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considered can cause the 
abundance and distribution of the species to expand, 
reducing or even completely suppressing its rarity. 
Livro vermelho da flora do Brasil \u2013 Plantas raras do Cerrado | 19 
Finally, apart from epistemological discussions on 
the species and independently of their circumscription 
\u2013 wider or more restricted \u2013 the fact is that now, at 
this exact moment, there exist plants in nature that are 
under various threats of extinction. It is also a fact that 
such threats apply more seriously to species represented 
by few individual organisms or by a more restricted 
geographical distribution. It is these species, the rare 
ones, that are the focus of our discussion. 
Why conserve rare species?
Seen under a broader dimension, the reasons for conserving rare species are exactly the same as those used to justify the conservation of any spe-
cies. It just happens that in the case of rare species, the 
justifications are strengthened and intensified by their 
very condition of rarity. 
We should conserve for a wide range of reasons, 
from a pragmatic and utilitarian perspective, to others 
of a more profound and ethical nature. In this context 
\u2013 and in a more egoistic interpretation \u2013 we can ar-
gue that such species represent a future potential for the 
discovery of new drugs, medications, or as food source 
to be used by future generations. In other words, we 
conserve because of the utility that such species could 
come to represent for our own species \u2013 a justification 
perhaps less noble in the eyes of many, but sufficiently 
realistic and effective. 
For above and beyond this anthropocentric per-
spective, there exists the justification that rare species 
can perform an ecological role so meaningful that 
their extinction would represent a significant degree 
of imbalance in the ecosystems they inhabit. They are 
the so-called keystone species, which perform a criti-
cal function in the maintenance of a community or 
ecosystem and whose impact is disproportional to that 
expected when only taking into account its relative 
Independently of constituting, or not, a keystone 
species in a given ecosystem, it is a fact that rare spe-
cies, like any other, possess ecological significance in the 
dynamic equilibrium of the communities in which they 
are encountered, to the extent that the loss of such spe-
cies also represents the loss of the ecological functions 
it performs. 
Further to the ecological factor, the conservation 
of rare species also finds support in evolutionary argu-
ments. These species evolved in a specific environmen-
tal context, and today are the result of numerous events 
of adaptation and natural selection, the history of which 
must be conserved, principally if we consider that they 
are represented by few individual organisms. Raphael & 
Marcot (2007) postulate that such species can become 
the basis for unexpected adaptive radiations, in a future 
and predictable horizon of environmental changes. 
In this same line of discussion, one can position rare 
species in two distinct evolutionary scenarios. In the 
first, we can suppose that a particular rare species is the 
result of recent processes of speciation and that, because 
of this, its individuals do not get widely dispersed in the 
various and possible areas they could occupy. Extinction 
would represent, in this case, the elimination of a lineage 
recently born, which could later originate various other 
lineages, thus contributing to maintaining and increas-
ing the biological diversity. It would be the elimination 
of a future possibility. 
In another scenario, we could imagine that this rare 
species is the last remaining of a lineage that was once 
richer and more diverse. It has experienced, therefore, 
numerous processes, and countless changes, that have 
resulted in the permanence of this lineage until today. 
Its extinction would represent, therefore, the elimina-
tion of the past and its historical legacy. 
Lastly, a final argument for conserving rare species: 
because they have exactly the same right of existence as 
any other species, including our own. This is a profound 
and ethical question that demands more than reflection, 
it demands attitude. 
Conservation of rare species in Brazil 
Brazilian flora includes more than 40,000 species of plants and over 6,000 species of fungus (Lista de espécies da flora do Brasil, 2014). of these, 
around 32,000 species are angiospermae (flowering 
plants), representing approximately 14% of the 223,000 
phanerogams (plants with seeds) estimated for the plan-
et by Scotland & Wortley (2003). 
The Catálogo de plantas raras do Brasil (Catalog of Rare 
Plants of Brazil) lists 2,291 species (Giulietti et al., 2009), 
meaning that around 7% of our flora is considered to be 
rare, the majority of which is concentrated in areas of 
the Savannah (Cerrado). Fire, mining, expansion of the 
agricultural frontiers and occupation by cattle are some 
of the factors that constitute threats to the rare species 
of the Savannah. These activities result in loss or deg-
radation of the habitats in which the species live. It is 
not surprising that this biome is considered a \u201chotspot\u201d 
for conservation (Myers, 2000), for its abundance, for 
the number of endemic species it contains and for the 
strong anthropic pressure it suffers. 
Such data, however, should not lead us to hasty con-
clusions. If on the one hand we have relatively solid and 
reliable numerical data on our flora, notwithstanding 
the important gaps to be filled, such as for example the 
Amazon region, on the other hand, from a qualitative 
and even quantitative point of view we still know little 
about our species. For example, data on the occurrence 
of these species in Conservation Units and their bio-
logical and/or ecological requirements are still scarce.
20 | Livro vermelho da flora do Brasil \u2013 Plantas raras do Cerrado
Referências | References
Flather, C. H. & Sieg, C. H. 2007. Species Rarity: Defi nition, 
Causes and Classifi cation. In: Raphael, M. G. & Molina, R. 
(eds.) Conservation of Rare and Little-known Species. Washington: 
Island Press.
Gaston, K.J. 1994. Rarity. Londres: Chapman and Hall.
Giulietti, A. M.; Rapini, A.; Andrade, M. J. G.; Queiroz, L. 
P. & Silva, J. M. C. (orgs.). 2009. Plantas raras do Brasil. Belo 
Horizonte: Conservação Internacional.
Lista de espécies da fl ora do Brasil. 2014. Jardim Botânico do 
Rio de Janeiro. Disponível em: <http://fl
br/>. Acesso em 11/11/2014.
Myers, N.; Mittermeier, R. A.; Fonseca, G. A. B. & Kente, J. 
2000. Biodiversity Hotspots for Conservation Priorities. 
Nature, 403:853-858.
Rabinowitz, D. 1981. Seven Forms of Rarity. In: Syngeg, H. 
(ed.). The Biological Aspects of Rare Plant Conservation. Nova York: 
Rabinowitz, D.; Cairns, S. & Dillon, T. 1986. Seven Forms of 
Rarity and Their Frequency in the Flora of the British Isles. In: 
Soulé, M. E. (ed.). Conservation Biology: the Science of Scarcity and 
Diversity. Sunderland: Sinauer Assoc.
Raphael, M. G. & Marcot, B. G. Introduction to Conservation 
of Rare or Little-known Species. In: Raphael, M. G. & 
Molina, R. (eds.). Conservation of Rare and Little-known Species. 
Washington: Island Press.
Scotland, R. W. & Wortley, A. H. 2003. How Many Species of 
Seed Plants Are There? Taxon, 52:101-104.
Wilcove, D. S.; Rothstein, D.; Dubow, J.; Philips, A. & Losos, 
E. 2000. Leading Threats to Biodiversity: What\u2019s Imperiling 
U.S. Species. In: Stein, B. A.; Kutner, L. S. & Adams, J. S. (eds.). 
Precious Heritage: the Status of Biodiversity in the United States. 
New York: