Guns, germs, and trees determine density and distribution of gorillas and chimpanzees in Western Equatorial Africa

Strindberg, Samantha; Maisels, Fiona; Williamson, Elizabeth A.; Blake, Stephen; Stokes, Emma J.; Aba’a, Rostand; Abitsi, Gaspard; Agbor, Anthony; Ambahe, Ruffin D.; Bakabana, Parfait C.; Bechem, Martha; Berlemont, Antoine; Semboli, Bruno Bokoto de; Boundja, Patrick; Bout, Nicolas; Breuer, Thomas; Campbell, Geneviève; Wachter, Pauwel De; Akou, Marc Ella; Esono, Fidel; Feistner, Anna T. C.; Fosso, Bruno; Fotso, Roger; Greer, David; Inkamba-Nkulu, Clement; Iyenguet, Calixte F.; Jeffery, Kathryn J.; Kokangoye, Max; Kühl, Hjalmar S.; Latour, Stephanie; Madzoké, Bola; Makoumbou, Calixte; Malanda, Guy-Aimé F.; Malonga, Richard; Mbolo, Victor; Morgan, David; Motsaba, Prosper; Moukala, Gabin; Mowawa, Brice S.; Murai, Mizuki; Ndzai, Christian; Nishihara, Taishi; Nzooh, Zacharie; Pintea, Lilian; Pokempner, Amy; Rainey, Hugo; Rayden, Tim; Ruffler, Heidi; Sanz, Crickette; Todd, Angelique; Vanleeuwe, Hilde; Vosper, Ashley; Warren, Ymke; Wilkie, David

doi:10.1126/sciadv.aar2964

Cited by 90 publications

(144 citation statements)

References 44 publications

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“…These results affirm the diversity and distinctiveness in modeled P. t. ellioti habitats in Cameroon (Sesink Clee et al, ). Rainforests are often presumed to be the “ideal” chimpanzee habitat, with most ENM studies positing that intact forests are necessary for chimpanzee survival, and that ecotones and anthropogenically modified sites are not suitable for sustaining large, healthy populations (Sesink Clee et al, ; Strindberg et al, ). Our results however show that these “marginal” habitats have the resources to sustain large chimpanzee populations, a fact that would be lost with large scale habitat suitability models.…”

Section: Discussionmentioning

confidence: 99%

“…Ecological niche models (ENMs) are widely used to characterize habitat suitability for a species in a given location, and information from these models may be used to predict the species distribution patterns, densities, and trends (Junker et al, ; Sesink Clee et al, ). Several recent ENM studies estimate suitable habitats of apes using known ape distributions (Junker et al, ; Sesink Clee et al, ; Strindberg et al, ) and project ape population decline due to anthropogenic pressures and infectious disease risk, most notably resulting from Ebola; and climate change (Sesink Clee et al, ; Strindberg et al, ; Walsh et al, ). These studies rely upon global environmental datasets that describe several abiotic and biotic factors, such as tree cover, surface moisture, precipitation, and seasonality, generally sampled at 1‐km 2 resolution (Dimiceli et al, ; Farr et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Habitat differentiation among three Nigeria–Cameroon chimpanzee (Pan troglodytes ellioti) populations

Abwe

Morgan

Tchiengué

et al. 2019

Ecology and Evolution

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Ecological niche models (ENMs) are often used to predict species distribution patterns from datasets that describe abiotic and biotic factors at coarse spatial scales. Ground‐truthing ENMs provide important information about how these factors relate to species‐specific requirements at a scale that is biologically relevant for the species. Chimpanzees are territorial and have a predominantly frugivorous diet. The spatial and temporal variation in fruit availability for different chimpanzee populations is thus crucial, but rarely depicted in ENMs. The genetic and geographic distinction within Nigeria–Cameroon chimpanzee (Pan troglodytes ellioti) populations represents a unique opportunity to understand fine scale species‐relevant ecological variation in relation to ENMs. In Cameroon, P. t. ellioti is composed of two genetically distinct populations that occupy different niches: rainforests in western Cameroon and forest–woodland–savanna mosaic (ecotone) in central Cameroon. We investigated habitat variation at three representative sites using chimpanzee‐relevant environmental variables, including fruit availability, to assess how these variables distinguish these niches from one another. Contrary to the assumption of most ENM studies that intact forest is essential for the survival of chimpanzees, we hypothesized that the ecotone and human‐modified habitats in Cameroon have sufficient resources to sustain large chimpanzee populations. Rainfall, and the diversity, density, and size of trees were higher at the rainforest. The ecotone had a higher density of terrestrial herbs and lianas. Fruit availability was higher at Ganga (ecotone) than at Bekob and Njuma. Seasonal variation in fruit availability was highest at Ganga, and periods of fruit scarcity were longer than at the rainforest sites. Introduced and secondary forest species linked with anthropogenic modification were common at Bekob, which reduced seasonality in fruit availability. Our findings highlight the value of incorporating fine scale species‐relevant ecological data to create more realistic models, which have implications for local conservation planning efforts.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Habitat differentiation among three Nigeria–Cameroon chimpanzee (Pan troglodytes ellioti) populations

