Time flies, or the future of an Extinct in the Wild tree rediscovered

If you are like me, you will be astonished to discover that it is already March and before we noticed, Easter is a step away and the MSc in Plant Diversity at the University of Reading quickly moving forward. After six challenging months of hard and humbling work, it is now time to focus on my final research project, to be concluded next September, 2016. Personally, this represents the chance to oversee a conservation project from the initial set up to the delivery stages, enabling me to build my academic credentials by applying my previous experience in a real-world, multifaceted situation. On this regard, recent evidence has revealed an unprecedented loss of biodiversity in Earth`s history, what has led scientists to now declare the sixth mass extinction era (Ceballos et al., 2015). Indeed, we are all well aware that extinction is forever and who is the main responsible for speeding up the pace toward this irreversible scenario, where current rates of species loss are commonly associated with threats arising from unsustainable human activities. Extinction is irreversible and reduces the biological heritage of the Earth. Although processes of extinction and appearance of new species are frequent and inherent to geological and biological evolution, the current accelerated trend of biodiversity loss is something far more serious than previous natural events. Nonetheless, with this in mind, disclosing with accuracy how complex organisms would respond to certain events, establishing extinction is imprecise, and thus species thought to be extinct are rediscovered with an intriguing frequency. This is especially true for groups with elusive habits or odd life cycles and ecological requirements, particularly plants. In fact, Penedo et al (2015) claim that, in practice, it is impossible to be certain that the last individual of a plant species has died - mainly in megadiverse countries such as Brazil, where extensive areas are insufficiently inventoried and several plant groups are understudied. Diamond (1987) had already argued the difficulty in robustly establishing extinction of a given taxon. In a recent effort, Scheffers and collaborators (2011) compiled 351 rediscovered amphibians, birds and mammals, corroborating Diamond's work and highlighting the small and declining remaining populations of these rediscovered taxa.. This frequent and misleading approach in predicting extinction by assumption was named by Collar (1998) as the Romeo Error, very common for flora species. Clearly, errors in judgement are far from uncommon. Every few years a species thought to be extinct or even officially declared as such, turns up unexpectedly in the wild. This makes it a so-called “Lazarus” species – and there are many examples around (lazarus species, extinct plants rediscovered). In light of this current and pressing issue, I would like to use this post to bring your attention to a tree species of which I will be carrying out research on as part of my MSc thesis. The research is supervised by Dr Eimear Nic Lughadha (RBG Kew) and Professor Julie H. Hawkins (UoR) in partnership with Dr Gustavo Martinelli, my former supervisor in Brazil and the director of the Brazilian National Centre for Plant Conservation - CNCFlora, in Rio de Janeiro Botanic Garden.

The target species of my research project is the magnificent Guarajuba, Terminalia acuminata (Allemão) Eichler, which represents one of the most recent Lazarus species cases in Brazil. This elusive tree is a Mata Atlantica Hotspot`s endemic and was the first Brazilian plant declared extinct in the Wild (EW) by the IUCN (Silva, 1998), after more than 70 years without records in the wild. T. acuminata was once a common massive tree (sometimes reaching 25 m) from lowland and montane Atlantic Rainforest in Rio de Janeiro State (Allemão, 1844). After being historically over-exploited for its valuable timber, frequently used in general carpentry and boat building, the species was relentlessly logged down and the second biggest city in Brazil grew exponentially exactly where T. acuminata's core area of distribution was located.

Despite 5 individuals known to be growing in Rio de Janeiro Botanic Garden, the species was absent in the wild until 2015, when my former team at the Brazilian National Centre for Plant Conservation – CNCFlora finally founded it once again. The rediscovery of this enigmatic species shocked the Brazilian conservation community, and raised important questions about specimen collection strategies and the validity of specimen-based assessment of conservation status.

Terminalia acuminata rediscovery in 2015. A 18 m -tall mature individual was collected with fruits (greenish samaras) (Photo: Lucas Moraes - CNCFlora/ JBRJ).

