4 Discussion
The results of our study document a highly different genetic and
phylogeographic structure of diploid and triploid goldfish, particularly
reflected in a clear geographic structure in diploids and no obvious
association between structure and geographical origin in triploids.
Also, and in accordance with our main hypothesis, we found a major
difference in patterns of genetic variation between invasive populations
of diploids and triploids in Tibet, with decreased variation in diploids
and evidence for recent population decline reflecting founder events,
but in contrast no detectable loss of variation in triploids.
Nevertheless, inbreeding was low in diploids suggesting that multiple
introductions from diverse sources have buffered bottlenecks associated
with founding. Finally, we found evidence for selective sweeps in
invasive diploid goldfish, with genes within outlier regions enriched
for functions related to mannosidase activity and embryo development. We
discuss these findings in more detail below.