Weak population genetic structure in Eurasian spruce bark beetle over large regional scales in Sweden. Issue 7 (6th July 2022)

• Record Type: Journal Article
• Authors: Ellerstrand, Simon Jacobsen; Choudhury, Shruti; Svensson, Kajsa; Andersson, Martin N.; Kirkeby, Carsten; Powell, Daniel; Schlyter, Fredrik; Jönsson, Anna Maria; Brydegaard, Mikkel; Hansson, Bengt; Runemark, Anna
• Is Part Of: Ecology and evolution. Volume 12:Issue 7(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-07-06
• Subjects: bark beetle -- connectivity -- gene flow -- Ips typographus -- migration -- pest management -- population structure; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.9078
• Languages: English
• ISSNs: 2045-7758

Abstract

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 Strömsund (63° 46′ 8″ N) in the north to Nyteboda (56° 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. Abstract : We investigated the genetic structure of the Eurasian spruce bark beetles over 800 km in Sweden using Restriction site associated DNA yielding thousands of markers across the genome. Our study show that population structure over this scale is weak, but we find indications of isolation by distance and that the Northern populations tended to be differentiated from the Southern ones.