Patterns of genetic diversity and differentiation.
We found that each of the disturbance processes (natural vs linear
transport infrastructure) resulted in a significant decrease in allelic
richness (\({}^{0}D\)) but saw no changes in Ho,
He, \({}^{1}D\) and\({}^{2}D\) (see Table 1). The
population decline caused by ‘natural’ mortality events resulted in a
significant loss in \({}^{0}D\) (Wilcoxon test: \({}^{0}D\_dataset1\)vs \({}^{0}{D\_}dataset2\), p-value < 0.0001). This was also
the case for the subsequent population decline caused by the linear
transport infrastructure project (Wilcoxon test;\({}^{0}D\_dataset2\)vs \({}^{0}{D\_}dataset3\_above\), p-value < 0.0001;\({}^{0}D\_dataset2\) vs \({}^{0}{D\_}dataset3\_below\), p-value
< 0.0001). Importantly, the subdivision caused by the linear
transport infrastructure resulted in the population of koalas located
above the linear transport infrastructure having a significantly smaller\({}^{0}D\) than its neighbouring population of koalas located below
the linear transport infrastructure (Wilcoxon test:\({}^{0}D\_dataset3\_above\) vs \({}^{0}{D\_}dataset3\_below\),
p-value < 0.0001). It is also important to note that the
percentage of monomorphic loci increased at each stage of the
disturbance process: from 1.07% to 2.65% because of the population
decline caused by ‘natural’ mortality events, and from 2.65% to 8.07%
(above) and 4.27% (below) because of the subsequent population decline
caused by the linear transport infrastructure project (i.e.
translocations and population subdivision, Table 1). The extent of
genetic differentiation between those genetic datasets, however, was
negligible (Appendix 1, Table S1).