# Population Genomics of a Rare and a Common Wood–Inhabiting Fungal Species Across Europe

## TL;DR

This study explores the genetic structure of two wood-inhabiting fungi across Europe to inform conservation strategies.

## Contribution

The study provides new insights into the genetic connectivity of rare and common fungi, linking dispersal patterns to conservation needs.

## Key findings

- Antrodiella citrinella shows very weak population structure, indicating wide dispersal and gene flow.
- Fomitopsis pinicola has two moderately differentiated populations, possibly due to dispersal limitations and historical forest use.

## Abstract

Many species have become threatened during the Anthropocene, requiring conservation strategies based on biological evidence. Wood‐inhabiting fungi face multiple threats due to a complex interplay of a short lifespan, removal of dead wood as a resource and climate change. Furthermore, rare fruiting events might restrict dispersal via spores, leading to a significant population genetic structure. Yet, little is known about the genetic structure of both rare and common wood‐inhabiting fungal species across Europe. Here, we investigate the rare polypore fungus Antrodiella citrinella, which co‐occurs with the common wood‐decay fungus Fomitopsis pinicola. We analysed a total of 149 individuals of both species across 13 countries, sequenced their genomes and analysed single‐nucleotide polymorphisms. Based on a broad set of analyses, we found a very weak population structure in
A. citrinella, suggesting historically wide dispersal and effective gene flow across Europe. In contrast, we found support for two moderately differentiated populations following a southwest‐northeast separation in
F. pinicola, possibly due to dispersal limitation through its relatively larger spores, a more intense forest use history in southern Europe and a post‐glacial history of co‐immigration with the main host tree species, Norway spruce. While the weak to moderate genetic structure of wood‐inhabiting fungi suggests historically sufficient habitat connectivity, conservation measures should consider strategies providing deadwood as an important habitat to restore and maintain connectivity throughout Europe.