8/5/2023 0 Comments Zhang jing shu![]() ![]() This network approach, based on mitochondrial and Y chromosomal data, allowed us to reconstruct the prehistoric population movements which colonized the planet ( 4, 5 ). This motivated the development, in the early 1990s, of phylogenetic network methods which are capable of enabling the visualization of a multitude of optimal trees ( 2, 3 ). It soon turned out, however, that the tree-building method did not facilitate an unambiguous interpretation of the data. The search for human origins seemed to take a step forward with the publication of the global human mitochondrial DNA tree ( 1 ). ![]() The network faithfully traces routes of infections for documented coronavirus disease 2019 (COVID-19) cases, indicating that phylogenetic networks can likewise be successfully used to help trace undocumented COVID-19 infection sources, which can then be quarantined to prevent recurrent spread of the disease worldwide. In contrast, the B type is the most common type in East Asia, and its ancestral genome appears not to have spread outside East Asia without first mutating into derived B types, pointing to founder effects or immunological or environmental resistance against this type outside Asia. ![]() The A and C types are found in significant proportions outside East Asia, that is, in Europeans and Americans. In a phylogenetic network analysis of 160 complete human severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) genomes, we find three central variants distinguished by amino acid changes, which we have named A, B, and C, with A being the ancestral type according to the bat outgroup coronavirus. ![]()
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