North American Population
When three populations were defined in North America (Eastern US, Middle
US and Western US) there is no distinct population structure based on
the F ST analysis. The comparison of these three
regions shows little genetic differentiation (Table 3). These findings
are consistent with an earlier investigation of this population, which
found that there was no population structure based on allozyme data in
the North American starling population (Cabe, 1998). Banding efforts in
North America have shown that the starlings are found to migrate in
unpredictable ways, not always in the North and South direction, but
also in the East and West directions (Brewer, 2000). The absence of the
population subdivision in North America is likely due to the high
dispersal rates and the unpredictable and latitudinal migration
patterns.
Since the introduction of European starlings into North America, novel
haplotypes may have arisen, in addition to the native range haplotypes
identified here (Figure 4). These haplotypes are UKK, UKC and UKE as
described in the native population sampled from Monks Wood, UK (Rollins
et al, 2011). However, because our native-range data are limited, it is
likely that there are more shared haplotypes between North America and
the UK than we have identified. Remarkably little is known about
starling population genetics in the native range.
Consistent with our findings based on mitochondrial data, a recent study
using genome-wide SNPs to investigate North American starlings did not
find evidence of population structure (Hofmeister et al., 2019).
However, those data do indicate that there are genotypes associated with
specific environmental features such as precipitation and/or
temperature. This suggests that over time, population structure may
develop in this invasive population, despite apparent high levels of
dispersal.