~ page 4 April 15,1986 .

 

Meet the Beetles °°"...

Graphics by Cliff Almas

Fossil beetles are helping
today’s scientists learn more
about the climate before,
during, and immediately after
the last ice age. Studying
which beetle species lived in
a particular location at a given
time helps researchers re-

construct that — prehistoric
environment.
Dr. Alan  V. Morgan,

Professor of Earth Sciences at
the University of Waterloo, is
ofie Of a handful of paleoento-
mologists (those who study
fossil insects). Parts of
insects’ hard, chitinous bod-
ies, even to colour patterns,
hairs, and scales, can be well
preserved as fossils even after
two million years.

Beetles have been around

for a long time. They outlived

the last dinosaurs by 60 mil-
lion years, and preceded

mammals by 50 million years. °

One in five living things is an
insect, and well over a third
of all insect species are
beetles.

Many beetle species have
quite specific living require-
ments. Some live only on
certain types of trees. Others
live only in’ the dung. of

» certain animals. Some: nibble

a ®

away at the leaves of specific
plants. These — preferences
have remained _ relatively
thousands - or even mill-
ions of years, around the
world.

Beetles also seem to be

opportunistic colonizers.
Taking advantage of their low
position in the food chain and
their mobility, they move
quickly into a new region
when conditions there become
suitable for their particular
lifestyle.

The combination of the
beetles’ _ specific living re-
quirements and ability to
rapidly colonize suitable en-
vironment means that fossil
beetles provide a clue to past
climate. The climate where
any beetle fossil lived would
have been pretty much iden-
tical to the climate in areas
where the same type of beetle
lives today.

So the particular com-
munity of beetles that lives in
any environment now is a
guide to past climates,
because their ancestors would
have lived in almost identical
conditions, though perhaps in
a different region.

Dr. Morgan is now using
his knowledge of these insects
to reconstruct the past climate
curves in the Toronto region.
He has examined the fossils
of beetles from the Don
Valley brickpit’s Sangamon
8 et e s

 

go

level, perhaps 100,000 years
old.
The species of beetles

found there are types which
would live in a climate almost
identical to that of Toronto
today : a mixed deciduous/
coniferous woodland, border-
ing a_ well-vegetated and
slow-moving river flowing
into a lake. The July average
temperature would have been
about 20 degrees C.

In contrast, beetles from

the lower part of the
Scarborough Bluffs (about
70,000 years old) indicate a
vastly different climate.
These insects - whose de-
cendants now live in the
Northwest Territoties - inhab-
ited a patch spruce environ-
ment, with some open
ground, with a mean July
temperature of 12 degrees C.
The Scarborough formation
rests on top of the Don’s
Sangamon layers. The climate

obviously changed between
the two strata as a result of
the advance of the glaciers of
the Wisconsin ice age (from
75,000 to 10,000 years ago),
which turned the Toronto area
into a tundra-like environ-
ment, Dr. Morgan says.

The climate fluctuations of
the Pleistocene era (the era of
the ‘‘Ice Ages’’, which began
more than one million years
ago) caused beetle populat-
ions to migrate vast dist-

ances. Their present distri-
bution is quite different from
what it was during much of
the Pleistocene.

The beetles presently in
Canada would ony have been
able to live here between the
ice ages, or since the last ice
retreated between 7,000 and
15,000 years ago.

Dr. Morgan’s research has
been supported by the
Natural Sciences and Engine-
ering Researching Council.

 

 

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