There are more than 8 million species of
living things on Earth, but none of them—from 100-foot blue whales to
microscopic bacteria—has an advantage over the others in the universal struggle
for existence.
In a paper published Jan. 8 in the
prestigious journal Nature Ecology & Evolution, a trio of scientists
from universities in the United States and the United Kingdom describe the
dynamic that began with the origin of life on Earth 4 billion years ago. They
report that regardless of vastly different body size, location and life
history, most plant, animal and microbial species are equally "fit"
in the struggle for existence. This is because each transmits approximately the
same amount of energy over
its lifetime to produce the next generation of its species.
"This means that each elephant or blue
whale contributes no more energy per gram of parent to the next generation than
a trout or even a bacterium," said co-author Charles A.S. Hall, a systems
ecologist with the College of Environmental Science and Forestry (ESF) in
Syracuse, New York. "We found, rather astonishingly, by examining the
production rate and the generation time of thousands of plants, animals and
microbes that each would pass on, on average, the same amount of energy to the
next generation per gram of parent, regardless of size. A single-celled aquatic
alga recreates its own body mass in one day, but lives for only a day. A large
female elephant takes years to produce her first baby, and lives much longer
than the alga. For all plants and animals of all sizes these two factors - rate
of biomass production and generation time - exactly balance each other, so each
contributes the same energy per gram of parent to the next generation in their
lifetime."
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