Philosophers of biology in the so-called new mechanistic philosophy have conceptualized mechanistic explanations in biology as the construction of models of mechanisms that connect parts of systems, located on one level of organization, with behaviors of the whole system, usually located on a higher level of organization Machamer et al.
In this framework, mechanistic models relate different compositional levels of organization, like genes and phenotypes or cells and tissues. These inter-level relations exist between causal capacities of parts of a system and their organization and the capacities of a system as a whole. This conceptual framework to describe biological mechanisms and mechanistic explanation has been developed based on case studies in molecular and cell biology. However, scholars have cast doubt on whether it is also useful to describe mechanistic explanations in studies of development and developmental evolution.
With respect to development, it has been argued, first, that organization plays a different role in mechanistic developmental explanations Mc Manus In contrast to the above framework, which usually presupposes that levels of organization are simply there, and thus it does not have to clarify how levels of organization actually originate, the origin of levels and other forms of organization e.
Third, it has been argued that explanations in evo-devo using developmental mechanisms face a challenge due to the heterogeneity of these mechanisms Love When trying to integrate two types of explanations of developmental mechanisms — explanations of highly conserved molecular genetic mechanisms, like gene regulatory networks, and explanations of cellular-physical mechanisms, like cell migration — sometimes a tradeoff emerges.
Rather than allowing a more complete explanation, integrating the two mechanisms may lead to a less general explanation, since non-phylogenetically conserved cellular-physical mechanisms yield less generality in explanations. This tradeoff can introduce an explanatory bias to projects that seek to integrate development and evolution.
It could lead researchers to favors the generality of explanations, which cite highly conserved molecular genetic mechanisms and no cellular-physical mechanisms, over integrated explanations citing both kinds of mechanisms. With respect to the concept of mechanism in developmental evolution, Brigandt highlights that some mechanistic explanations in evo-devo — like those on how development biases evolution Radersma et al. Learn More Evolution Since Darwin. Sexual reproduction allows an organism to combine half of its genes with half of another individual's genes, which means new combinations of genes are produced every generation.
In addition, when eggs and sperm are produced, genetic material is shuffled and recombined in ways that produce new combinations of genes. Sexual reproduction thus increases genetic variation, which increases the raw material on which natural selection operates. Genetic variation within a species -- also known as genetic diversity -- increases a species' opportunity for change over successive generations. Learn More The Advantage of Sex.
Evolution is not a random process. The genetic variation on which natural selection acts may occur randomly, but natural selection itself is not random at all. The survival and reproductive success of an individual is directly related to the ways its inherited traits function in the context of its local environment. Whether or not an individual survives and reproduces depends on whether it has genes that produce traits that are well adapted to its environment. Learn More Life's Grand Design. Evolution and "survival of the fittest" are not the same thing.
Evolution refers to the cumulative changes in a population or species through time. Natural selection works by giving individuals who are better adapted to a given set of environmental conditions an advantage over those that are not as well adapted. Survival of the fittest usually makes one think of the biggest, strongest, or smartest individuals being the winners, but in a biological sense, evolutionary fitness refers to the ability to survive and reproduce in a particular environment.
Popular interpretations of "survival of the fittest" typically ignore the importance of both reproduction and cooperation. To survive but not pass on one's genes to the next generation is to be biologically unfit. And many organisms are the "fittest" because they cooperate with other organisms, rather than competing with them.
Learn More Adaptation and Natural Selection. In the process of natural selection, individuals in a population who are well-adapted to a particular set of environmental conditions have an advantage over those who are not so well adapted. The advantage comes in the form of survival and reproductive success.
For example, those individuals who are better able to find and use a food resource will, on average, live longer and produce more offspring than those who are less successful at finding food. Inherited traits that increase individuals' fitness are then passed to their offspring, thus giving the offspring the same advantages.
PubMed Google Scholar. Bonner JT. Evolution and development. Life Sciences Research Report Berlin: Springer; Bowler PJ. Life's splendid drama. Evolutionary biology and the reconstruction of life's ancestry — Chicago: The University of Chicago Press; Brylski P, Hall BK. Ontogeny of a macroevolutionary phenotype: the external cheek pouches of geomyoid rodents. Epithelial behaviour and threshold effects in the development of external and internal cheek pouches in rodents.
Zool Syst Evolutionsforsch. Calow P. Life cycles: an evolutionary approach to the physiology of reproduction, development and ageing. London: Wiley; Evolutionary principles. Blackie: Glasgow and London; Carroll SB. Evo—devo and an expanding evolutionary synthesis: a genetic theory of morphological evolution. Homeotic genes and the regulation and evolution of insect wing number. From DNA to diversity. Molecular genetics and the evolution of animal design.
