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Homology, Genes, and Evolutionary Innovation
Homology--a similar trait shared by different species and derived from common ancestry, such as a seal's fin and a bird's wing--is one of the most fundamental yet challenging concepts in evolutionary biology. This groundbreaking book provides the first mechanistically based theory of what homology is and how it arises in evolution.
Gunter Wagner, one of the preeminent researchers in the field, argues that homology, or character identity, can be explained through the historical continuity of character identity networks--that is, the gene regulatory networks that enable differential gene expression. He shows how character identity is independent of the form and function of the character itself because the same network can activate different effector genes and thus control the development of different shapes, sizes, and qualities of the character. Demonstrating how this theoretical model can provide a foundation for understanding the evolutionary origin of novel characters, Wagner applies it to the origin and evolution of specific systems, such as cell types; skin, hair, and feathers; limbs and digits; and flowers.
The first major synthesis of homology to be published in decades, "Homology, Genes, and Evolutionary Innovation" reveals how a mechanistically based theory can serve as a unifying concept for any branch of science concerned with the structure and development of organisms, and how it can help explain major transitions in evolution and broad patterns of biological diversity."
Gunter Wagner, one of the preeminent researchers in the field, argues that homology, or character identity, can be explained through the historical continuity of character identity networks--that is, the gene regulatory networks that enable differential gene expression. He shows how character identity is independent of the form and function of the character itself because the same network can activate different effector genes and thus control the development of different shapes, sizes, and qualities of the character. Demonstrating how this theoretical model can provide a foundation for understanding the evolutionary origin of novel characters, Wagner applies it to the origin and evolution of specific systems, such as cell types; skin, hair, and feathers; limbs and digits; and flowers.
The first major synthesis of homology to be published in decades, "Homology, Genes, and Evolutionary Innovation" reveals how a mechanistically based theory can serve as a unifying concept for any branch of science concerned with the structure and development of organisms, and how it can help explain major transitions in evolution and broad patterns of biological diversity."
496 pages, Hardcover
First published January 1, 2014
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Displaying 1 - 3 of 3 reviews
February 17, 2021
Homology is considered a clearcut and simple concept in evolutionary biology, but it isn't! Gunter Wagner addresses a number of "deep" questions that make the concept much more interesting than the simplified treatments in textbooks. Wagner argues that two morphologies are homologous if they share the same character identity network, that is, a similar genetic system that regulates their development. This argument is illustrated using a great variety of examples, varying from stem cell lineages to limb and digit development. The depth at which these examples are discussed is impressive. But most of all I like Wagners plea for a "structural" approach to evolutionary biology, that is, an approach which considers organisms not as abstract functional units with a gene frequency but as entities that develop shape and form. I couldn't agree more. Still the book is heavy stuff due to Wagner's tendency to stick to German "Gründlichkeit".
October 6, 2018
For anchoring character identity to gene regulation network activity, the avian and skink digit identity problem has so far been its most productive test case. Character identity reflects a gene regulatory state rather than a positional or descriptive fact.
In this book, cell types are held up as an example of how positive feedback among regulatory genes underlies distinct identities. The idea is that each cell identity is caused by a core gene regulatory network. One of three challenges based on recent research is that there is increasing evidence that the gene regulator network state of a cell is governed not by one core network, but by a mosaic of densely interconnected network modules each of which, in isolation, might look like a core network. One example of this principle has been found in the hematopoietic lineage in gene regulatory network modules, each of which is relatively autonomous in its expression and activation.
If this principle holds up to more experimental scrutiny, then the notion of cell identity as a unitary state will have to be revised to allow for a mosaic of character identities. It might also allow for the evolution of novel cell identities by evolutionary recombinations of gene regulatory network modules for generating new combinations of network states. In this case, the unit of historical continuity will shift from the cell to the gene regulatory network module level.
In this book, cell types are held up as an example of how positive feedback among regulatory genes underlies distinct identities. The idea is that each cell identity is caused by a core gene regulatory network. One of three challenges based on recent research is that there is increasing evidence that the gene regulator network state of a cell is governed not by one core network, but by a mosaic of densely interconnected network modules each of which, in isolation, might look like a core network. One example of this principle has been found in the hematopoietic lineage in gene regulatory network modules, each of which is relatively autonomous in its expression and activation.
If this principle holds up to more experimental scrutiny, then the notion of cell identity as a unitary state will have to be revised to allow for a mosaic of character identities. It might also allow for the evolution of novel cell identities by evolutionary recombinations of gene regulatory network modules for generating new combinations of network states. In this case, the unit of historical continuity will shift from the cell to the gene regulatory network module level.
July 26, 2020
Don’t let the timeline of my reading fool you, this is an excellent book.
I’m a comparative anatomist, but don’t work within development as much as I’d like, so this was perfect for my need to enhance my understanding of the conceptual role of development in homology.
(Personal note: I started a relationship around the time of reading this and just never made time for reading. It won’t take you this long, trust me!)
I’m a comparative anatomist, but don’t work within development as much as I’d like, so this was perfect for my need to enhance my understanding of the conceptual role of development in homology.
(Personal note: I started a relationship around the time of reading this and just never made time for reading. It won’t take you this long, trust me!)
Displaying 1 - 3 of 3 reviews