Hello Magnus,

Thanks for contacting me. We are trapping and collecting faeces monthly on bank voles and tundra voles (however, we haven’t observed much tundra voles since before Christmas). The plan is to analyse this using next-gen metabarcoding. I don’t think we have much grey-sided voles here so we will not be able to compare their diets with my study area. How are the vole populations keeping up around you these days?

Cheers,

Mage

Hi Magne,

Ok, sounds interesting. We have not been using feaces for metabarcoding yet but discussed it. Can you get any quantititive data out from the feces?

We have been trapping during the whole winter in a winter project and it seems like the vole populations are quite strong locally but in some areas it is in contrast very low densities. We will get better information of the status during the normal trappings within the environmental monitoring later this spring when the snow has melted.

Best Magnus

About quantitive data it depends on what you mean. I'm only a novice, but as far as I understand it is very uncertain to convert number of sequence reads into biomass when comparing different samples because there are just way too many biases on several stages. Though some designs seems to be able to convert the relative proportions of reads into the diets relative proportions fairly well, at least within one primer. We have done a test on this with the plant primer gh, but I'm diving into the bioinformatics next week so I don't know anything about how it went yet :-) But even if the PCR and sequencing biases get better you are in both cases left with variation in amount of DNA between species and in different parts of individuals (e.g. bark vs. green leaf). There is a newly published meta-analysis on this aspect you may want to check out: Article How quantitative is metabarcoding: A meta‐analytical approach

Interesting to hear about your local population!

Thanks for the answer. Yes, it seems quite difficult retrieving, reliable quantitative data at the moment but maybe there are ways as you say with using relative proportions. Keep me updated about the progress of your project - I find it really interesting.