The Origin of Animal Body Plans: Evolutionary Developmental Biology Research Book - Perfect for Biology Students, Researchers, and Science Enthusiasts

Let's see, my take on the book in a nutshell: the conditions under which evolution operated during the Cambrian/Vendian times were different from the conditions following that time in two main ways, and these differences can potentially account for the origin of the many animal body plans during those early periods and the lack of new ones since.First, ~550 million years ago most animals were very much simpler (fewer cells, for example) than they are today, so changes to their developmental programs would have been better tolerated. The more complex any system is (the more parts it has, the more coordinated and well-matched those parts must be, etc.), the more rigidly constrained and less amenable to a given magnitude of change it is. So the simpler developmental processes (simpler adult-form end product, fewer interactions between developmental genes, etc.) of early animals would have allowed for a 'large-scale' change to be incorporated into that animal's ontogeny, though if a change of the same magnitude were to occur today, it would be too disruptive to the complex developmental program and would be eliminated (note that 'large-scale change' refers to the adult form: the actual change that caused that altered end result could be a typical small scale mutation, in an early developmental stage). The author is not proposing Goldschmidt's "hopeful monsters" that occur due to 'macromutations', but rather an intermediate position between that and the "only micromutations" view of gradualistic neo-Darwinism. And, as just mentioned, mutations in developmental processes (even ones that resulted in 'macromutations' in the adult form) would have been more tolerated in the simpler animals that existed ~550 mya than they would be in today's.Second, ~550 million years ago animal diversity was extremely more limited than it is today, so there was a huge number of open niches: a plentitude the likes of which has never again existed on our planet. An organism that happened to find itself in one of the multitude of open niches (by means of a "semi-macro" mutation, the product of a change in a developmental gene) would have faced little if any competition. The reduced external competition would potentially allow the morpholigical variation(s), that would otherwise likely have been eliminated, to persist. (The sudden change could leave the organism with a lower level of internal coordination: over time, internal cooadaptation could evolve to 'catch up' with the change in morphology: these internal adjustments would leave no trace in the fossil record).Combining these two ideas produces a reasonable explanation of the 'explosion' in new body plans in Vendian/Cambrian times.Of course there's much more to the book than my above "nutshell" presentation. The Evo-Devo perspective presented in the book allowed me to view evolution in a new way: it gave me a better understanding of the "creative" side of evolution than I had before when viewing things solely from a gradualistic, neo-Darwinian frame of reference.PS: The book is "aged" (1997) but is not outdated.