The role of brain size on mammalian population densities
Por:
Gonzalez-Suarez, Manuela, Gonzalez-Voyer, Alejandro, von Hardenberg, Achaz, Santini, Luca
Publicada:
1 mar 2021
Resumen:
The local abundance or population density of different organisms often
varies widely. Understanding what determines this variation is an
important, but not yet fully resolved question in ecology. Differences
in population density are partly driven by variation in body size and
diet among organisms. Here we propose that the size of an organism'
brain could be an additional, overlooked, driver of mammalian population
densities.
We explore two possible contrasting mechanisms by which brain size,
measured by its mass, could affect population density. First, because of
the energetic demands of larger brains and their influence on life
history, we predict mammals with larger relative brain masses would
occur at lower population densities. Alternatively, larger brains are
generally associated with a greater ability to exploit new resources,
which would provide a competitive advantage leading to higher population
densities among large-brained mammals.
We tested these predictions using phylogenetic path analysis, modelling
hypothesized direct and indirect relationships between diet, body mass,
brain mass and population density for 656 non-volant terrestrial
mammalian species. We analysed all data together and separately for
marsupials and the four taxonomic orders with most species in the
dataset (Carnivora, Cetartiodactyla, Primates, Rodentia).
For all species combined, a single model was supported showing lower
population density associated with larger brains, larger bodies and more
specialized diets. The negative effect of brain mass was also supported
for separate analyses in Primates and Carnivora. In other groups
(Rodentia, Cetartiodactyla and marsupials) the relationship was less
clear: supported models included a direct link from brain mass to
population density but 95% confidence intervals of the path
coefficients overlapped zero.
Results support our hypothesis that brain mass can explain variation in
species' average population density, with large-brained species having
greater area requirements, although the relationship may vary across
taxonomic groups. Future research is needed to clarify whether the role
of brain mass on population density varies as a function of
environmental (e.g. environmental stability) and biotic conditions (e.g.
level of competition).
Filiaciones:
Gonzalez-Suarez, Manuela:
Univ Reading, Sch Biol Sci, Ecol & Evolutionary Biol, Reading, Berks, England
Gonzalez-Voyer, Alejandro:
Univ Nacl Autonoma Mexico, Inst Ecol, Dept Ecol Evolut, Mexico City, DF, Mexico
von Hardenberg, Achaz:
Univ Chester, Dept Biol Sci, Conservat Biol Res Grp, Chester, Cheshire, England
Santini, Luca:
Radboud Univ Nijmegen, Inst Wetland & Water Res, Dept Environm Sci, Fac Sci, Nijmegen, Netherlands
CNR, Natl Res Council, Inst Res Terr Ecosyst, IRET, Rome, Italy
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