Land availability may be more important than genetic diversity in the range shift response of a widely distributed eucalypt, Eucalyptus melliodora

Climate change is challenging many species which are expected to respond through range shifts, in situ adaptation or extinction. Successful plant migration is complex and dependent on many factors including propagule availability, dispersal ability, regeneration sensitivity and habitat suitability. Eucalypts are a common and key component of the Australian flora that have been extensively cleared in south eastern Australia. Under a warming climate eucalypts in this region are predicted to contract and move in a south easterly direction. We used microsatellites to evaluate genetic diversity and population genetic structure in 32 mature stands of Yellow Box (Eucalyptus melliodora) from across the known distribution. We also used niche modelling to explore Yellow Box range shifts from the Last Glacial Maximum (21 Kya) to 2090. We found high genetic diversity, no evidence of genetic bottlenecks and limited population genetic structure suggesting that old Yellow Box trees are remnants of a once large panmictic population. Niche modelling found that habitat suitability in coastal and mountainous areas will become available under a warming climate, especially at higher elevations. While we predict that habitat suitable for Yellow Box colonisation will become available when this was considered in conjunction with land availability opportunities for colonisation will be significantly diminished.