Walker’s Manihot (Manihot walkerae) is a federally endangered plant species that is endemic to the Tamaulipan thornscrub ecoregion. Known M. walkerae populations are found in South Texas and northeastern Tamaulipas, Mexico, and are highly fragmented with most being found on protected lands or private property. The most detrimental existing threats for M. walkerae are habitat loss and competition from invasive species, but the effect that climate change could have on M. walkerae’s suitable habitat remains unexplored and could result in further restriction. Our objective was to use the maximum entropy algorithm (MaxEnt) to predict how climate change could affect M. walkerae’s suitable habitat. We visualized the current and future potential suitable habitat for M. walkerae for the years 2050 and 2070 using three different general circulation models CM3, CMIP5, and HADGEM, and two climate change scenarios RCP 4.5 and 8.5. Nineteen bioclimatic variables representative of each scenario were acquired from the WorldClim database and highly correlated variables were removed leaving only ten bioclimatic variables for modeling. Nineteen spatially rarefied occurrences for M. walkerae and ten bioclimatic variables were in put to MaxEnt to produce twenty replicates for each case and geographic information systems was used to construct the consensus models.
Results/Conclusions
The area under the curve (AUC) values of the consensus models were higher than 0.90, indicating that the models had a high predictive ability. The projected effect of climate change on the potential suitable habitat for M. walkerae was variable throughout the models, but collectively they predict a loss of suitable potential habitat. The most severe predicted loss of habitat was with the CMIP5 general circulation model at an RCP of 4.5 for the year 2070, with a 14 % reduction of suitable habitat. As for the year 2050, the most significant loss was over 9% for the CM3 general circulation model at an RCP of 8.5. The results of this project show that climate change could play an additional role in the future loss of potential suitable habitat for the endangered species M. walkerae. Additionally, it is important to consider how climate change could synergistically act with other detrimental factors already affecting this species such as modification of suitable habitat. Bringing awareness to the potential effect of climate change on M. walkerae’s suitable habitat is essential and must be considered when developing conservation plans for this species, and for other vulnerable endemic plant species of this ecoregion.