Unlike transposable elements, which spread by copying and insertion into preexisting sequences, both USSs and DUSs arise and spread by a combination of mutation and homologous recombination (Redfield et al. 2006; Treangen et al. 2008).
In the real world, new traits evolve as mutations arise and spread gradually through entire populations.
Since the generation time of individual organisms is likely to be much shorter than that of groups, the probability that a selfish mutant will arise and spread is very high, according to this line of argument.
With technology these days, the report of any complaints or conflicts that arise can spread like a wildfire, so take the preventative measures to protect your business and keep a solid reputation.
Three factors may explain the rate at which immune escape variants arise and spread.
In a polio-free IPV-user country, poliomyelitis can arise and spread to contacts who are not properly vaccinated.
In parthenogenetic populations, new genetic variants could arise and spread by mutation in the germline, and with the occurrence of meiosis, new combinations could arise by recombination.
Horizontal gene transfer also increases opportunities for advantageous gene combinations to arise and spread in the population (Silva et al. 2011).
This makes the study of how variation can arise and spread (e.g., de novo mutations vs. standing genetic variation) and the underlying evolutionary forces (e.g., drift vs. selection) very difficult to pursue above the level of species.
In addition, it is essential to describe the dynamics of how the mutations that cause phenotypic variation arise and spread in populations and ultimately contribute to speciation and macroevolutionary change.
