variable environments
Both historical and recent variation in ecological and environmental conditions are associated with larger behavioural repertoires in wild chimpanzees

Date:
September 15, 2020
Source:
Max Planck Institute for Evolutionary Anthropology
Summary:
Scientists have investigated the influence of environmental
variability on the behavioral repertoires of 144 social groups. The
scientists found that chimpanzees living further away from
historical forest refugia, under more seasonal conditions, and
found in savannah woodland rather than closed forested habitats,
were more likely to exhibit a larger set of behaviors.



FULL STORY ========================================================================== Behavioural flexibility enables species to adapt to uncertainty and
changing ecological conditions via mechanisms such as innovation and
greater cognitive capacity. Indeed, large brained species of birds or
nonhuman primates often live in habitats that are highly seasonal and can sustain periodic resource shortages. Similarly, our own species is thought
to have evolved an unprecedented level of behavioural flexibility in
order to adapt and survive in fluctuating and unpredictable environmental conditions.


==========================================================================
One of our closest living relatives, chimpanzees, possess a number of
diverse behaviours observed across a variety of contexts, that are
found in some wild populations while being absent in others. These
include tool use for communication, foraging on insects, algae, nuts,
or honey, and thermoregulatory behaviours such as bathing in pools
or using caves in extremely hot environments. Importantly, some of
these behaviours also show evidence for being socially learned and are therefore considered to be cultural traditions particular to certain
chimpanzee groups. This degree of behavioural variation provides a unique opportunity to investigate the effects of environmental conditions on
both behavioural and cultural diversity within a single species.

Combining fieldwork with in-depth literature search An international team
of researchers led by Ammie Kalan and Hjalmar Ku"hl of the Pan African Programme: the Cultured Chimpanzee (PanAf) at the Max Planck Institute
for Evolutionary Anthropology compiled a data set combining fieldwork
conducted by the PanAf at 46 field sites, plus an in-depth literature
search on chimpanzee research. For 144 chimpanzee social groups they investigated the long-standing question of under which environmental
conditions chimpanzees acquire more behavioural traits. They used
their unique dataset to test whether chimpanzee groups were more likely
to possess a larger set of behaviours if they lived in more seasonal
habitats or habitats where forest cover repeatedly changed over the last thousands of years. The behaviours largely included tool use and more
than half have been described as cultural in previous studies.

The authors found that both recent and historical sources of environmental variability were positively associated with chimpanzee behavioural and
cultural diversity. "Chimpanzees experiencing greater seasonality, living
in savannah woodland habitats and located further away from historical Pleistocene forest refugia were more likely to have a larger set of
behaviours present," describes Kalan. These results suggest that a species closely related to humans also uses behavioural flexibility to adapt to
more seasonal and unpredictable environments. "Since the behaviours we
examined are largely considered cultural, we could further infer that environmental variability also supports cultural diversification in chimpanzees," says Kalan.

Environmental variation as driver for diversification With respect to
human evolution, behaviour is often difficult to study via the fossil
record alone, therefore studies of nonhuman primates such as this one can provide us a comparative insight into the potential selection pressures
that may have been significant in our own past. "Many studies suggest
that environmental variation acts as an important driver for behavioural
or cultural diversification in both humans and animals, but this is some
of the first cross-population data within a single species to support
this idea," says Kalan.

The study has also demonstrated the great potential of a cross-population research approach and it is very likely that it will continue to
provide fascinating insights into the emergence of chimpanzee population diversity.

"While we have learned a lot about the relationship between environmental variability and chimpanzee behavioral diversity in this study, there
may be other demographic and social factors that have also played an
important role in the process of behavioral diversification," says Ku"hl,
a researcher at the Max Planck Institute for Evolutionary Anthropology
and the German Centre for Integrative Biodiversity Research (iDiv). "With continued efforts to study and compare chimpanzee populations at large
numbers, I am convinced that many more exciting discoveries will be made
in the future that will provide further insights into the mechanisms of behavioral diversification in chimpanzees, but that will help us to also
better understand our own evolutionary history." The PanAf continues
to collect species and behavioural annotations from their video camera
traps via Chimp&See. At this platform anyone can watch the PanAf videos
from across the chimpanzee range, and by classifying the species and
behaviours they observe, contribute to the growing PanAf data set.


========================================================================== Story Source: Materials provided by Max_Planck_Institute_for_Evolutionary_Anthropology. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Ammie K. Kalan et al. Environmental variability supports chimpanzee
behavioural diversity. Nature Communications, 15 September 2020
DOI: 10.1038/s41467-020-18176-3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200915121318.htm

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