David's theory of evolution: James A. Shapiro's view 2017 (Evolution)

by David Turell @, Tuesday, January 07, 2020, 20:31 (292 days ago) @ David Turell

His most recent review article is from 2017 British Royal Society program:


"Abstract: Many of the most important evolutionary variations that generated phenotypic adaptations and originated novel taxa resulted from complex cellular activities affecting genome content and expression. These activities included (i) the symbiogenetic cell merger that produced the mitochondrion-bearing ancestor of all extant eukaryotes, (ii) symbiogenetic cell mergers that produced chloroplast-bearing ancestors of photosynthetic eukaryotes, and (iii) interspecific hybridizations and genome doublings that generated new species and adaptive radiations of higher plants and animals. Adaptive variations also involved horizontal DNA transfers and natural genetic engineering by mobile DNA elements to rewire regulatory networks, such as those essential to viviparous reproduction in mammals. In the most highly evolved multicellular organisms, biological complexity scales with “non-coding” DNA content rather than with protein-coding capacity in the genome. Coincidentally, “noncoding” RNAs rich in repetitive mobile DNA sequences function as key regulators of complex adaptive phenotypes, such as stem cell pluripotency. The intersections of cell fusion activities, horizontal DNA transfers and natural genetic engineering of ReadWrite genomes provide a rich molecular and biological foundation for understanding how ecological disruptions can stimulate productive, often abrupt, evolutionary transformations.


"The preceding discussion illustrates how generic biological activities have regularly played decisive roles in major episodes of evolutionary innovation: • Horizontal DNA transfers in the origination of mesophilic archaeal taxa; • Recurring symbiogenetic cell fusions in the origination of the ancestral eukaryotic cell and the major clades of photosynthetic eukaryotes; • Interspecific hybridizations and changes in genome ploidy in speciation and adaptive radiations in yeast, plants and animals; • Amplification and relocalization of mobile DNA elements in formatting mammalian genomes for replication, viviparous reproduction, and lncRNA regulation of nervous and immune system functions. These examples show us that core biological capacities for self-modification in response to ecological challenge have been integral to the history of life on earth. That conclusion should not surprise us since extant organisms are descendants of multiple evolutionary episodes. Considering potential interactions between dynamic ecological conditions and the biological engines of cell and genome variation raises important questions about control and specificity in evolutionary innovation. The years to come likely hold surprising lessons about how cell fusions, genome doublings, and natural genetic engineering may operate non-randomly to enhance the probabilities of evolutionary success."

Comment: Worth reading the whole article. Note the lack of the exuberant descriptions of how cognoscent individual cells are. A true scientific paper will not make those claims as in his book, or as in Margulis comment about his book. Shapiro is reasonably circumspect. I will repeat: his book is a fabulous contribution as to how the genome has worked in producing evolution, without providing any answer as to how speciation occurs.

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