Discussion
Our work has leveraged an extremely rare genetic dataset before, during
and after a subdivision event, to demonstrate that in any such event,
whether natural or artificial, important genetic changes can occur very
rapidly. We also show how to monitor this. In particular, this study
revealed several insights about the genetic consequences of habitat
fragmentation by linear infrastructure using an extensive pre- and
post-construction SNP dataset on koalas. Firstly, we found that evidence
for an immediate genetic signal was present but metrics’ dependant.
Secondly, we show how the population subdivision as a result of the
linear transport infrastructure project, will result in an increased
rate of genetic diversity loss over time as a consequence of genetic
drift, specifically for the population located above the linear
transport infrastructure. This longer-term genetic consequence is an
important aspect to consider when managing populations impacted by
linear infrastructure projects.
Last, using forward dispersal
simulations, we show that a
minimum of 8 koalas would need to be dispersing per generation from each
side of the linear transport infrastructure to maintain genetic
differentiation close to zero (e.g. low Fst < 0.05; (Lloydet al. 2013)) while 16 koalas would represent best case scenario
given both genetic differentiation and genetic diversity would remain
unchanged for both populations of koalas over the next 10 generations
(e.g. 60 years).