Abwe

Morgan

Tchiengué

et al. 2019

Ecology and Evolution

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“…85,86 Western gorillas are much more abundant and occupy a larger range than eastern gorillas (approximately 656,000 km 2 ), but their numbers are expected to decline rapidly. 181,184 Ebola has decimated some populations of western gorillas and poses a large risk for a rapid decline of western gorillas. 174,185 While only a few hundred tourists view habituated western gorillas each year, the risk of disease transmission is still present.…”

Section: Gorillas and Human Evolutionmentioning

confidence: 99%

Variation in the social organization of gorillas: Life history and socioecological perspectives

Robbins

2018

Evolutionary Anthropology

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A focus of socioecological research is to understand how ecological, social, and life history factors influence the variability of social organization within and between species. The genus Gorilla exhibits variability in social organization with western gorilla groups being almost exclusively one‐male, yet approximately 40% of mountain gorilla groups are multimale. We review five ultimate causes for the variability in social organization within and among gorilla populations: human disturbance, ecological constraints on group size, risk of infanticide, life history patterns, and population density. We find the most evidence for the ecological constraints and life history hypotheses, but an over‐riding explanation remains elusive. The variability may hinge on variation in female dispersal patterns, as females seek a group of optimal size and with a good protector male. Our review illustrates the challenges of understanding why the social organization of closely related species may deviate from predictions based on socioecological and life history theory.

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“…species richness and abundance) (Kamdem-Toham et al, 2003;Gibson et al, 2011). However, increasing human pressure for resources, such as bushmeat and timber, cause major losses in biodiversity which threaten the ecological functioning of tropical rainforests (Fa, Peres & Meeuwig, 2002;Cardinale et al, 2006;Laurance et al, 2006;Gibson et al, 2011;Strindberg et al, 2018). For example, many plants depend on animal agents for seed dispersal and a reduction in these animal species can cause a disrupted seed dispersal cycle, and thus altered ecosystem functioning (Wang et al, 2007;Campos-Arceiz & Blake, 2011;Petre et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Drivers affecting mammal community structure and functional diversity under varied conservation efforts in a tropical rainforest in Cameroon

Laméris

Tagg

Kuenbou

et al. 2019

Animal Conservation

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As well as leading to a loss of biodiversity (i.e. species richness and abundance), human activities also affect ecosystem functioning. Documenting how the suite of ecological roles changes following disturbance provides a complementary source of information for conservation management. To this end, we measured mammal diversity in terms of community structure (i.e. abundance, composition and species richness) and functional diversity in three sites differing in conservation effort in a tropical rainforest in Cameroon. Results show that sites without primary or secondary conservation efforts had lower mammal abundances and an altered mammal composition but similar species richness compared to better‐protected areas. In terms of functional diversity, we found more variation of traits (i.e. FDis) in the site with primary conservation and higher abundances of functionally unique species (i.e. FOri) in sites with either primary or secondary conservation efforts. We found no overall difference in the abundance of specialist and generalist species between sites (i.e. FSpe). We identified several drivers affecting abundance, species richness and functional diversity of mammal communities, although there did not appear to be a common driver affecting all mammal diversity measures in a similar way. Our results suggest that, in addition to preserving mammal abundance and community composition, conservation efforts (both primary and secondary) are able to contribute to maintaining higher levels of functional diversity compared to areas devoid of conservation. We demonstrate that functional diversity metrics can provide valuable additional information about the status of mammal communities that can be used to better inform conservation management.

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Guns, germs, and trees determine density and distribution of gorillas and chimpanzees in Western Equatorial Africa

Abstract: We quantify the impacts of poaching, Ebola, and habitat degradation on western lowland gorillas and central chimpanzees.

Cited by 90 publications

References 44 publications

Habitat differentiation among three Nigeria–Cameroon chimpanzee (Pan troglodytes ellioti) populations

Habitat differentiation among three Nigeria–Cameroon chimpanzee (Pan troglodytes ellioti) populations

Variation in the social organization of gorillas: Life history and socioecological perspectives

Drivers affecting mammal community structure and functional diversity under varied conservation efforts in a tropical rainforest in Cameroon

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