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Thompson, J.J.; Velilla, M.
Modeling the effects of deforestation on the connectivity of jaguar_ Panthera onca _populations at the southern extent of the species' range
2017  Endangered Species Research (34): 109-121

We employed least-cost and circuit theory modeling to model connectivity among previously defined Jaguar Conservation Units (JCUs) at the southern limit of the jaguar's range in Argentina, Bolivia, Brazil and Paraguay, to assess the effects of deforestation and land use change from 2000 to 2014. Due to uncertainty over possible limitations to jaguar dispersal, we examined connectivity where linkages were not cost-limited and limited to 1000 km cost-weighted distance. When linkage length was not cost-limited, total linkage area decreased by 9%, mean least-cost distance and mean effective resistance increased by 6% and 31%, respectively, from 2000 to 2014. Limiting linkages to 1000 km cost-weighted distance indicated that the southern- and eastern-most JCUs were isolated as early as 2000 and that the number of linkages between the other JCUs decreased during 2000-2014, causing the linkage area to decrease by 27%, while the least-cost distance of the remaining linkages increased by a mean of 4% and effective resistance increased on average by 44%. By limiting linkages to a plausible cost-weighted distance, we demonstrated that JCUs in the Atlantic Forest, Argentine Chaco and the Argentine/Bolivian Yungas have been isolated since at least 2000, a loss of connectivity through eastern Bolivia, increased resistance in the remaining linkages and a constriction of all but one linkage to a minimum width of <8 km. Our results are consistent with an observed loss of genetic diversity in jaguar populations within portions of our study area and indicate a need for further research to better quantify jaguar dispersal.

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