Molecular Ecology of the Wild Mandrill (Mandrillus sphinx)
Anna Weber
Anna Weber
photograph courtesy of Vivek OS
Although primates have fascinated researchers and the public alike for generations, one species that has remained enigmatic is the mandrill (Mandrillus sphinx). Mandrills are a highly charismatic species of Cercopithecine monkey, endemic to central Africa and easily recognizable by the brightly colored faces of reproductive males. Mandrills are currently in decline due to bushmeat hunting, urbanization, and habitat loss. Despite their categorization as “Vulnerable” by the International Union for the Conservation of Nature (IUCN), the majority of research on mandrills has been conducted in semi-captive populations, and little is known about the ecology of wild groups.
Neutral and adaptive genetic diversity are important tools for understanding evolutionary history and future viability, since diversity influences a species’ ability to adapt to a changing environment. However, thus far, minimal genetic information has been available for wild mandrills. Because of the dense vegetation in their tropical forest habitat, studying wild mandrills has proven to be a challenge, and the majority of research on this species has been performed on semi-captive populations.
In collaboration with researchers in Gabon and the UK, members of the Anthony Lab conducted the first-ever genetic study of wild mandrills in their natural habitat. During summers of 2016-2019, we used a non-invasive approach to collect samples of genetic material from three distinct social groups, or “hordes,” of mandrills located in Gabon’s Lopé National Park (LNP).
First, we used demographic history modeling to test for evidence of population bottlenecks in mandrills and three other forest-associated species (blue duiker [Philantomba monticola], Peters’s duiker [Cephalophus callipygus], and western lowland gorillas [Gorilla gorilla gorilla]). Despite a severe loss of forest cover in central Africa approximately 2,500 years ago, our results suggest that none of the four species experienced major population declines.
Second, we performed next-generation sequencing of the class II major histocompatibility complex (MHC), a gene family involved in adaptive immunity. We tested for a difference in replicability between sequences generated from DNA extracted from feces and that extracted from higher quality tissue. We also formulated a new method of assigning MHC alleles to individuals using degraded samples, and we use that method to characterize the MHC genes in the focal population.
Lastly, we tested for sex-specific selection on the MHC in male and female mandrills. Male mandrills are thought to be more vulnerable to pathogens than females, which may result in stronger selective pressure on the MHC genes in males.
Our results from these three studies will contribute to our understanding of mandrill evolutionary history and conservation by providing insight on the role of demographic processes and selective pressures in shaping their past and present populations.
Weber A., Lighten K., van Osterhout C.V., Guibinga Mickala A., Ntie S., Mickala P., Lehmann D., Abernethy K.A. and Anthony N.M. (2023) What mandrills leave behind: using fecal samples to characterize the major histocompatibility complex in a threatened primate. Conservation Genetics 25: 533-549.
Guibinga Mickala A., Weber, A., Ntie S., Gahlot P., Lehmann D., Mickala P., Abernethy K.A. and Anthony N.M. (2022) Estimation of the census (Nc) and effective (Ne) population size of a wild mandrill (Mandrillus sphinx) horde in the Lopé National Park, Gabon using a non-invasive genetic approach. Conservation Genetics 23: 871-83.
Neutral and adaptive genetic diversity are important tools for understanding evolutionary history and future viability, since diversity influences a species’ ability to adapt to a changing environment. However, thus far, minimal genetic information has been available for wild mandrills. Because of the dense vegetation in their tropical forest habitat, studying wild mandrills has proven to be a challenge, and the majority of research on this species has been performed on semi-captive populations.
In collaboration with researchers in Gabon and the UK, members of the Anthony Lab conducted the first-ever genetic study of wild mandrills in their natural habitat. During summers of 2016-2019, we used a non-invasive approach to collect samples of genetic material from three distinct social groups, or “hordes,” of mandrills located in Gabon’s Lopé National Park (LNP).
First, we used demographic history modeling to test for evidence of population bottlenecks in mandrills and three other forest-associated species (blue duiker [Philantomba monticola], Peters’s duiker [Cephalophus callipygus], and western lowland gorillas [Gorilla gorilla gorilla]). Despite a severe loss of forest cover in central Africa approximately 2,500 years ago, our results suggest that none of the four species experienced major population declines.
Second, we performed next-generation sequencing of the class II major histocompatibility complex (MHC), a gene family involved in adaptive immunity. We tested for a difference in replicability between sequences generated from DNA extracted from feces and that extracted from higher quality tissue. We also formulated a new method of assigning MHC alleles to individuals using degraded samples, and we use that method to characterize the MHC genes in the focal population.
Lastly, we tested for sex-specific selection on the MHC in male and female mandrills. Male mandrills are thought to be more vulnerable to pathogens than females, which may result in stronger selective pressure on the MHC genes in males.
Our results from these three studies will contribute to our understanding of mandrill evolutionary history and conservation by providing insight on the role of demographic processes and selective pressures in shaping their past and present populations.
Weber A., Lighten K., van Osterhout C.V., Guibinga Mickala A., Ntie S., Mickala P., Lehmann D., Abernethy K.A. and Anthony N.M. (2023) What mandrills leave behind: using fecal samples to characterize the major histocompatibility complex in a threatened primate. Conservation Genetics 25: 533-549.
Guibinga Mickala A., Weber, A., Ntie S., Gahlot P., Lehmann D., Mickala P., Abernethy K.A. and Anthony N.M. (2022) Estimation of the census (Nc) and effective (Ne) population size of a wild mandrill (Mandrillus sphinx) horde in the Lopé National Park, Gabon using a non-invasive genetic approach. Conservation Genetics 23: 871-83.
photograph courtesy of David Lehmann
