I am reading through Recombinant DNA; Genes and Genomes - A Short Course - Third Edition by James D. Watson, et. al. and I came across this paragraph in the discussion about discrete factors of inheritance in Mendelian genetics:
The character shown by a plant depends on the pair of factors it receives from its parents. If both factors it receives are the same, that is, two dominant (yellow seed) or two recessive (green seed), then the plant exhibits those traits - yellow seeds for the former and green seeds for the latter. If one factor is dominant and the other recessive, then the dominant character is expressed; in this case, a plant with a factor for yellow seed and one for green seed will show the dominant trait, yellow seed. But the factor for green seed persists, even if the plant is yellow, and can reappear unchanged in later generations. This was a signal advance. In the 19th century it was believed that the traits of parents were blended in their offspring and, once mixed, the contributing traits could not be recovered. At the time, this was a severe problem for Charles Darwin's theory of evolution through natural selection. His critics pointed to that any favorable variation arising in an individual would have no long-term effect, because it would immediately be lost by blending.
Note: Added emphasis is mine.
I have done both Google and Google Scholar searches for
- Signal Advance
- Signal Advance Biology
- Signal Advance Genetics
- Signal Advance Science
and I have not had much success finding a definition for the use in this context.
One article, Plant biology: Signal advance for abscisic acid was one of the only relevant references I could find that used the words in combination, however they were only used in the title.
I am not sure of the context that it is being used in Recombinant DNA or in the plant biology article.
Are they saying that the signal advance marked a change in thinking on the subject, the way we would use the terms paradigm shift or quantum leap?
Or are they instead using the term in the sense of the recessive gene being maintained in the genome and was able to be expressed in future generations?
I have not come across the use of the term signal advance before, and it is difficult to work out from the context as the first half of the paragraph speaks about the genetics and then the second paragraph discusses how it provided evidence to change the hypothesis of the day.
There is a similar problem with the plant biology news and views as it talks about six new papers on a topic that had been elusive, but as it happens to be about a signaling pathway; I am left wondering the context here as well.
If anyone has come across this before and can help to clarify it for me, I would appreciate it. Thank you.