6th Sep, 2016
Università di Pisa
Question
Asked 31st Aug, 2016
What is the Tajima's D and Fu and Li's D and F statistics biological significance?
I am analyzing a set of 203 intra-population sequences of a gene using DnaSP and getting the Tajima's D and Fu and Li's D and F statistic values in negative with P values being significant P< 0.02. Can any one help me in interpreting the biological significance of this?
Most recent answer
Results from these statistics should be interpreted with great care. Depending on the genetic marker(s) employed, the target species, the sampling design, etc., interpretations may be not univocal. I would recommend you to study a little bit the theoratical bases of each statistics and read good articles with their applications, instead to search for shortcuts in RG. Good luck.
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Popular answers (1)
Results from these statistics should be interpreted with great care. Depending on the genetic marker(s) employed, the target species, the sampling design, etc., interpretations may be not univocal. I would recommend you to study a little bit the theoratical bases of each statistics and read good articles with their applications, instead to search for shortcuts in RG. Good luck.
4 Recommendations
All Answers (4)
Negative Tajima's D signifies an excess of low frequency polymorphisms.
Arur is right.
It will tend to be negative under selective sweeps (and population growth) and positive under balancing selection (or population structure with sampling from many populations)
Fu &Li D 's negative value indicates an excess of singletons
Pls refer to Pg 54 of this DNASP doc : http://www.ub.edu/dnasp/DnaSPHelp.pdf
Significant departure of these tests has been explained mainly to be due to an excess of new mutations as results of evolutionary forces, such as selective sweeps or population growth. Processes that produce an excess of old mutations also render significant but positive departures.
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Hello Amit,
There was a similar question with several answers that may be helpful.
Also below is a link from University of Connecticut that has a good explanation of these statistics.
But the simple answer as everyone has mentioned is that there is a population expansion.
Best Regards
3 Recommendations
Results from these statistics should be interpreted with great care. Depending on the genetic marker(s) employed, the target species, the sampling design, etc., interpretations may be not univocal. I would recommend you to study a little bit the theoratical bases of each statistics and read good articles with their applications, instead to search for shortcuts in RG. Good luck.
4 Recommendations
Similar questions and discussions
What is the relevant time scale to interpret Tajima's D?
Tajima's D is a population genetic test statistic reflecting the difference between the mean number of pairwise differences and the number of segregating sites (https://en.wikipedia.org/wiki/Tajima%27s_D).
The values of Tajima's D are interpreted as follows:
Tajima's D=0: Population evolving as per mutation-drift equilibrium.
Tajima's D<0: Recent selective sweep or population expansion after a recent bottleneck.
Tajima's D>0: Balancing selection or sudden population contraction.
I would like to ask about the relevant time scale to interpret Tajima's D. Perhaps someone could suggest publications mentioning time or number of generations when interpreting Tajima's D?
Tanks!
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