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Evolution as Frozen Music
Abstract
Developmental Plasticity and Evolution. by Mary Jane West-Eberhard. Oxford University Press, New York, 2003. 814 pp. 49.95,
£31.99. ISBN 0-19-512235-6.
Discussing a wide range of ideas and empirical studies that support them, West-Eberhard focuses on showing what recent findings
in development, physiology, and behavior suggest about the origins of evolutionary novelties.
... BCE, Marcus Vitruvius Pollio suggested that architects should be educated in all the arts and have a vast knowledge of history, music and philosophy [38]. In the eighteenth c., the German thinker Johann Wolfgang von Goethe described architecture as frozen music [26]. More recently, in the twentieth c., Iannis Xenakis studied the similar structuring principles between music and architecture, creating his own models of musical composition based on mathematical principles and geometric constructions [9]. ...
Every architectural building design is a combination of various geometrical forms. These forms are generated from the geometrical shapes such as circles, squares, and triangles which undergoes transformations to form substructures. These substructures are then organized to form an architectural design. Similarly, in music a substructure may involve one or more notes in the chosen musical scale, which undergoes transformations to form substructures. These musical substructures are then organized in appropriate musical measures to compose music. A methodology has been employed to transformed architectural substructures to form respective musical substructures and vice-versa. The methodology includes deciphering architectural building design from music and vice-versa using a grid-based logic. This grid-based logic involves the visual parameters: length, height and width in architecture and the aural parameters: time, frequency and loudness in music; for X, Y, Z axes in the respective visual and musical grid. This method has been evaluated using the transformations involved in both architecture and music. Thus, the output of the above process enhances the existing libraries in both building design and music through the transformation of substructures.
Since seedling emergence is important to survival and establishment, environment factors are often responsible for seedling emergence. Hypocotyl elongation plays a major role for emergence, thus growth of it in response to light change and burial depth becomes a strategy that may ensure seedling development. Seeds of Xanthium strumarium, Abutilon theophrasti and Pharbitis purpurea were sown in pots at 2, 4 and 6 cm depths and grown under shades giving 30, 60 and 100% light transmission treatments. In the treatments, the percent emergence was significantly affected by burial depth but not by light transmission, it was highest at 2 cm burial depth, but decreased with increasing burial depth. There was a significant positive correlation between the number of days to first emergence and burial depth. Light and burial depth negatively influenced the extension of hypocotyl aboveground and seedling height, maximum elongation growth occurred in the 30% light transmission treatment and at 2 cm depth, and decreased with increasing burial depth and decreasing light transmission treatment, but the length and weight of hypocotyl belowground and root were only significantly affected by burial depth, not by light transmission. In each light transmission treatment, with increasing burial depth, both aboveground mass and belowground mass decreased, while belowground mass of hypocotyl increased. In each burial depth, with decreasing light transmission, both aboveground mass and belowground mass decreased, while belowground mass of hypocotyl decreased.
Ecological Developmental Biology Integrating Epigenetics, Medicine, and Evolution by Scott F. Gilbert and David Epel Sinauer Associates, Sunderland, MA, 2009. 496 pp. $49.95. ISBN 9780878932993.
Gilbert and Epel focus on embryonic and larval development of metazoans to explore where "embryology meets the real world."
The concept of genetic accommodation remains controversial, in part because it remains unclear whether evolution by genetic accommodation forces a revolution, or merely a shift in emphasis, in our understanding of how evolution produces adaptive new traits. Here I outline a perspective that largely favors the latter view. I argue that evolution by genetic accommodation can easily be integrated into traditional evolutionary concepts. At the same time, evolution by genetic accommodation invites novel empirical and theoretical approaches that may allow biologists to push the boundaries of our current understanding of the process of evolution and to solve some long-standing controversies. Specifically, I discuss the role of developmental mechanisms as natural, and likely ubiquitous, capacitors of cryptic genetic variation, and the role of environmental perturbations as mechanisms by which such variation can become visible to selection on an individual to population-wide scale. I argue that in combination, developmental capacitance and large-scale environmental perturbations have the potential to facilitate rapid evolution including the origin of novel adaptive features while circumventing otherwise powerful genetic and population-biological constraints on adaptive evolution. I end by highlighting several promising avenues for future empirical research to explore the mechanisms and significance of evolution by genetic accommodation.
An evolutionary change in development was studied in two closely related ascidian species, one exhibiting a conventional tadpole larva and the other a modified tailless larva. Interspecific hybridization restores chordate features to the tailless larva. The zinc finger gene Manx is expressed in cells that generate chordate features in the tailed species but is down-regulated in the tailless species. Manx expression is restored in hybrid embryos. Antisense oligodeoxynucleotide treatment inhibited Manx expression and chordate features in hybrid embryos, which suggests that Manx is required for development of the chordate larval phenotype in ascidians.
Whole-genome sequence assemblies are now available for seven different animals, including nematode worms, mice and humans. Comparative genome analyses reveal a surprising constancy in genetic content: vertebrate genomes have only about twice the number of genes that invertebrate genomes have, and the increase is primarily due to the duplication of existing genes rather than the invention of new ones. How, then, has evolutionary diversity arisen? Emerging evidence suggests that organismal complexity arises from progressively more elaborate regulation of gene expression.
Consequently, a detailed knowledge of these early fossil forms must be of fundamental importance for questions concerning the
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