Taxacom: Barcodes and species

[Marko Prous]

Dear John,

It's possible to have identical barcodes (mitochondrial COI fragment) 
between species, which can be quite common in some groups (sawflies), 
rare in Lepidoptera. You should check also few nuclear genes (or maybe 
even just one might be enough). If these correlate with morphological 
differences, good chance that these are different species despite of 
identical mitochondrial barcodes.

Occasional hybridization or incomplete lineage sorting can explain this, 
but if nuclear genes clearly separate the species, mitochondrial 
introgression would be more likely explanation (mitochondrial DNA 
evolves faster than nuclear DNA).

cheers,
Marko

On 5/19/24 09:07, John Grehan via Taxacom wrote:
> As I am pretty ignorant of technical details of species designation and
> barcode identity, I would be grateful for any feedback on whether it is
> possible for two 'species' to have identical 'barcodes' (never liked that
> label with its essentialist connotations).
>
> I have a colleague who has collected some ghost moths from the same date
> and location. There are two morphs - for simplicity 'white spot' and
> 'plain'. Dissections of genitalia also show differences, with the white
> spot and plain each showing consistent differences, although only 2
> specimens for white spot and 3 for plain. Even with this small sample I am
> kind of intrigued that the external difference matches the internal
> difference.
>
> The genitalic differences are prominent enough that I would normally view
> them as indicative of species difference. Perhaps there is a single
> polymorphic species, but correlated external and internal differences were
> a bit of a surprise. Any comments or enlightenment would be very welcome.
>
> Cheers, John
>