Research Background
The Anthropocene extinction threatens to make all non-human great ape species extinct in the wild by the end of the century \cite{Carvalho_2021}. Great apes are particularly vulnerable to Anthropogenic threats due to their slow life history, long inter-birth intervals, and low population densities \cite{Purvis2000}. Habitat destruction, climate change, pollution and the synergistic effects between all of these have already enormously reduced great ape ranges worldwide, and the impacts are predicted to worsen for all great ape species over time \cite{Carvalho_2021,Purvis2000,Junker_2012,K_hl_2019} .
While in the 20th century land use change was the largest driver of great ape extinction, by 2070 climate change is predicted to become the largest driver of extinction in great ape populations, due to existing habitat fragmentation, and poor thermoregulation limiting dispersal abilities \cite{Junker_2012}. Under current emissions, Carvlho et al. predict a 94 percent loss of great ape habitat in Africa by 2050. Even under RCP 2.6, a 85% decrease in great ape range sizes is predicted in just 3 decades time. These enormous reductions are due to human population changes, which land use change in existing ranges and future potential areas (outside of protected areas), and climate change, which impacts the viability of existing ranges and increases human demand for existing land currently containing great ape populations \cite{Carvalho_2021}.
Climate change, of course, does not just affect wild animals. Climate change has dramatic impact on water availability, soil viability, disease emergence and phenological mismatch - all of which causes human mass migration, increases illegal logging, hunting and demand for bush meat \cite{Ordaz_N_meth_2017,Junker_2012,Brodie_2009,Virah_Sawmy_2010}. As the century goes on humanity itself will become synergistic stressor to the all of the factors affecting range size in great apes worldwide \cite{Carvalho_2021}.
As the total land suitable for great ape habitation becomes smaller due to the above factors, the ecological constraints model predicts existing populations will be forced into competition over limited resources and increasingly come into contact with other groups - especially as decreased productivity of the land increases the required range size needed to support the same population size \cite{Struebig_2015,Junker_2012}.
On a species level, the effect of global change on great ape populations is well described, and on an individual level the impacts of reduced water availability and habitat on fitness is understood \cite{Carvalho_2021,Purvis2000,Junker_2012}. What is less understood currently is the impact these changes will have on communities, and the relationships between them.