17 Works

Data from: A stoichiometric perspective of the effect of herbivore dung on ecosystem functioning

Judith Sitters & Harry Olde Venterink
Ungulate herbivores play a prominent role in maintaining the tree–grass balance in African savannas. Their top-down role through selective feeding on either trees or grasses is well studied, but their bottom-up role through deposition of nutrients in dung and urine has been overlooked. Here, we propose a novel concept of savanna ecosystem functioning in which the balance between trees and grasses is maintained through stoichiometric differences in dung of herbivores that feed on them. We...

Data from: Large wildlife removal drives immune defense increases in rodents

Hillary S. Young, Rodolfo Dirzo, Kristofer M. Helgen, Douglas J. McCauley, Charles L. Nunn, Paul Snyder, Kari E. Veblen, Serena Zhao & Vanessa O. Ezenwa
Anthropogenic disturbances involving land use change, climate disruption, pollution, and invasive species have been shown to impact immune function of wild animals. These immune changes have direct impacts on the fitness of impacted animals and, also, potentially indirect effects on other species and on ecological processes, notably involving the spread of infectious disease. Here, we investigate whether the selective loss of large wildlife can also drive changes in immune function of other consumer species. Using...

Data from: Climatic variation modulates the indirect effects of large herbivores on small-mammal habitat use

Ryan A. Long, Alois Wambua, Jacob R. Goheen, Todd M. Palmer & Robert M. Pringle
Large mammalian herbivores (LMH) strongly shape the composition and architecture of plant communities. A growing literature shows that negative direct effects of LMH on vegetation frequently propagate to suppress the abundance of smaller consumers. Indirect effects of LMH on the behaviour of these consumers, however, have received comparatively little attention despite their potential ecological significance. We sought to understand (i) how LMH indirectly shape small-mammal habitat use by altering the density and distribution of understorey...

Data from: Polygyny does not explain the superior competitive ability of dominant ant associates in the African ant-plant, Acacia (Vachellia) drepanolobium

John H. Boyle, Dino J. Martins, Julianne Pelaez, Paul M. Musili, Staline Kibet, S. Kimani Ndung'u, David Kenfack & Naomi E. Pierce
1. The Acacia drepanolobium (also known as Vachellia drepanolobium) ant-plant symbiosis is considered a classic case of species coexistence, in which four species of tree-defending ants compete for nesting space in a single host tree species. Coexistence in this system has been explained by trade-offs in the ability of the ant associates to compete with each other for occupied trees versus the ability to colonize unoccupied trees. 2. We seek to understand the proximal reasons...

Data from: Synergistic effects of fire and elephants on arboreal animals in an African savannah

Robert M. Pringle, Duncan M. Kimuyu, Ryan L. Sensenig, Todd M. Palmer, Corinna Riginos, Kari E. Veblen & Truman P. Young
1. Disturbance is a crucial determinant of animal abundance, distribution and community structure in many ecosystems, but the ways in which multiple disturbance types interact remain poorly understood. The effects of multiple-disturbance interactions can be additive, subadditive or super-additive (synergistic). Synergistic effects in particular can accelerate ecological change; thus, characterizing such synergies, the conditions under which they arise, and how long they persist has been identified as a major goal of ecology. 2. We factorially...

Data from: Interacting effects of wildlife loss and climate on ticks and tick-borne disease

Georgia Titcomb, Brian F. Allan, Tyler Ainsworth, Henson Lauren, Tyler Hedlund, Robert M. Pringle, Todd M. Palmer, Laban Njoroge, Michael G. Campana, Robert C. Fleischer, John Naisikie Mantas, Hillary S. Young & Lauren Henson
Both large-wildlife loss and climatic changes can independently influence the prevalence and distribution of zoonotic disease. Given growing evidence that wildlife loss often has stronger community-level effects in low-productivity areas, we hypothesized that these perturbations would have interactive effects on disease risk. We experimentally tested this hypothesis by measuring tick abundance and the prevalence of tick-borne pathogens (Coxiella burnetii and Rickettsia spp.) within long-term, size-selective, large-herbivore exclosures replicated across a precipitation gradient in East Africa....

