Local climate adaptation and gene flow in the native range of two co-occurring fruit moths with contrasting invasiveness

Invasive species pose increasing threats to global biodiversity and
ecosystems. While previous studies have characterized successful invaders
from ecological traits, characteristics related to evolutionary processes
have rarely been investigated. Here we compared gene flow and local
adaptation using demographic analyses and outlier tests in two
co-occurring moth pests across their common native range of China, one of
which (the peach fruit moth, Carposina sasakii) has maintained its native
distribution, while the other (the oriental fruit moth, Grapholita
molesta) has expanded its range globally during the past century. We found
that both species showed a pattern of genetic differentiation and an
evolutionary history consistent with a common southwestern origin and
northward expansion in their native range. However, for the noninvasive
species, genetic differentiation was closely aligned with the environment,
and there was a relatively low level of gene flow, whereas in the invasive
species, genetic differentiation was associated with geography. Genome
scans indicated stronger patterns of climate-associated loci in the
noninvasive species. While strong local adaptation and reduced gene flow
across its native range may have decreased the invasiveness of C. sasakii,
this requires further validation with additional comparisons of invasive
and non-invasive species across their native range.