For example, it has been suggested that once lost, a complex feature cannot be regained as the probability of its reemergence is too slight.
The main underlying assumption is that a character (intron in a given position) once lost cannot be regained whereas as many parallel intron losses in different branches of the tree are allowed as needed to account for the observed pattern of states.
Each of the three data sets was subjected to MP analysis under the Dollo principle (i.e., assuming that characters can be lost independently in several evolutionary lineages but cannot be regained [ 81]) using PAUP 4.0b10.
If males are produced in these 'fixed' populations, they are in principle still capable of mating and producing sperm, but it is to be expected that females will no longer fertilize their eggs, and as a consequence, sexual reproduction cannot be regained in these populations even if the PI- Wolbachia infection is cured.
In MP, different models of evolution can be applied, for example, the irreversible Dollo model (Farris 1977), which assumes that once an ancestral character is lost during the evolution of a particular organism, it cannot be regained.
Time lost at the computer cannot be regained.
Amateur status cannot be regained for a year.
Faith cannot be regained by empty gestures, such as scrapping the record books.
"Never Any End to Paris" offers an extended meditation on the shifting self, the "deep and insurmountable gap" between youth and adulthood, and how the past cannot be regained but how this is probably a very good thing, because when the past is not elusive it is horribly embarrassing.
In contrast to closed-loop studies in discrete parts industry, in agri-food supply chains the value of the final product itself cannot be regained.
