open access

https://hdl.handle.net/2115/92978

Population stability and asymmetric migration of caddisfly populations, Stenopsyche marmorata (Stenopsychidae), in a forest-agriculture landscape

英語

Anthropogenic impacts

2023-08-23

Springer

Aquatic sciences

85

In river systems, frequent floods generally decrease the abundance of riverine species, and recent studies have reported that the degree of flood disturbance changes along agricultural gradients. However, the interactive impacts between anthropogenic and flood disturbances on migration dynamics are not well tested. In a forest-agricultural landscape in northern Japan, we observed the population stability (fluctuations in abundances) and migration dynamics (directional gene flow) of a net-spinning caddisfly Stenopsyche marmorata (Stenopsychidae), throughout the snowmelt flood period to test whether (1) population stability decreases along agricultural gradients, (2) asymmetric migration occurs from stable populations in forested streams to unstable populations in agriculturally altered streams, and (3) genetic diversity is higher in stable populations. The abundance of S. marmorata was related to agricultural development (i.e., pasture cover in catchments); its abundance was higher in agricultural streams before the flood (March), but the quantitative relationship was inverted just after the flood (May) and recovered six months post-flood (November). The resistance index (post-flood abundance divided by pre-flood abundance) showed a negative correlation with pasture cover in the catchment, indicating that population stability decreases along agricultural gradients. The long-term effective number of migrants (Nem) and recent migrants (assignment tests) estimated from the genetic analysis showed asymmetric colonization from stable populations in forested sites to unstable populations in agricultural sites. In contrast, genetic diversity was not related to agricultural development, but private allelic richness (number of unique alleles) was higher in forested streams than in agricultural streams. Our findings suggest that forested streams serve as sources for unstable populations in agriculturally impacted streams and contribute to high genetic diversity at a catchment scale.

学術雑誌論文

Accepted Manuscript

This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: http://dx.doi.org/10.1007/s00027-023-00992-6

1015-1621