Australian rainforests are highly diverse, with the subtropical forests of northern NSW being particularly rich in Gondwanan lineages. Unfortunately, during the last 150 years the impacts of logging, clearing and urbanisation have significantly reduced the extent of rainforest vegetation in Australia. This is particularly true for the Big Scrub of northern NSW (which covered an area of over 70,000 ha prior to European settlement) where widespread clearing has restricted lowland subtropical vegetation to approximately 1% of its original distribution.
In northern NSW, well over 100 rainforest plants have restricted distributions, are rare or even at risk of extinction. There can be many reasons why these species are rare: from recent habitat clearing and fragmentation, to more natural causes such as historical disturbance events, isolation and lack of dispersal mechanisms. Understanding how species respond to threats is crucial for conservation planning. Consequently, one of the main aims of our research is to help adjust management approaches to ever-changing threats.
Following are a few examples of our dedicated threatened species management research.
Augmented gene flow and genetic rescue
Many rare and threatened species are so restricted in numbers and so isolated, that they are low in diversity and risk inbreeding depression (the loss of reproductive capacity and fitness). Such species are at risk of extinction unless long-term management include genetic rescue.
Our research on the genetic diversity, ecology and dynamics of rare and threatened species enables us to develop management strategies and translocation plans that minimize kinship (relatedness), maximize diversity, re-establish fertility and increase overall viability. Some examples include: Elaeocarpus sedentarius, Elaeocarpus williamsianus, Fontainea oraria, Syzygium paniculatum and Uromyrtus australis.
New technologies to the rescue
In our research, we take advantage of the latest DNA-based technologies to guide conservation and management strategies. An example is the work on the genetics of the Wollemi Pine (Wollemia nobilis). Using new Next Generation Sequencing technology, we sequenced the entire chloroplast genome of most known Wollemi Pine individuals and discovered unexpected variation across the remaining populations.
Continuing from this preliminary work, we are now sequencing the transcriptome (the portion of the genome that is directly translated into RNA and proteins), searching for signs of variation within important regions of the genome. We are particularly interested in variation within resistance gene families since the few remaining wild Wollemi Pines are known to be susceptible to a range of common pathogens.
Some of our relevant publications:
- Greenfield A, McPherson H, Auld T, Delaney S, Offord CA, van der Merwe M, Yap JYS, Rossetto M (2016) Whole-chloroplast analysis as an approach for fine-tuning the preservation of a highly charismatic but critically endangered species, Wollemia nobilis (Araucariaceae). Australian Journal of Botany 64: 654-658.
- Yap JYS, Rohner T, Greenfield A, van der Merwe M, McPherson H, Glenn W, Kornfeld G, Marendy E, Pan AYH, Wilton A, Wilkins MR, Rossetto M, Delaney SK (2015) Complete chloroplast genome of the Wollemi pine (Wollemia nobilis): structure and evolution. PLoS ONE 10(6): e0128126
- Eliott FG, Shepherd M, Rossetto M, Bundock P, Rice N, Henry RJ (2014) Contrasting breeding systems revealed in the rainforest genus Davidsonia (Cunoniaceae): Can polyembryony turn the tables on rarity? Australian Journal of Botany 62: 451-464.
- Eliott FG, Connelly C, Rossetto M, Shepherd M, Rice N, Henry RJ (2013) Novel Microsatellite markers for the endangered Australian rainforest tree Davidsonia jerseyana (Cunoniaceae) and cross-species amplification in the Davidsonia genus. Conservation Genetics Resources 5: 161-164.
- Thurlby KAG, Wilson PG, Sherwin WB, Connelly C, Rossetto M (2012) Reproductive bet-hedging in a rare yet widespread rainforest tree, Syzygium paniculatum (Myrtaceae). Austral Ecology 37: 936-944.
- Thurlby KAG, Connelly C, Wilson PG, Rossetto M (2011) Development of microsatellite loci for Syzygium paniculatum (Myrtaceae), a rare polyembryonic rainforest tree. Conservation Genetics Resources 3(2): 205-208.
- Kooyman R, Rossetto M (2008) Definition of plant functional groups for informing implementation scenarios in resource-limited multi-species recovery planning. Biodiversity and Conservation 17: 2917-2937.
- Rossetto M, Kooyman R, Sherwin W, Jones R (2008) Dispersal limitations, rather than bottlenecks or habitat specificity, can restrict the distribution of rare and endemic rainforest trees. American Journal of Botany 95:321-329.
- Maynard D, Crayn D, Rossetto M, Kooyman R, Coode M (2008) Elaeocarpus sedentarius sp. nov. (Elaeocarpaceae) – morphometric analysis of a new, rare species from eastern Australia. Australian Systematic Botany 21: 192-200.
- Rossetto M (2008) From populations to communities: understanding changes in rainforest diversity through the integration of molecular, ecological and environmental data. Telopea 12(1): 47-58.
- Kooyman R, Rossetto M (2006) Factors influencing species selection for littoral rainforest restoration: do environmental parameters matter? Ecological Management & Restoration 7(2): 113-122.
- Rossetto M (2005) A simple molecular approach for identifying a rare Acronychia (Rutaceae) provides new insights on its multiple hybrid origins. Biological Conservation 121(1): 35-43.
- Rossetto M, Kooyman RM (2005) The tension between dispersal and persistence regulates the current distribution of rare paleo-endemic rainforest flora: a case study. Journal of Ecology 93: 906-917.
- Taylor KJ, Lowe AJ, Hunter RJ, Ridgway T, Gresshoff PM, Rossetto M (2005) Genetic diversity and regional identity in the Australian remnant Nothofagus moorei. Australian Journal of Botany 53: 437-444.
- Vallee L, Hogbin T, Monks L, Makinson B, Matthes M, Rossetto M (2004) Guidelines for the Translocation of Threatened Plants in Australia. Second Edition (80 pages). Australian Network for Plant Conservation, Canberra.
- Rossetto M, Gross CL, Jones R, Hunter J (2004) The impact of clonality on an endangered tree (Elaeocarpus williamsianus) in a fragmented rainforest. Biological Conservation 117(1): 33-39.
- Rossetto M, McNally J, Henry RJ, Hunter J, Matthes M (2000) Conservation genetics of an endangered rainforest tree (Fontainea oraria - Euphorbiaceae) and implications for closely related species. Conservation Genetics 1 (3): 217-229.