Estimating the longer-term genetic consequences of linear transport infrastructure.
We compared the predicted loss of genetic diversity for the two fragmented populations (above, below) with the predicted loss of genetic diversity for the population if the population had not been fragmented (pre, post). This allowed us to assess the predicted long-term consequences of linear transport infrastructure on the populations’ genetic diversity. To do this, we forecast the extent of genetic diversity loss across generations using the following equation:
\begin{equation} {H\mathrm{e}}^{t}=H\mathrm{e}\ {(1-\frac{1}{2N\mathrm{e}})}^{t}\nonumber \\ \end{equation}
where He is Hardy-Weinberg expected heterozygosity, Ne is effective population size and t in the number of generations. Estimated generation time in koalas is 6 years (Phillips 2000). We adjusted Ne for the proportion of males within a population that sire offspring (~30%) which was estimated from Schultz et al (2020)’s study. We also generated the same analysis using the Shannon’s diversity index (see Appendix 1, Figure S1).