This study investigates whether niche partitioning into upland and riparian habitats differentiates the range dynamics of two closely related and sympatric eastern Australian trees (Tristaniopsis collina, T. laurina) that share similar dispersal mechanisms.
We found significant environmental niche differentiation between species. Genetic signatures in T. laurina (Kanooka, Water Gum) suggest long-term local persistence and geographic isolation among populations, while in Tristaniopsis collina (Mountain Water Gum, Hill Kanuka) they suggest recent and rapid range expansion. We suggest that dispersal and colonization in T. laurina is primarily limited by its specialized recruitment traits (adapted to flood disturbance regimes) rather than habitat availability or bioclimatic preferences. In contrast, T. collina appears to have greater capacity for range expansion, but a poorer persistence potential.
Currently the study is being expanded across the entire distribution of these two species. We are using whole genome scans to identify potential adaptive genes that differ in distribution among these two often co-distributed sister species.