Trends and Developments in Biodiversity Informatics
Flora brasiliensis Revisited
Modeling Species Ecological Niches with GARP - a example of
predicting the potential of invasion of two Crotalaria species
(Fabaceae) in Conservation Units in Brazil
Rafael Luís Fonseca(CRIA),
Paulo Roberto Guimarães Jr. (UNICAMP),
Sérgio Rodrigues Morbiolo (UNICAMP),
Ricardo Scachetti Pereira (CRIA),
Andrew Townsend Peterson (U. Kansas)
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GARP is a genetic algorithm that creates ecological niche models for
species. The models describe environmental conditions under which the
species should be able to maintain populations. For input, GARP uses a
set of point localities where the species is known to occur and a set of
geographic layers representing the environmental parameters that might
limit the species' capabilities to survive. GARP searches iteratively
for non-random correlations between species presence and absence and
environmental parameter values using several different types of rules.
Each rule type implements a different method for building species
prediction models. Currently there are four types of rules implemented:
atomic, logistic regression, bioclimatic envelope, and negated
bioclimatic envelope rules. Like an example for how GARP works, we
investigated the potential of invasiveness of two pantropical weeds
(Crotalaria pallida Ait. and Crotalaria incana L.) in conservation
units. We used the records of these two species in Africa (probable
natural occurrence) to model the ecological niche and applied the
modeled ecological niche to South America. The models for native
(Africa) and exotic (South America) distribution for both species made
good prediction to occurrence points in these areas (P < 0.001,
randomization test). The highest probability of occurrence of C.
pallida
encloses all but a few large parks of Brazil (binomial test; P < 0.05),
including the recent created world's largest biological reserve. Both
species are more like to occur in openlands (Cerrado, Pantanal) and high
fragmented areas (Atlantic Forest) than forests (Amazon). Although C.
incana is also widespread, it is often more unlikely to occurs than C.
pallida in near all parks (binomial test; P < 0.05). The openlands
occurrence is a widespread feature of Crotalaria genus, and the highest
probability of infestation by C. pallida may be related to its more
widespread African distribution than C. incana.
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