Heat, Not Light, May Be Real Engine Driving Biodiversity

Question: If the following is true, should we then expect an increase
of species diversity at the high altitudes (mountain peaks) and high
latitudes ( the poles)?

Partial answer? :  In the past couple weeks, I posted info here which
indicates an increased diversity already showing up on and near
mountain peaks (high altitude).


P.S. Heat can also kill. And it can inhibit milk production in
mammals, posing a risk to survival and nurturance of young animals.

Science Daily
May 29, 2008

Heat, Not Light, May Be Real Engine Driving Biodiversity

What causes tropical life to thrive: temperature, or sunlight? The
answer is not necessarily “both.” It turns out that the explosion of
species at the tropics has much more to do with warmth than with
light. (Credit: Copyright Michele Hogan)

ScienceDaily (May 29, 2008) – What causes tropical life to thrive:
temperature, or sunlight?

The answer is not necessarily “both.” According to a study recently
published online in PNAS Early Edition, the explosion of species at
the tropics has much more to do with warmth than with light.

“The diversity was unrelated to productivity (from photosynthesis),
but it was strongly related to temperature,” said University of
Southern California biologist Jed Fuhrman, who led a group that
analyzed bacterial samples from warm and cold oceans.

Fuhrman’s group found far greater diversity in samples taken near the
equator. In particular, samples from low-productivity waters still
contained many bacterial species, suggesting that photosynthesis has
little influence on diversity.

Many researchers have tried to separate the influence of temperature
and sunlight, Fuhrman said, but have found it hard to do by studying
higher organisms.

Bacteria are ideal subjects because of their wide distribution and
the recent availability of genetic fingerprinting, he added.

The question of what drives diversity is important to biologists who
seek to uncover the basic rules governing life.

“Is diversity ruled by fundamental laws, and if so, what is the basis
of them?” Fuhrman asked.

The so-called kinetic law links the rates of metabolism, reproduction
and many other biological processes to the motion of atoms and
molecules. Such motion increases with temperature, presumably
speeding up the biological processes.

Fuhrman calls this “the Red Queen runs faster when she is hot” hypothesis.

Productivity also is thought to promote diversity by increasing the
food supply. This is “the larger pie can be divided into more pieces”

The two hypotheses may both be valid, Fuhrman said, but his group’s
results show that “the kinetics of metabolism, setting the pace for
life, has strong influence on diversity.”

Biologists have known for centuries that animal and plant
biodiversity is greatest at the tropics, though they have not agreed
on whether temperature or productivity was the cause.

The Fuhrman group is the first to show that bacteria follow the same
pattern. And as the PNAS study shows, bacteria are useful vehicles
for probing the causes of biodiversity.

Fuhrman, holder of the McCulloch-Crosby Chair for Marine Biology in
the USC College of Letters, Arts and Sciences, has been studying
bacteria since the early 1980s, when new instruments and techniques
greatly improved scientists’ ability to identify microbial species.

Since then, marine biologists have realized that bacteria play a
dominant role in the oceans. More than half the carbon dioxide
respired by marine organisms comes from bacteria, Fuhrman said.
Bacteria also comprise most of the diversity on earth, control vital
biogeochemical cycles, and form an integral part of the food chain.

“I study them because, even though they’re invisible, they’re
incredibly important,” Fuhrman said.

Fuhrman was first author on the PNAS paper. His co-authors were USC
graduate students Joshua Steele, Ian Hewson, Michael Schwalbach and
Mark Brown; University of Oregon, Eugene biologist Jessica Green; and
last author James Brown, from the University of New Mexico,

The National Science Foundation supported the group’s research.
Adapted from materials provided by University of Southern California,
via EurekAlert!, a service of AAAS.

University of Southern California (2008, May 29). Heat, Not Light,
May Be Real Engine Driving Biodiversity. ScienceDaily. Retrieved May
29, 2008, from


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