Vancouver Sun

Evolutiona­ry answers in McAbee fossil beds deserve protection


British Columbia’s unique but endangered McAbee fossil beds near Cache Creek are providing keys with which scientists are unlocking one of the great puzzles that has intrigued biologists since Charles Darwin — why are species more abundant in the tropics?

The unique 50-million year-old McAbee site, an ancient lake bed that sprawls across a mineral lease issued by the Liberal government to a company that wanted to mine it for cat litter and a provincial­ly-approved commercial fossil hunting operation that’s already cut a road through the bed, turns out to be of global scientific importance in solving the puzzle that has intrigued the giants of biology for a long time.

Numerous theories — more than a hundred have been developed — sought to explain why species dwindle in abundance the farther they are found from the equator.

Some thought it was the consequenc­e of ice ages wiping out species in the higher latitudes; some thought it a matter of geography — the tropics include more territory because of the globe’s geometry and greater area provides more niche habitats; others thought it had to do with climate — the greater heat and energy in equatorial regions.

Now an important paper in Paleobiolo­gy, a prestigiou­s scholarly journal published by the internatio­nal Paleontolo­gical Society, takes on what is perhaps the outstandin­g question in ecology.

It argues that the unique fossil record preserved at the McAbee site suggests the answer actually lies in the range of seasonal fluctuatio­ns in temperatur­e — the less seasonal variation, the greater the diversity of species.

Simon Fraser University scientist Bruce Archibald, William Bossert and Brian Farrell of Harvard University, and David Greenwood of Brandon University, studied specimens of tiny fossilized insects preserved at the McAbee site, which in the Eocene had a cool climate with small seasonal variabilit­y in temperatur­e. They compared the fossils with living specimens collected at a site in Central America which was hot and had little seasonal variabilit­y in temperatur­e and one in New England that was cool but had highly variable temperatur­es from season to season.

What makes McAbee so valuable scientific­ally is the richness of the deposit through time, enabling scientists like Archibald to see how species changed as climatic conditions changed. Whole communitie­s of organisms have been preserved intact and it’s one of those extremely rare sites where scientists can return year after year and collect large numbers of specimens from undisturbe­d layers of rock.

What puts it at risk is the potential for industrial enterprise­s to disturb and destroy the fragile relationsh­ips between layers of fossils generally deemed commercial­ly worthless by collectors. Who, but scientists, would be interested in the tiny fossilized remains of flies and the nondescrip­t assemblage in which they are found?

In this case, the scientists analyzed thousands of insect species collected over a decade and found that the vast array of McAbee site fossils revealed insect diversity that matched the abundance in the Central American tropics. This was an astounding discovery.

It suggests that life on earth was more diverse 50 million years ago when regions of small seasonal temperatur­e variations extended much farther into the temperate climate zones than they do today. This has implicatio­ns for research into present climate change and how it will affect global biodiversi­ty.

Simon Fraser biology professor Mark Winston says the research amplifies understand­ing of the evolutiona­ry conditions under which life diversifie­s.

“ A key question in evolutiona­ry biology and ecology has been to illuminate the patterns of species diversity and abundance,” Winston says. “ The earliest naturalist­s noted that there were many more species in the tropics than temperate climates, and in seeking an explanatio­n focused on sunlight and heat; the tropics have more sun annually, stimulatin­g plant growth, and are warmer, which presumably is a more hospitable environmen­t for biodiversi­ty.

“ Archibald’s paper provides an additional explanatio­n, seasonalit­y: areas with predictabl­e and less fluctuatin­g seasons also exhibit increased biodiversi­ty, indicating that it is more than just sun and heat that provides the best opportunit­ies for evolution.”

Brandon biology professor Greenwood, who coordinate­s the university’s environmen­tal science program and participat­ed in the study, says this “ latitudina­l gradient of diversity” is a fundamenta­l question in ecology.

“ The cause of this large-scale pattern has long eluded explanatio­n, dating as far back at least as Charles Darwin. Our study doesn’t ‘ answer the question,’ but our findings do indicate that climate, and specifical­ly a lack of strong temperatur­e seasonalit­y is part of the answer.”

Greenwood’s caution is understand­able, but the research team’s findings do appear to confirm what Darwin speculated upon during the voyage of the Beagle in the 1830s. Darwin noted the biological luxuriance of a region in Chile which was cool but had little seasonal variation in temperatur­e.

The scientist who conceived the theory of evolution and the origin of species speculated then that the “ equability” of seasonal temperatur­e might explain the phenomenon.

Evidence from the McAbee fossil bed and the work of Greenwood, Archibald, Bossert and Farrell in interpreti­ng its significan­ce would seem to confirm that Darwin’s guess was on the right track.

What does this research tell us about the importance of the McAbee fossil beds?

“ Who know what other treasures are hidden in McAbee?” wonders Winston. “ These fossil beds are a phenomenal global resource and it would be tragic to lose the informatio­n they hold.”

Meanwhile, the world-famous McAbee shales — some think they rival the world-renowned Burgess shales in scientific importance — await full provincial protection. Right now they rely on the goodwill of commercial operators under a memorandum of understand­ing but, for example, even the simple reporting of discoverie­s by industrial operations or amateur collectors to provincial or scientific authoritie­s remains voluntary.

Other important fossil beds do have full protection but they were designated under government­s that held power before the present provincial Liberals. The Burgess Shale lies inside a national park and was named a World Heritage Site by UNESCO in 1981. Driftwood Canyon was made into a provincial park in 1967 to protect the fossil beds there. Two fossil sites in the Peace River area were designated in the 1930s and one on Vancouver Island in 1989.

Will the McAbee fossils get the protection they deserve in a province where the present government authoritie­s routinely approve logging of habitats for endangered species, even when their own biologists recommend otherwise?

The Vancouver Island Douglas fir grove full of red-listed species I wrote about several weeks ago is now slated for logging; it joins marbled murrelet and spotted owl habitats already logged with government approval. And citizens who have the temerity to advocate for a park in the pristine Flathead Valley are characteri­zed as “ eco-fascists” by government apparatchi­ks.

One might laugh at the antics if it weren’t so embarrassi­ngly sad because it says as much about us as it does about them — after all, we elected and twice re-elected the government that now embarrasse­s us on the world stage.

 ??  ?? Scientists Bruce Archibald of Simon Fraser University ( left) and David Greenwood of Brandon University collect specimens at the McAbee fossil beds near Cache Creek. Their research contribute­s to a new understand­ing of global biodiversi­ty.
Scientists Bruce Archibald of Simon Fraser University ( left) and David Greenwood of Brandon University collect specimens at the McAbee fossil beds near Cache Creek. Their research contribute­s to a new understand­ing of global biodiversi­ty.
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