New, multidimensional primate niches provide insights into the role of competition in primate lives and evolution

wild chimpanzee 'Kaija' from the Nimba Mountains, Guinea, West Africa

Wild chimpanzee 'Kaija' from the Nimba Mountains, Guinea, West Africa | Image: Dr Laura van Holstein

Wild chimpanzee 'Kaija' from the Nimba Mountains, Guinea, West Africa | Image: Dr Laura van Holstein

A team of researchers at the University of Cambridge and University of Zurich calculated niches of 191 primate species in a seven-dimensional space. They used this to show how primate niches evolved and calculate which groups of primates experience the highest levels of between-species competition.

Prof. Kathelijne Koops and Dr Laura Von Holstein in the Nimba Mountains, Guinea, West Africa

Prof. Kathelijne Koops and Dr Laura Von Holstein in the Nimba Mountains, Guinea, West Africa | Image: Prof. Kathelijne Koops

Prof. Kathelijne Koops and Dr Laura Von Holstein in the Nimba Mountains, Guinea, West Africa | Image: Prof. Kathelijne Koops

Niches are a notoriously widely used, but ill-defined, concept in evolutionary biology. There are multiple definitions, spanning from ‘the resources an animal needs to survive’ to ‘what an animal does in its environment’ to ‘the location in which a species can continue to increase in numbers’. Many definitions, paired with difficulties in going from abstract definition to measured variable, has made it historically difficult to ‘measure’ niches for groups of animals.

In the study, published in Nature Communications Biology, researchers have provided a new way to calculate primate niches. They collected data on 11 traits (including average body size, life history, diet, habitat breadth, and climate) for 191 primate species, and calculated where species fit within a seven-dimensional space made up of these variables.

“Taking into account these different types of variables in a single analysis means we essentially combined all definitions of niches”, Laura van Holstein, joint lead author of the paper, said. “From this, we showed, first of all, that Asian and African monkeys, and great apes, are the most diverse groups when all of these variables are taken together. You might not have expected this, because, for example, if you only look at one variable – body size – great apes aren’t that diverse: they are all fairly large for primates. But when you consider all variables, great apes are much more diverse than, say, South American monkeys”.

The team then ran phylogenetic comparative analyses to ask how primate niches change over evolutionary time. They show that, instead of traits evolving independently, primate evolution happened through natural selection for optimal combinations of traits. “This is interesting because many studies focus only on the evolution of a single trait,” said van Holstein, “but this is not necessarily the way evolution works.”

The team then used the seven-dimensional space to calculate which species undergo the most between-species competition, and which species the least. “Species cannot live in the same place and occupy the exact same niche,” van Holstein explained. “This between-species competition is an important driver of evolution: if species compete intensely, then the outcome is either one evolves a different combination of traits to occupy a different niche, or it goes extinct.”

Fig.2 from the paper - showing the first 3 dimensions of the 7-dimensional niche space

Fig.2 from the paper - showing the first 3 dimensions of the 7-dimensional niche space

Fig.2 from the paper - showing the first 3 dimensions of the 7-dimensional niche space

Two different species living together | Image: Jonas Abana Eriksson

Two different species living together | Image: Jonas Abana Eriksson

Dr Laura van Holstein

Dr Laura van Holstein | Image: Dr Laura van Holstein

Dr Laura van Holstein | Image: Dr Laura van Holstein

Species that are closer to each other in the seven-dimensional niche space, the authors reasoned, therefore likely experience more competition. They found that South American tamarins and marmosets experience high levels of competition. “This is a surprising and intriguing result,” according to van Holstein, “because we know that these species often associate with each other in big mixed-species groups in the wild. So how are they dealing with the negative evolutionary consequences of competition that great apes have managed to escape?”

In contrast, great apes experience low levels of competition from other primates. “Great apes have clearly found a unique niche space compared to other primates: they are the least primate-y primates. This means they avoid the negative evolutionary consequences of between-species competition,” explained van Holstein.

These results have implications beyond evolutionary biology, according to the authors. Van Holstein: “Niches describe what an animal is doing in an environment: its role and what it needs. Ecosystem stability depends on niches being filled. Going forward, we can use our seven-dimensional space to understand which species will represent the biggest losses in terms of niche uniqueness: the species that, if they were to go extinct, would cause an above-average loss of unique ecosystem functions. This may help in conservation prioritization.”

The paper is published here in Nature Communications Biology.

Funded by a Clare College Junior Research Fellowship (2022-25) awarded to Dr Laura van Holstein.

The team:

  • Dr Laura van Holstein is a Junior Research Fellow at Clare College and works on interspecific competition in human and primate evolution. She has been at Cambridge and the Department of Archaeology since 2013 both as an Undergraduate and PhD student.
  • Hannah McKay completed an MPhil in Human Evolutionary Studies in the Department of Archaeology in 2021-22; some work in this paper is based on her Master's dissertation.
  • Prof. Kathelijne Koops was Lecturer in Primatology until 2020; now Professor at the University of Zurich. She works on great ape behaviour. 
  • Prof. Catalina Pimiento is a Professor at the University of Zurich, and she mainly works on shark & other marine functional trait evolution. 

Published 29 May 2024

The text in this work is licensed under a Creative Commons Attribution 4.0 International License