Malden: Blackwell Science; The impact of the gut microbiota on human health: an integrative view. Modeling in EvoDevo: how to integrate development, evolution, and ecology. In: Laubichler MD, editor. Roots of theoretical biology: the Prater Vivarium centenary. Cambridge: MIT Press; Pax genes and organogenesis. Darwin CR. The origin of species by means of natural selection.
London: John Murray; Davidson EH. The regulatory genome: gene regulatory networks in development and evolution. San Diego: Academic; Gene regulatory networks and the evolution of animal body plans. Embryos and evolution. Oxford: Clarendon; Deichman U. Early 20th-century research at the interface of genetics, development, and evolution: reflections on progress and dead ends. Dev Biol. Dobzhansky Th. Genetics and the origin of species.
New York: Columbia University Press; Paleobiology Suppl. The Cambrian conundrum: early divergence and later ecological success in the early history of animals. Fusco G, Minelli A. Phenotypic plasticity in development and evolution: facts and concepts.
Gehring WJ. The homeobox: a key to the understanding of development? Master control genes in development and evolution: the homeobox story. New Haven: Yale University Press; Gilbert SF, Apel D. Ecological developmental biology: integrating epigenetics, medicine, and evolution. Sunderland: Sinauer Associates; Morphogenesis of the turtle shell: the development of a novel structure in tetrapod evolution.
Evol Dev. Gissis SB, Jablonka E. Transformations of Lamarckism: from subtle fluids to molecular biology. Principles of evolutionary medicine. Oxford: Oxford University Press; Goldschmidt R.
A preliminary report on some genetic experiments concerning evolution. Am Nat. Development and evolution. Cambridge: Cambridge University Press; Gould SJ. Ontogeny and phylogeny. Greene E. A diet-induced developmental polymorphism in a caterpillar.
Phenotypic variation in larval development and evolution: polymorphism, polyphenism, and developmental reaction norms. The origin and evolution of larval form. Haeckel E. Berlin: Georg Reimer; Hall BK. Evolutionary developmental biology. London: Chapman and Hall; Homology: the hierarchical basis of comparative biology. Dordrecht: Kluwer Academic; Evo—devo or devo—evo—does it matter? John Samuel Budgett — : in pursuit of Polypterus.
Palaeontology and evolutionary developmental biology: a science of the 19th and 21st centuries. Evolution as the control of development by ecology. Environment, evolution and development: towards a synthesis. Cambridge: MIT Press; a. Unlocking the black box between genotype and phenotype: cells and cell condensations as morphogenetic modular units. Biol Philos. Homology, homoplasy, novelty and behavior.
Dev Psychobiol. Hall BK, Kerney R. Levels of biological organization and the origin of novelty. Hall K, Olson WM eds. Keywords and concepts in evolutionary developmental biology. Conrad Hal Waddington, theoretical biology, and evo—devo.
Epigenetics: linking genotype and phenotype in development and evolution. Berkeley: University of California Press; Variation: a central concept in biology.
On synergistic interactions between evolution, development and layered learning. Huxley JS. Evolution: the modern synthesis. London: Allen and Unwin; Kosik KS. MicroRNAs tell an evo—devo story. Nat Rev Neurosci. EvoDevo and niche construction: building bridges.
Laubichler MD. The Cambridge companion to the philosophy of biology. Evolutionary developmental biology offers a significant challenge to the neo-Darwinian paradigm.
Contemporary debates in philosophy of biology. Malden: Wiley-Blackwell; Laubichler MD, Maienschein J, editors. From Embryology to evo—devo: a history of developmental evolution. Introduction to the papers of the Kowalevsky Medal winner symposium. Emerging model systems in eco—evo—devo: the environmentally responsive spadefoot toad.
Into the deep: new discoveries at the base of the green plant phylogeny. Lewis EB. A gene complex controlling segmentation in Drosophila. Lickliter R. The dynamics of development and evolution: insights from behavioral embryology. Altered timing of the extracellular-matrix-mediated epithelial—mesenchymal interaction that initiates mandibular skeletogenesis in three inbred strains of mice: development, heterochrony, and evolutionary change in morphology.
J Exp Zool. Macleod R. Embryology and empire. Darwin's laboratory. Evolutionary theory and natural history in the Pacific. Honolulu: University of Hawaii Press; Maynard Smith J. Weismann and modern biology. Oxford surveys in evolutionary biology, vol. Mayr E. The growth of biological thought. Diversity, evolution, and inheritance. The establishment of evolutionary biology as a discrete biological discipline. McCain KW. Using tricitation to dissect the citation image: Conrad Hal Waddington and the rise of evolutionary developmental biology.
0コメント