Additionally, the case study of T. acuminata will help to more clearly understand the declaration of extinction, and the fate of rediscovered plants. Unfortunately, the current status of the species is among the “living dead” (Jenzen, 2001): its population is not expected to thrive without urgent, significant human intervention. Regardless of this its occurrence  in one of the most depleted biomes across the globe, the Atlantic Rainforest Hotspot (Mittermeier et al., 2004), I strongly believe that further studies such as the one I am currently performing will contribute to species` conservation and effective protection/ management action plans. Although long-lived trees such as T. acuminata are, a priority, relatively more resistant to the effects of fragmentation, the impacts of depletion of its habitat may affects its breeding pattern, reproductive output and progeny fitness, directly affecting population viability in the long term. The conservation community needs a much clearer understanding of why rediscovered species were initially declared extinct and whether rediscovered populations might be viable. The present case study represents the chance to test species-specific emergence approach,  which may be useful for many other plants  in similar situations, particularly in the tropics. These are together urgently needed, not solely for Guarajuba, but for hundreds of other species which are ultimately in worse situations. This means, it is expected that we will be able to both inform conservation action and ensure checklists and red lists are accurate. 

The next step at this stage will take place in situ. The lack of primary data for this species has motivated the organization of a 20 days expedition in order to gather information on distribution, population size, age structure, genetic diversity, population genetics and threats affecting species’ persistence. I hope that with this set of information on hand it will be possible to increase our understanding of such a shrinking species, reassessing its extinction risk status and helping to design an action plan to save it from the verge of extinction. Below, are the sites which will be visited during the fieldwork, areas where species occurrence is confirmed and others where they are potentially still growing.

Finally, I am hopeful to expect that the outcomes of the present work will help to build a feasible participatory conservation plan that will be beneficial for both communities, managers, decision makers, scientists and plant conservationists as a whole in Brazil. I look forward to being part of the possible future of such a charismatic and intriguing tree!

References

Allemão y Cysneiros, F.F. 1844. Plantas Novas do Brasil.

Ceballos, G., Ehrlich, P.R, Barnosky, A.D, Garcia, A., Pringle, R.M,. Palmer, T.M. 2015. Accelerated modern human-induced species losses: Entering the sixth mass extinction. Science Advances 1(5).

Collar, N.J. 1998. Extinction by assumption; or, the Romeo Error on Cebu. Oryx 32: 239-244

Diamond, J.M. 1987. Extant unless proven extinct? Or, extinct unless proven extant? Conservation Biology 1:77-79.

Penedo, T.S.A., Moraes, M.A.,   Borges, R.A.X., Maurenza, D., Judice, D.M., Matinelli, G. 2015. Considerations on extinct species of the Brazilian flora. Rodriguésia 66(3): 711-715

Mittermeier R.A, Gil P.R, Hoffmann M., Pilgrim J., Brooks T, Mittermeier C.G., Lamoreux J, Fonseca G.A.B.2005. Hotspots revisited: earth’s biologically richest and most endangered terrestrial ecoregions, 2nd edn. CEMEX, Mexico City.

Janzen, D.H. 2001. Latent extinctions – the Living Dead, in Levin, S.A. (ed.). Encyclopedia of Biodiversity vol. 3. Academic Press, New York, 689–699.

Scheffers, BR, Yong, DL, Harris, JBC, Giam, X, Sodhi, NS (2011) The world`s rediscovered species: back from the brink? PlosPOne DOI: 10.1371

Silva, N.M.F. 1998. Terminalia acuminata. The IUCN Red List of Threatened Species 1998: .T37996A10087533. http://dx.doi.org/10.2305/IUCN.UK.1998.RLTS.T37996A10087533.en . Downloaded on 04 November 2015

Stace, C. 2010. Combretaceae In: Flora Neotropica 107, The New York Botanical Garden Press, 374 p