Wild herbivores enhance resistance to invasion by exotic cacti in an African savanna

Harry Wells, Ramiro Crego, Jesse Alston, S. Kimani Ndung'u, Leo Khasoha, Courtney Reed, Abdikadir Hassan, Samson Kurukura, Jackson Ekadeli, Mathew Namoni, Peter Stewart, Duncan Kimuyu, Amelia Wolf, Truman Young, Tyler Kartzinel, Todd Palmer, Jacob Goheen & Robert Pringle
1. Whether wild herbivores confer biotic resistance to invasion by exotic plants remains a key question in ecology. There is evidence that wild herbivores can impede invasion by exotic plants, but it is unclear whether and how this generalises across ecosystems with varying wild herbivore diversity and functional groups of plants, particularly over long-term (decadal) time frames. 2. Using data from three long-term (13- to 26-year) exclosure experiments in central Kenya, we tested the effects...

Data from: Context-dependent effects of large wildlife declines on small mammal communities in central Kenya

Hillary S. Young, Douglas J. McCauley, Rodolfo Dirzo, Jacob R. Goheen, Bernard Agwanda, Cara Brook, Erik O. Castillo, Adam W. Ferguson, Stephen N. Kinyua, Molly M. McDonough, Todd M. Palmer, Robert M. Pringle, Truman P. Young & Kristofer M. Helgen
Many species of large wildlife have declined drastically worldwide. These reductions often lead to profound shifts in the ecology of entire communities and ecosystems. However, the effects of these large wildlife declines on other taxa likely hinge upon both underlying abiotic properties of these systems and on the types of secondary anthropogenic changes associated with wildlife loss, making impacts difficult to predict. To better understand how these important contextual factors determine the consequences of large-wildlife...

Data from: Similar but different: dynamic social network analysis highlights fundamental differences between the fission-fusion societies of two equid species, the onager and Grevy's zebra

Daniel I. Rubenstein, Siva R. Sundaresan, Ilya R. Fischhoff, Chayant Tantipathananandh & Tanya Y. Berger-Wolf
Understanding why animal societies take on the form that they do has benefited from insights gained by applying social network analysis to patterns of individual associations. Such analyses typically aggregate data over long time periods even though most selective forces that shape sociality have strong temporal elements. By explicitly incorporating the temporal signal in social interaction data we re-examine the network dynamics of the social systems of the evolutionarily closely-related Grevy’s zebras and wild asses...

Data from: Whole-chromosome hitchhiking driven by a male-killing endosymbiont

Simon Martin, Kumar Singh, Ian Gordon, Kennedy Omufwoko, Steve Collins, Ian Warren, Hannah Munby, Oskar Brattström, Walther Traut, Dino Martins, David Smith, Chris Jiggins, Chris Bass & Richard French-Constant
Neo-sex chromosomes are found in many taxa, but the forces driving their emergence and spread are poorly understood. The female-specific neo-W chromosome of the African monarch (or queen) butterfly Danaus chrysippus presents an intriguing case study because it is restricted to a single ‘contact zone’ population, involves a putative colour patterning supergene, and co-occurs with infection by the the male-killing endosymbiont Spiroplasma. We investigated the origin and evolution of this system using whole genome sequencing....

Data from: Economy of scale: third partner strengthens a keystone ant-plant mutualism

Kirsten M. Prior & Todd M. Palmer
While foundation species can stabilize ecosystems at landscape scales, their ability to persist is often underlain by keystone interactions occurring at smaller scales. Acacia drepanolobium is a foundation tree, comprising >95% of woody cover in East African black-cotton savanna ecosystems. Its dominance is underlain by a keystone mutualistic interaction with several symbiotic ant species in which it provides housing (swollen thorns) and carbohydrate-rich nectar from extra-floral nectaries (EFN). In return, it gains protection from catastrophic...

Data from: Population genomics and demographic sampling of the ant-plant Vachellia drepanolobium and its symbiotic ants from sites across its range in East Africa.

John H. Boyle, Dino Martins, Paul M. Musili & Naomi E. Pierce
The association between the African ant plant, Vachellia drepanolobium, and the ants that inhabit it has provided insight into the boundaries between mutualism and parasitism, the response of symbioses to environmental perturbations, and the ecology of species coexistence. We use a landscape genomics approach at sites sampled throughout the range of this system in Kenya to investigate the demographics and genetic structure of the different partners in the association. We find that different species of...

