2.1 Sample collection and whole-genome sequencing
In the invasive range, a total of 62 C. auratus juveniles with an
average weight of 2.9 g were collected in 2019 from the Lala (LL) and
Chabalang (CBL) wetlands within the Yarlung Zangbo River basin in Tibet
(Table 1). In the native range, 73 C. auratus adults were
collected in 2015-2021 from 11 sites belonging to five river systems,
including the Yangtze River (SC, Sichuan; SS, Shishou; ZDL, Zhangdu
lake; CL, Chao lake; TH, Tai lake), Yellow River (NX, Ningxia), Huai
River (RR, Ru River; HZL, Hongze lake), Songhua River (DQ, Daqing; JPL,
Jingpo lake) and Pearl River (WR, You River). As the Ningxia and Sichuan
regions assumed to be the sources of goldfish introduced into Tibet,
samples were collected from these two regions across a wide geographical
range; the coordinate of each sample can be found in Table S1. Here
populations and individuals sampled from invasive and native ranges are
denoted “invasive” and “native” populations and individuals,
respectively. A small piece of fin tissue was sampled from each fish
individual and stored in absolute ethanol until DNA extraction.
Genomic DNA was extracted from fin clips using a phenol-chloroform
method (Taggart et al., 1992). At least 0.5 μg of genomic DNA from each
sample was used to construct the resequencing library with an insert
size of ~350 bp using the NEBNext Ultra DNA Library Prep
Kit for 150 bp paired-end sequencing on the Illumina X Ten platform
(Illumina USA). Sequencing was outsourced to Biomarker Technologies
Corporation (Beijing, China). In addition, resequencing data of 16
individuals from the native range were downloaded from a previous study
(Chen et al., 2020). A total of 151 goldfish genomes were included in
this study. Additional information of each sample is shown in Table S1.