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NO SPECIES BARRIER. “They conclude that inter-specific genetic exchange was a major evolutionary driver and that one species ( S. mitis ) provided the bulk of genetic variation for another species ( S. pneumoniae ). This is not an atypical finding. In prokaryotes, the bulk of new gene families arise via inter-species horizontal gene transfer, not intra-species gene duplication.” https://lnkd.in/ewnQ9Vg View in LinkedIn

VERTICAL VERUS HORIZONTAL WORLDS. “From both a mechanical and a theoretical perspective, the way genetic material is transmitted through organisms over time is fundamentally different in prokaryotes. This leads prokaryotic biologists to use the word “species” in a manner that is decidedly at variance with the concept as applied to multi-cellular eukaryotes.” https://lnkd.in/ewnQ9Vg View in LinkedIn

DISRUPTIVE CONCEPT. “The occurrence of large-scale horizontal gene transfer certainly has the potential to disrupt the notion of lineages, shared evolutionary fate, or shared evolutionary history, three of the key constraints on species concepts useful for biodiversity studies.” https://standardsingenomics.biomedcentral.com/articles/10.1186/s40793-016-0180-8 View in LinkedIn

HORIZONTAL WORLD. “However, none of the species concepts as applied to prokaryotes satisfy any of those conditions. Paraphrasing Hey, the problems involve both the theoretical understanding of how prokaryotes exist in nature and the operational methods for identifying prokaryotic species.” https://standardsingenomics.biomedcentral.com/articles/10.1186/s40793-016-0180-8 View in LinkedIn

CLASSICAL INDIVIDUALISM. “Given the centrality of “the individual” to multi-cellular eukaryotes thinking, it is not surprising that much of classical biology is dedicated to studying the attributes and behavior of aggregations of somatic cells, i.e., individual organisms.” https://standardsingenomics.biomedcentral.com/articles/10.1186/s40793-016-0180-8 View in LinkedIn

VERTICAL WORLD. “Thus, all of the lineage-based species concepts applied to multi-cellular eukaryotes satisfy all of the biodiversity constraints noted above, viz., they are all completely anchored in the idea of shared evolutionary history and fate and they all, in consequence, deliver species groups whose members exhibit great similarity of phenotype and ecological role.” https://standardsingenomics.biomedcentral.com/articles/10.1186/s40793-016-0180-8 View in LinkedIn

TRADITIONAL SYNTHESIS. “To do this, all of the cells must cooperate with each other in a highly controlled and regulated manner, in turn requiring an extremely stable, shared and identical (nearly) genome. Ultimately, in multi-cellular eukaryotes all somatic cells live or die together as a single individual entity. In the modern synthesis, the differential survival of somatic-cell individuals and their genetically identical germ-line payloads is the driving mechanism of evolution.” https://lnkd.in/ewnQ9Vg View in LinkedIn

VERTICAL INHERITANCE. “Meaningful transfer of genetic information occurs—and only occurs—in a linear pattern from parent to progeny. This, again, is an assumption that only applies to multi-cellular eukaryotes.” https://standardsingenomics.biomedcentral.com/articles/10.1186/s40793-016-0180-8 View in LinkedIn

TRADITIONAL VIEW: “The cells of these individuals undergo differentiation into germ-line cells (ultimately gametes) and somatic cells—a “body” of tissues and organs to protect and nurture the germ line, at least until reproduction.” https://standardsingenomics.biomedcentral.com/articles/10.1186/s40793-016-0180-8 View in LinkedIn

CLASSICAL SPECIES CONCEPT. “In classical biology, individuals are seen to co-exist in local groups called populations and the set of all populations containing members capable of interbreeding is defined as a species by Mayr’s biological species concept (BSC).” https://lnkd.in/ewnQ9Vg View in LinkedIn