Data from: Termite mounds can increase the robustness of dryland ecosystems to climatic change

Juan A. Bonachela, Robert M. Pringle, Efrat Sheffer, Tyler C. Coverdale, Jennifer A. Guyton, Kelly K. Caylor, Simon A. Levin & Corina E. Tarnita
Self-organized spatial vegetation patterning is widespread and has been described using models of scale-dependent feedback between plants and water on homogeneous substrates. As rainfall decreases, these models yield a characteristic sequence of patterns with increasingly sparse vegetation, followed by sudden collapse to desert. Thus, the final, spot-like pattern may provide early warning for such catastrophic shifts. In many arid ecosystems, however, termite nests impart substrate heterogeneity by altering soil properties, thereby enhancing plant growth. We...

Data from: Distinctive fungal communities in an obligate African ant-plant mutualism

Christopher C.M. Baker, Dino J. Martins, Julianne N. Pelaez, Johan P.J. Billen, Anne Pringle, Megan E. Frederickson, Naomi E. Pierce, Christopher C. M. Baker & Johan P. J. Billen
Three ant species nest obligately in the swollen-thorn domatia of the African ant-plant Vachellia (Acacia) drepanolobium, a model system for the study of ant-defence mutualisms and species coexistence. Here we report on the characteristic fungal communities generated by these ant species in their domatia. First, we describe behavioural differences between the ant species when presented with a cultured fungal isolate in the laboratory. Second, we use DNA metabarcoding to show that each ant species has...

Large herbivores transform plant-pollinator networks in an African savanna

Matthew C. Hutchinson, Travis J. Guy, Todd M. Palmer, Robert M. Pringle, Katherine C. R. Baldock, Elisha Kayser, Benjamin Baiser, Phillip P. A. Staniczenko, Jacob R. Goheen, Robert M. Pringle & Todd M. Palmer
Pollination by animals is a key ecosystem service1,2 and interactions between plants and their pollinators are a model system for the study of ecological networks3,4, yet plant-pollinator networks are typically studied in isolation from the broader ecosystems in which they are embedded. The plants visited by pollinators also interact with other consumer guilds that eat stems, leaves, fruits, or seeds. One such guild, large mammalian herbivores, are well-known ecosystem engineers5–7 and may have substantial impacts...

Global biogeography of warning colouration in the butterfly Danaus chrysippus

Wanzhen Liu, David A. S. Smith, Gayatri Raina, Rowan Stanforth, Ivy Ng’Iru, Piera Ireri, Dino J. Martins, Ian J. Gordon & Simon H. Martin
Warning colouration provides a textbook example of natural selection, but the frequent observation of polymorphism in aposematic species presents an evolutionary puzzle. We investigated biogeography and polymorphism of warning patterns in the widespread butterfly Danaus chrysippus using records from citizen science (n=5467), museums (n=8864), and fieldwork (n=2586). We find that polymorphism in three traits controlled by known mendelian loci is extensive. Broad allele frequency clines, hundreds of km wide, suggest a balance between long-range dispersal...

The generality of cryptic dietary niche differences in diverse large-herbivore assemblages

Robert Pringle, Johan Pansu, Matthew Hutchinson, T. Michael Anderson, Mariska Te Beest, Colleen Begg, Keith Begg, Aurelie Bonin, Lackson Chama, Simon Chamaillé-Jammes, Eric Coissac, Joris Cromsigt, Margaret Demmel, Jason Donaldson, Jennifer Guyton, Christina Hansen, Christopher Imakando, Azwad Iqbal, Davis Kalima, Graham Kerley, Samson Kurukura, Marietjie Landman, Ryan Long, Isaack Munuo, Ciara Nutter … & Tyler Kartzinel
Ecological niche differences are necessary for stable species coexistence but are often difficult to discern. Models of dietary niche differentiation in large mammalian herbivores invoke the quality, quantity, and spatiotemporal distribution of plant tissues and growth-forms but are agnostic towards food-plant species identity. Empirical support for these models is variable, suggesting that additional mechanisms of resource partitioning may be important in sustaining large-herbivore diversity in African savannas. We used DNA metabarcoding to conduct a taxonomically...

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  • Mpala Research Center and Wildlife Foundation
  • Princeton University
  • University of Florida
  • University of Wyoming
  • Harvard University
  • University of California, Santa Barbara
  • National Museums of Kenya
  • Stanford University
  • Utah State University
  • University of Edinburgh