Abstract
Anthropogenic biological invasions represent major concerns but enable
us to investigate rapid evolutionary changes and adaptation to novel
environments. The goldfish Carassius auratus with sexual diploids
and asexual triploids coexisting
in natural waters, is one of the most widespread invasive fishes in
Tibet, providing an ideal model to study evolutionary processes during
invasion in different reproductive forms from the same vertebrate. Here,
using whole-genome resequencing data of 151 C. auratusindividuals from invasive and native ranges, we found different patterns
of genomic responses between diploid and triploid populations during
their invasion to Tibet. For diploids, although invasive individuals
derived from two different genetically distinct sources and had a
relative higher diversity (π) at the population level, their individual
genetic diversity (genome-wide observed heterozygosity) was
significantly lower (21.4%) than that of source individuals. Population
structure analysis revealed that the invasive individuals formed a
specific genetic cluster distinct from the source populations. Runs of
homozygosity analysis showed low inbreeding only in invasive
individuals, and only the invasive population experienced a recent
decline in effective population size reflecting founder events. For
triploids, however, invasive populations showed no loss of individual
genetic diversity and no genetic differentiation relative to source
populations. Regions of putative selective sweeps between invasive and
source populations of diploids mainly involved genes associated with
mannosidase activity and embryo development. Our results suggest
invasive diploids deriving from distinct sources still lost individual
genetic diversity resulting from recent inbreeding and founder events
and selective sweeps, and invasive triploids experienced no genetic
change owing to their reproduction mode of gynogenesis that precludes
inbreeding and founder effects and may make them more powerful invaders.
Keywords : Genetic response, biological invasion,Carassius auratus , ploidy, Tibet, selective sweep