Quantitative estimates of glacial refugia for chimpanzees (Pan troglodytes) since the Last Interglacial (120,000 BP)

Citation

Barratt CD, Lester JD, Gratton P, Onstein RE, Kalan AK, McCarthy MS, Bocksberger G, White LC, Vigilant L, Dieguez P, Abdulai B, Aebischer T, Agbor A, Maisels F & Morgan B (2021) Quantitative estimates of glacial refugia for chimpanzees (Pan troglodytes) since the Last Interglacial (120,000 BP). American Journal of Primatology, 83 (10), Art. No.: e23320. https://doi.org/10.1002/ajp.23320

Abstract
Paleoclimate reconstructions have enhanced our understanding of how past climates have shaped present-day biodiversity. We hypothesize that the geographic extent of Pleistocene forest refugia and suitable habitat fluctuated significantly in time during the late Quaternary for chimpanzees (Pan troglodytes). Using bioclimatic variables representing monthly temperature and precipitation estimates, past human population density data, and an extensive database of georeferenced presence points, we built a model of changing habitat suitability for chimpanzees at fine spatio-temporal scales dating back to the Last Interglacial (120,000 BP). Our models cover a spatial resolution of 0.0467° (approximately 5.19 km2 grid cells) and a temporal resolution of between 1000 and 4000 years. Using our model, we mapped habitat stability over time using three approaches, comparing our modeled stability estimates to existing knowledge of Afrotropical refugia, as well as contemporary patterns of major keystone tropical food resources used by chimpanzees, figs (Moraceae), and palms (Arecacae). Results show habitat stability congruent with known glacial refugia across Africa, suggesting their extents may have been underestimated for chimpanzees, with potentially up to approximately 60,000 km2 of previously unrecognized glacial refugia. The refugia we highlight coincide with higher species richness for figs and palms. Our results provide spatio-temporally explicit insights into the role of refugia across the chimpanzee range, forming the empirical foundation for developing and testing hypotheses about behavioral, ecological, and genetic diversity with additional data. This methodology can be applied to other species and geographic areas when sufficient data are available.

Keywords
Africa; diversification; ensemble; paleoclimate; species distribution modeling

Notes
Additional co-authors: Alfred K. Assumang, Emma Bailey, Mattia Bessone, Bartelijntje Buys, Joana S. Carvalho, Rebecca Chancellor, Heather Cohen, Emmanuel Danquah, Tobias Deschner, Zacharie N. Dongmo, Osiris A. Doumbé, Jef Dupain, Chris S. Duvall, Manasseh Eno-Nku, Gilles Etoga, Anh Galat-Luong, Rosa Garriga, Sylvain Gatti, Andrea Ghiurghi, Annemarie Goedmakers, Anne-Céline Granjon, Dismas Hakizimana, Josephine Head, Daniela Hedwig, Ilka Herbinger, Veerle Hermans, Sorrel Jones, Jessica Junker, Parag Kadam, Mohamed Kambi, Ivonne Kienast, Célestin Y. Kouakou, Kouamé P. N′Goran, Kevin E. Langergraber, Juan Lapuente, Anne Laudisoit, Kevin C. Lee, Nadia Mirghani, Deborah Moore, David Morgan, Emily Neil, Sonia Nicholl, Louis Nkembi, Anne Ntongho, Christopher Orbell, Lucy Jayne Ormsby, Liliana Pacheco, Alex K. Piel, Lilian Pintea, Andrew J. Plumptre, Aaron Rundus, Crickette Sanz, Volker Sommer, Tenekwetche Sop, Fiona A. Stewart, Jacqueline Sunderland-Groves, Nikki Tagg, Angelique Todd, Els Ton, Joost van Schijndel, Hilde VanLeeuwe, Elleni Vendras, Adam Welsh, José F. C. Wenceslau, Erin G. Wessling, Jacob Willie, Roman M. Wittig, Nakashima Yoshihiro, Yisa Ginath Yuh, Kyle Yurkiw, Christophe Boesch, Mimi Arandjelovic, Hjalmar Kühl

Journal
American Journal of Primatology: Volume 83, Issue 10

• Published version