14-03-2026 13:51
Thierry Blondelle
Hi everybody Under Quercus ilex, i hesitate to na
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Bonjour, Je cherche des indices pour cette réc
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Åge OterhalsDear forum,I found this small discomycete on a ver
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Bruno Coué
Bonjour, je serais heureux d'avoir votre avis sur
DNA match
Malcolm Greaves,
27-01-2026 11:43
Is anyone with experience of DNA testing able to tell me if a 97% match to a know species is enough to justify giving it that name or is it likely to be a related but different species?Thanks
Mal
Nicolas VAN VOOREN,
27-01-2026 11:52
Re : DNA match
Well, you cannot answer by yes or no to such a question. It depends of what type of sequence (locus) you compare, length of these sequences, quality of your sequence, etc.
In the best case, with 97% you can hypothesize this is a different 'species', but to be sure, you must generate a phylogeny and also evaluate the morphological differences.
In the best case, with 97% you can hypothesize this is a different 'species', but to be sure, you must generate a phylogeny and also evaluate the morphological differences.
Hans-Otto Baral,
27-01-2026 12:02
Re : DNA match
Assuming that you have an ITS sequence, the idea of 97% similarity resp. 3% distance is antiquated. In some groups of fungi this works, in others you need to accept lower distances, such as 1.5-2%, and in some there is no difference at all in the ITS between species and you must use other regions. To evaluate an ITS distance you must search for ATCATTA and TGACCT in your sequence and only test the part between them. When you got the distance in GenBank Blast you must look how many gaps are among the differences, because these count less than nucleotide differences. What kind of fungus do you have?
Malcolm Greaves,
27-01-2026 12:59
Re : DNA match
It was a Geoglossum which was a perfect fit microscopically for G pseudoumbratile. The DNA came back with a 97.1% match to umbratile.
The test was accompanied with the note
Your sample has been processed and analysed using DNA techniques. For this analysis,
the commonly used regions for DNA Barcodes of fungi, Domain 1 and Domain 2 of the large
ribosomal subunit (D1/D2 regions of LSU rDNA) have been sequenced. Sequencing results
have been locally aligned against the NCBI database
Unfortunately I don’t have much experience of this form of analysis.
Mal
The test was accompanied with the note
Your sample has been processed and analysed using DNA techniques. For this analysis,
the commonly used regions for DNA Barcodes of fungi, Domain 1 and Domain 2 of the large
ribosomal subunit (D1/D2 regions of LSU rDNA) have been sequenced. Sequencing results
have been locally aligned against the NCBI database
Unfortunately I don’t have much experience of this form of analysis.
Mal
Hans-Otto Baral,
27-01-2026 14:22
Re : DNA match
LSU is much less variable, so 3% mean very much. But you need to know which G. umbratile strain appeared. I see 4 in Genbank, one of which differs by 4% from the other 3.