Predicting range shifts of African apes under global change scenarios
Authors: Carvalho Joana S. , Graham Bruce , Bocksberger Gaёlle , Maisels Fiona , Williamson Elizabeth A. , Wich Serge , Sop Tenekwetche , Amarasekaran Bala , Bergl Richard A. , Boesch Christophe , Boesch Hedwige , Brncic Terry M. , Buys Bartelijntje , Chancellor Rebecca , Danquah Emmanuel , Doumbé Osiris A. , Galat-Luong Anh , Ganas Jessica , Gatti Sylvain , Ghiurghi Andrea , Goedmakers Annemarie , Granier Nicolas , Hakizimana Dismas , Haurez Barbara , Head Josephine , Herbinger Ilka , Hillers Annika , Jones Sorrel , Manasseh Eno-Nku , McCarthy Maureen S. , Morgan Bethan J. , Nixon Stuart , Nkembi Louis , Normand Emmanuelle , Olson Sarah H. , Payne Leon , Petre Charles-Albert , Piel Alex K. , Pintea Lilian , Plumptre Andrew J. , Rundus Aaron , Serckx Adeline , Stewart Fiona A. , Sunderland-Groves Jacqueline , Tagg Nikki , Todd Angelique , Vosper Ashley , Wenceslau José Francisco Carminatti , Wessling Erin G. , Willie Jacob , Kühl Hjalmar 
Published: June 2020

Aim

Modelling African great ape distribution has until now focused on current or past conditions, whilst future scenarios remain scarcely explored. Using an ensemble forecasting approach, we predicted changes in taxon-specific distribution under future scenarios of climate, land-use and human population changes.

Location

Sub-Saharan Africa

Methods

We compiled occurrence data on African ape populations from the IUCN A.P.E.S. database and extracted relevant human-, climate- and habitat-related predictors representing current and future (2050) conditions to predict taxon-specific distribution under a best- and a worst-case scenario, using ensemble forecasting. Given the large effect on model predictions, we further tested algorithm sensitivity by consideringdefaultandnon-defaultmodelling options. The latter included interactions between predictors and polynomial terms in correlative algorithms.

Results

The future distributions of gorilla and bonobo populations are likely to be directly determined by climate-related variables. In contrast, future chimpanzee distribution is influenced mostly by anthropogenic variables. Both our modelling approaches produced similar model accuracy, although a slight difference in the magnitude of range change was found forGorilla beringei beringei, G. gorilla diehli, andPan troglodytes schweinfurthii. On average, a decline of 50% of the geographic range (non-default; or 55%default) is expected under the best scenario if no dispersal occurs (57%non-defaultor 58%defaultin worst scenario). However, new areas of suitable habitat are predicted to become available for most taxa if dispersal occurs (81% or 103% best, 93% or 91% worst,non-defaultanddefault, respectively), except forG. b. beringei.

Main Conclusions

Despite the uncertainty in predicting the precise proportion of suitable habitat by 2050, both modelling approaches predict large range losses for all African apes. Thus, conservation planners urgently need to integrate land-use planning and simultaneously support conservation and climate change mitigation measures at all decision-making levels both in range countries and abroad.