This is a little unexpected but worth noting. It also suggests that
coming out of the Ice Age, there has been an additional change in
seasonality that may not yet be accounted for in terms of local
diversity. Certainly that is true in terms of the vegetation as a
review of post Ice Age flora would suggest. There may be merit in
establishing unoccupied niches and then setting out to fill them if
it is beneficial. At least such a strategy would be superior to
accidental release.
We should at least establish the likelihood of such unoccupied
niches.
From that perspective, the introduction of the python into Florida is
not such the disaster it appears, although I certainly do not welcome
its presence. On the other hand I also suspect that we should get
into the business of harvesting surplus carnivores like alligators on
an ongoing basis. Humanity was in the business of harvesting surplus
game and that role in the environment needs to be restored before it
really causes us serious grief. I prefer to not use hyenas or wolves
for that matter.
Ancient insects shed light on biodiversity
by Staff Writers
Burnaby, Canada (SPX) Feb 14, 2013
Simon Fraser
University evolutionary biologists Bruce Archibald and Rolf Mathewes,
and Brandon University biologist David Greenwood, have discovered
that modern tropical mountains' diversity patterns extended up into
Canada about 50 million years ago.
Their findings confirm
an influential theory about change in modern species diversity across
mountains, and provide evidence that global biodiversity was greater
in ancient times than now. The scientific journal Palaeogeography,
Palaeoclimatology, Palaeoecology has published their research.
About 45 years ago, an
evolutionary biologist at the University of Pennsylvania theorized
that change in species from site to site across mountain ranges in
the tropics should be greater than in temperate latitudes.
Daniel Janzen reasoned
that the great difference between summer and winter in temperate
latitudes (high seasonality) offers a wide window to migrate across
mountainous regions. The small difference in the tropics (low
seasonality) allows a very narrow opportunity, annually.
Consequently, communities across tropical mountains should have fewer
of the same species. Many studies examining modern communities
support this theory.
Archibald, Mathewes
and Greenwood realized that fossil beds across a thousand kilometres
of the ancient mountains of British Columbia and Washington provided
a unique lens through which to deepen evaluation of this theory.
Fifty million years
ago, when these fossil beds were laid down, the world had low
seasonality outside of the tropics, right to the poles. Because of
this, if Janzen's theory is right, the pattern of biodiversity that
he described in modern tropical mountains should have extended well
into higher latitudes.
"We found that
insect species changed greatly across British Columbia's and
Washington State's ancient mountain ranges, like in the modern
tropics," Archibald says, "exactly as Janzen's seasonality
hypothesis predicted.
This implies that it's
the particular seasonality now found in the modern tropics, not where
that climate is situated globally, that affects this biodiversity
pattern." He adds: "Sometimes it helps to look to the
ancient past to better understand how things work today."
The findings also
bolster the idea that ancient Earth was a much more diverse world
than now with many more species.
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