Population density
and body size in mammals
By John Damuth
Foreword by Aistair
Evans
John Damuth is a
research scientist at the University of California Santa Barbara Marine Science
Institute. His research includes ecological correlates with body size.
Alistair Evans is a
Research Fellow and Senior Lecturer at Monash University. His research includes
the evolution, development, and function of animal morphology.
Body size is very important to an organism. From an
ecophysiological perspective, body size is very closely linked to the energy
input in the environment (Bergmann’s Rule, Temperature-size Rule). What does
that look like at the population level? To answer that question, Damuth
compiled data from herbivorous mammals. More specifically their body size and
population abundance, which he compared with metabolic rate. What he found was
that while body size grows
exponentially with energy use, population abundance decays at an equal rate. Which makes sense. The energy has to be
conserved somehow.
Questions:
How do these manifest at the community level? My first
thought is how it would work as a mechanistic explanation for the “ten percent
rule” but are there other ways they interact?
The data used was strictly for mammalian herbivores, and showed there was no correlation, as energy used by a local population is independent of its body size. Is the same true of other orders of mammals such as carnivore populations?
ReplyDeleteIt's striking how the W exponents cancel out so cleanly.
ReplyDeleteIf I'm following this right - does this mean that the transfer of energy is independent of the mass of the herbivore? Also, does can the basal metabolic rate apply to all species in different habitat etc?