DNA Barcoding and Species

[Strange]

In another thread (not worth reading) there was a link to this paper: https://phe.rockefeller.edu/news/wp-content/uploads/2018/05/Stoeckle-Thaler-Final-reduced.pdf

One of the interesting (fascinating, even) results of their study is that species are well defined by the mitochondrial DNA "barcode"; in other words the individuals within a species have one barcode, those in another have a different one and there is nothing in between. As one of the authors put it: "if individuals are stars, then species are galaxies".

Although I can't see it in the paper (I have only skimmed it and much of it is over my head - without giving it more time than I have available!) it is claimed in interviews with the authors that this suggests that 90% of species arose in the last 100,000 years. For example: https://phys.org/news/2018-05-gene-survey-reveals-facets-evolution.html

I haven't found any serious discussions of the conclusions (hence this thread).

I'm not sure this is justified. Without some sort of mass extinction or bottleneck event, why would large numbers of new species arise? One of the authors suggests:

Quote

“The simplest interpretation is that life is always evolving,” said Stoeckle. “It is more likely that — at all times in evolution — the animals alive at that point arose relatively recently.” In this view, a species only lasts a certain amount of time before it either evolves into something new or goes extinct.

https://www.news.com.au/technology/science/evolution/why-did-the-overwhelming-majority-of-species-in-existence-today-emerge-at-about-the-same-time/news-story/eb87b10a8c6f8bd3cfac0a50bd7bd7f0

But that doesn't seem to be consistent with the close grouping of DNA barcodes.

An alternative might be that the single sequence they look at is highly conserved. After all, faults in the mitochondria can be highly destructive and the sequence they use may be critical to its operation (I have no idea if this is the case or not). And, presumably, those coming up with the idea of barcoding species would have chosen a stable sequence to use.

Any other thoughts?

 

 

[Endy0816]

18 hours ago, Strange said:

In another thread (not worth reading) there was a link to this paper: https://phe.rockefeller.edu/news/wp-content/uploads/2018/05/Stoeckle-Thaler-Final-reduced.pdf

One of the interesting (fascinating, even) results of their study is that species are well defined by the mitochondrial DNA "barcode"; in other words the individuals within a species have one barcode, those in another have a different one and there is nothing in between. As one of the authors put it: "if individuals are stars, then species are galaxies".

Although I can't see it in the paper (I have only skimmed it and much of it is over my head - without giving it more time than I have available!) it is claimed in interviews with the authors that this suggests that 90% of species arose in the last 100,000 years. For example: https://phys.org/news/2018-05-gene-survey-reveals-facets-evolution.html

I haven't found any serious discussions of the conclusions (hence this thread).

I'm not sure this is justified. Without some sort of mass extinction or bottleneck event, why would large numbers of new species arise? One of the authors suggests:

https://www.news.com.au/technology/science/evolution/why-did-the-overwhelming-majority-of-species-in-existence-today-emerge-at-about-the-same-time/news-story/eb87b10a8c6f8bd3cfac0a50bd7bd7f0

But that doesn't seem to be consistent with the close grouping of DNA barcodes.

An alternative might be that the single sequence they look at is highly conserved. After all, faults in the mitochondria can be highly destructive and the sequence they use may be critical to its operation (I have no idea if this is the case or not). And, presumably, those coming up with the idea of barcoding species would have chosen a stable sequence to use.

Any other thoughts?

Wiki has a good article on it.

https://en.m.wikipedia.org/wiki/DNA_barcoding

 

Does mention possibility for errors , two different species ending up with the same 'barcode'. Also talks about how the mutation rate of mitochondria is higher but effective population of carriers(females) is less than the species total.

Didn't see anything there on how recent splits are.

It is definitely interesting.

[Strange]

3 hours ago, Endy0816 said:

Wiki has a good article on it.

https://en.m.wikipedia.org/wiki/DNA_barcoding

 

Does mention possibility for errors , two different species ending up with the same 'barcode'. Also talks about how the mutation rate of mitochondria is higher but effective population of carriers(females) is less than the species total.

Didn't see anything there on how recent splits are.

It is definitely interesting.

Thanks. I'll take a look at that. It might fill in some of the gaps ...