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ANTIGENIC SHIFT. "The reassortment of complete units of genetic material results in the formation of ‘reassortants’ or ‘mosaic’ viruses. At times, ‘genetic reassortment’ affects the exchange of genome segments encoding the viral surface proteins hemagglutinin and neuraminidase. Thereby, the virus achieves a new antigenic pattern." https://lnkd.in/d8xM5QF View in LinkedIn

APPEARANCE OF HOMOLOGY. "As was recently demonstrated for the regulation of the floral homeotic gene AGAMOUS by orthologues of LEAFY in different flowering plants, variation in TF binding sites can simultaneously form the basis for conserved as well as divergent regulatory interactions, leading to novel phenotypes: observed changes in expression patterns that appear to be similar may not be caused by homologous genetic processes." (TF = transcription factors). https://lnkd.in/dD4GcAS View in LinkedIn

GENETIC SHUFFLING. "Besides mutations, viruses with segmented genomes change genetically through ‘genetic reassortment’. The latter term denotes the exchange of one or more genome segments between two related viruses which infect a host cell at the same time. During such a double infection the construction plans of both viruses become replicated in one host cell." https://lnkd.in/d8xM5QF View in LinkedIn

SUPER FAST EVOLUTION. "Three characteristics contribute to the rapid evolution of these viruses: large populations, short generation times and high mutation rates. Every mutation, which enables its carrier to evade the host’s immune system, will be (positively) selected, passed on to the next generation and distributed more widely. Influenza viruses evolve 1 million times faster than mammals. Five years of virus evolution roughly correspond to the time span, which separates humans and chimpanzees from their last common ancestor." https://lnkd.in/d8xM5QF View in LinkedIn

KEY FACTORS OF VIRUSES. "Most pathogens have large population sizes and short generation times. This is particularly true for viruses. The complete replication-cycle of a virus within a host cell often takes only a few hours and results in many thousands new viruses. Because the viral RNA-polymerase does not possess a proof-reading-function, faulty nucleotides are integrated during replication with a likelihood of 10(-3) to 10(-4), which results in high mutation rates. In fact, the error rate of the viral RNA-polymerase is 1000 times higher than the error rate of the human DNA- polymerase." https://lnkd.in/d8xM5QF View in LinkedIn

SO ENDS this consideration of the genetic drivers of flower shape. This was a difficult topic but hopefully worth it. Animals and plants differ significantly in their construction and underlying genetics, and the rampant gene duplication in plants appears to give a vast range of options for natural selection to act upon and allow considerable phenotypic diversity to emerge. View in LinkedIn

SILENT DUPLICATION EFFECTS. "Mutations in the coding regions of genes involved in a regulatory network can cause changes in protein–protein interactions, but these interactions could occur in a restricted, tissue-specific manner and impact a subset of developmental functions. The presence of duplicated genes means that mutations and subsequent drift or natural selection affecting genes or their targets can occur without necessarily changing the essential function of an existing GRN." (GRN = gene regulatory networks). https://lnkd.in/dD4GcAS View in LinkedIn

NETWORK BUFFERING. "The same benefits of modularity that were evoked to hypothesize why cis-regulatory changes would be less pleiotropic than functional changes apply as well to the modularity of GRNs as effectors of gene regulation and expression, with the GRN acting as a buffer against any widespread negative effects of a coding mutation in a developmental gene." (GRN = gene regulatory networks). https://lnkd.in/dD4GcAS View in LinkedIn

SPARED BY REDUNDANCY. "Because of modularity in plant development and redundancy in GRNs underlying developmental processes, however, a change in a protein sequence may not have the massive negative pleotropic effects that were once considered to eliminate such changes from playing a role in developmental evolution." (GRN = gene regulatory networks). https://lnkd.in/dD4GcAS View in LinkedIn

REGULATORY MUTATIONS. "Unlike with functional mutations, regulatory mutations would not impact the physical interactions and function of the encoded protein, enabling essential metabolic or cellular functions to proceed." https://lnkd.in/dD4GcAS View in LinkedIn