Written for non-experts, this volume introduces the mechanisms that underlie reticulate evolution. Chapters are either accompanied with glossaries that explain new terminology or timelines that position pioneering scholars and their major discoveries in their historical contexts. The contributing authors outline the history and original context of discovery of symbiosis, symbiogenesis, lateral gene transfer, hybridization or divergence with gene flow, and infectious heredity. By applying key insights from the areas of molecular (phylo)genetics, microbiology, virology, ecology, systematics, immunology, epidemiology and computational science, (...) they demonstrate how reticulate evolution impacts successful survival, fitness and speciation. Reticulate evolution brings forth a challenge to the standard Neo-Darwinian framework, which defines life as the outcome of bifurcation and ramification patterns brought forth by the vertical mechanism of natural selection. Reticulate evolution puts forward a pattern in the tree of life that is characterized by horizontal mergings and lineage crossings induced by symbiosis, symbiogenesis, lateral gene transfer, hybridization or divergence with gene flow, and infective heredity, making the “tree of life” look more like a “web of life.” On an epistemological level, the various means by which hereditary material can be transferred horizontally challenges our classic notions of units and levels of evolution, fitness, modes of transmission, linearity, communities, and biological individuality. The case studies presented examine topics including the origin of the eukaryotic cell and its organelles through symbiogenesis; the origin of algae through primary and secondary symbiosis and dinoflagellates through tertiary symbiosis; the superorganism and holobiont as units of evolution; how endosymbiosis induces speciation in multicellular life forms; transferrable and non-transferrable plasmids and how they symbiotically interact with their host; the means by which pro- and eukaryotic organisms transfer genes laterally (bacterial transformation, transduction and conjugation as well as transposons and other mobile genetic elements); hybridization and divergence with gene flow in sexually-reproducing individuals; current (human) microbiome and viriome studies that impact our knowledge concerning the evolution of organismal health and acquired immunity; and how symbiosis and symbiogenesis can be modelled in computational evolution. (shrink)

Genesis: The Evolution of Biology presents a history of the past two centuries of biology, suitable for use in courses, but of interest more broadly to evolutionary biologists, geneticists, and biomedical scientists, as well as general readers interested in the history of science. The book covers the early evolutionary biologists-Lamarck, Cuvier, Darwin and Wallace through Mayr and the neodarwinian synthesis, in much the same way as other histories of evolution have done, bringing in also the social implications, the struggles with (...) our religious understanding, and the interweaving of genetics into evolutionary theory. What is novel about Sapp's account is a real integration of the cytological tradition, from Schwann, Boveri, and the other early cell biologists and embryologists, and the coverage of symbiosis, microbial evolutionary phylogenies, and the new understanding of the diversification of life coming from comparative analyses of complete microbial genomes. The book is a history of theories about evolution, genes and organisms from Lamarck and Darwin to the present day. This is the first book on the general history of evolutionary biology to include the history of research and theories about symbiosis in evolution, and first to include research on microbial evolution which were excluded from the classical neo-Darwinian synthesis. Bacterial evolution, and symbiosis in evolution are also excluded from virtually every book on the history of biology. (shrink)

The notion of the ‘division of physiological labour’ is today an outdated relic in the history of science. This contrasts with the fate of another notion, which was so frequently paired with the division of physiological labour, which is the concept of ‘morphological differentiation.’ This is one of the elementary modal concepts of ontogenesis. In this paper, we intend to target the problems and causes that gradually led biologists to combine these two notions during the 19th century, and to progressively (...) dissociate them, retaining only the concept of differentiation by the early 20th century. We shall adhere to the following: 1. The primitive economic concept of the division of labour is not a descriptive notion denoting a type of organisation of labour, but an etiological one: the idea of a causal relationship between this type of organization and the improvement of the whole. 2. This concept rapidly interested naturalists such as Henri Milne-Edwards, who were keen to find a rational ground for hierarchizing living forms based on anatomical complexity. 3. The validation of this notion in the realms of biology was subject to at least two conditions which were far from being fully satisfied. This did not prevent, however, the initial success of the concept of the division of physiological labour during the second half of the 19th century. 4. Finally, the gradual disqualification, within the Darwinian theoretical context, of the conception of an intrinsic hierarchical rank of organisms, led to a lack of interest in the concept of the physiological division of labour, at least in its non-Darwinian and non-ecological variant (the link between the division of labour within an organism and organic perfection). (shrink)

The notion of the ‘division of physiological labour’ is today an outdated relic in the history of science. This contrasts with the fate of another notion, which was so frequently paired with the division of physiological labour, which is the concept of ‘morphological differentiation.’ This is one of the elementary modal concepts of ontogenesis. In this paper, we intend to target the problems and causes that gradually led biologists to combine these two notions during the 19th century, and to progressively (...) dissociate them, retaining only the concept of differentiation by the early 20th century. We shall adhere to the following: 1. The primitive economic concept of the division of labour is not a descriptive notion denoting a type of organisation of labour, but an etiological one: the idea of a causal relationship between this type of organization and the improvement of the whole. 2. This concept rapidly interested naturalists such as Henri Milne-Edwards, who were keen to find a rational ground for hierarchizing living forms based on anatomical complexity. 3. The validation of this notion in the realms of biology was subject to at least two conditions which were far from being fully satisfied. This did not prevent, however, the initial success of the concept of the division of physiological labour during the second half of the 19th century. 4. Finally, the gradual disqualification, within the Darwinian theoretical context, of the conception of an intrinsic hierarchical rank of organisms, led to a lack of interest in the concept of the physiological division of labour, at least in its non-Darwinian and non-ecological variant. (shrink)