The tension between dispersal and persistence regulates the current distribution of rare palaeo-endemic rain forest flora: a case study

Authors


Maurizio Rossetto (tel. + 61 29231 8337; fax: + 61 29251 4403; e-mail: maurizio.rossetto@rbgsyd.nsw.gov.au).

Summary

  • 1Eidothea hardeniana (Proteaceae) is a narrow endemic representative of an ancient lineage restricted to a single site in northern New South Wales (Australia). This study aims to identify the life-history traits most likely to have influenced the current distribution pattern of this rain forest tree.
  • 2Using ecological and molecular analyses we found that its range is limited by the absence of efficient dispersal mechanisms rather than by habitat availability, or as a result of a recent bottleneck or of reproductive failure.
  • 3Resprouts can take over the position of senesced plants, even in the absence of disturbance, allowing local persistence and the maintenance of genetic diversity. Long-term persistence and preferential outcrossing further favour relatively high levels of diversity (HE = 0.542) despite a small effective population size (Ne = 21.6).
  • 4We used eight life-history traits to assess if the E. hardeniana findings were valid across 258 local taxa. Current distribution patterns of rain forest species within a species-rich community were accounted for by linking two important components of community assembly theory: dispersal and niche assembly.
  • 5The interaction of the seed-based dispersal dimension and resprouting potential best explains the current distribution of rare local taxa. Major dimensions of life-history trait variation were identified among local plant species, suggesting that a range of interacting traits contribute to a species’ response to environmental variables and mitigate the influence of potentially adverse circumstances.
  • 6The benefits of merging ecological and genetic approaches to interpret species distribution and population structure are applicable across a broader range of studies. Our findings highlight how currently constrained palaeo-endemic species with small populations in refugial habitats may retain the capacity to both persist and expand in response to changing circumstances and opportunities. This has important implications for species conservation, habitat management and reserve design.

Ancillary