Abstract

The Eurasian spruce bark beetle, Ips typographus, is a major pest, capable of killing spruce forests during large population outbreaks. Recorded dispersal distances of individual beetles are typically within hundreds of meters or a few kilometers. However, the connectivity between populations at larger distances and longer time spans and how this is affected by the habitat is less studied, despite its importance for understanding at which distances local outbreaks may spread. Previous population genetic studies in I. typographus typically used low resolution markers. Here, we use genome-wide data to assess population structure and connectivity of I. typographus in Sweden. We used 152 individuals from 19 population samples, distributed over 830 km from Stromsund (63 degrees 46 ' 8 '' N) in the north to Nyteboda (56 degrees 8 ' 50 '' N) in the south, to capture processes at a large regional scale, and a transect sampling design adjacent to a recent outbreak to capture processes at a smaller scale (76 km). Using restriction site-associated DNA sequencing (RADseq) markers capturing 1409-1997 SNPs throughout the genome, we document a weak genetic structure over the large scale, potentially indicative of high connectivity with extensive gene flow. No differentiation was detected at the smaller scale. We find indications of isolation-by-distance both for relative (F-ST) and absolute divergence (Dxy). The two northernmost populations are most differentiated from the remaining populations, and diverge in parallel to the southern populations for a set of outlier loci. In conclusion, the population structure of I. typographus in Sweden is weak, suggesting a high capacity to disperse and establish outbreak populations in new territories.

Keywords

bark beetle; connectivity; gene flow; Ips typographus; migration; pest management; population structure

Published in

Ecology and Evolution
2022, Volume: 12, number: 7, article number: e9078
Publisher: WILEY

SLU Authors

• Choudhary, Shruti

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    
  • Lund University

• Schlyter, Fredrik

  • Department of Plant Protection Biology, Swedish University of Agricultural Sciences
    
  • University of the Sunshine Coast

Associated SLU-program

SLU Plant Protection Network
SLU Forest Damage Center


UKÄ Subject classification

Evolutionary Biology
Genetics
Ecology


Publication identifier

DOI: https://doi.org/10.1002/ece3.9078

Permanent link to this page (URI)

https://res.slu.se/id/publ/123080