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magazine / jun10

June 2010 issue

Biodiversity: Invasive Species

Alien Species to the Rescue?  

Naturalists have raised alarms about the growing number of “invasive” species hitching rides to new habitats and devastating local ecosystems. Yet, recent findings say this isn’t such a bad thing.

By Chris Wood
Most often, invasive species don't run amok, but integrate with their new ecosystem.
Photo: Pepin
Interactive map Read more about the hybrid species resulting from invasive genes.

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Multimedia Discover videos, interactive features and photos on the ideas, science and communities behind our biodiversity issue..
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  • What is Biodiversity?

    The word invokes the splendour of our world. In 2010 we celebrate the International Year of Biodiversity, yet many living things are in imminent danger of going extinct. Read more »
  • Clayoquot Sound

    Biosphere Reserves such as Clayoquot Sound aim to prove that rich natural environments go hand-in-hand with vibrant economies. Read more »
  • Citizen Science

    From studying slugs to searching for swans and monitoring pine martens, citizen scientists keep watch over our changing world. Read more »
  • 50 Million Trees

    Ontario has an ambitious plan to reforest the most populated part of Canada. But first it must grapple with landowners and fragmented landscapes. Read more »
  • Goodbye Tallgrass Prairie

    Once covering 6,000 square kilometres in Manitoba’s Red River Valley, the tallgrass prairie has all but vanished from the Canadian landscape.
    Read more »
  • Invasive Species

    Are “invasive” species hitching rides to new habitats all that bad for our ecosystems?
    Read more »
  • Freegan Living

    Gerard Daechsel lives as a freegan, an anti-consumerist who forages necessities from what others throw away.
    Read more »
  • The Jordan Basin

    Six years ago, an ecologically rich wedge of ocean in the northern Gulf of Maine became Canada’s first marine biodiversity showcase. Has it lived up to its promise? Read more »
  • Multimedia

    Discover videos, interactive features and photo essays mapping the ideas, science and communities behind our biodiversity issue.
    View now »

Naturalists have raised alarms about the growing number of “invasive” species hitching rides to new habitats and devastating local ecosystems. But as wildlife genetics illuminate the genome — the ultimate “barcode” for biodiversity — that assumption is proving shaky. The surprising finding: most transplanted species do not dilute genetic diversity in their new locales and may even enhance it.

Read more about the hybrid species born from invasive genes
Read more about the hybrid species born from invasive genes.

“The vast majority of species that establish in a new place do nothing,” says Mark Vellend, Canada Research Chair in Conservation Biology at the University of British Columbia. “Most don’t outcompete the natives or cause diseases or screw up water pipes.”

Most transplants, in fact, integrate uneventfully into their new homes, often displacing but seldom eradicating previous residents.
Most transplants, in fact, integrate uneventfully into their new homes, often displacing but seldom eradicating previous residents and directly enriching local biodiversity in the process. Lizards introduced to Florida from Cuba, for example, possess more diverse genomes than their native cousins.

Squirrels provide a closer-to-home example: the frontier between the ranges of North America’s two species of flying squirrel used to be distinct. Northern flying squirrels occupied conifer and mixed-wood forests from Alaska to Nova Scotia and south-central Ontario. Southern flying squirrels flitted from Florida to the northern fringes of Lakes Erie and Ontario. Encouraged by milder winters in recent years, however, southern flying squirrels have been gliding farther north in recent decades, reaching Algonquin Provincial Park in central Ontario.


Not surprisingly, the two are now interbreeding, says Paul Wilson, Canada Research Chair in DNA Profiling, Forensics and Functional Genomics at Trent University. Far from posing a threat to biodiversity, he proposes, interbreeding may convey advantages to both original squirrel populations. Southern flyers may acquire some of their northern counterparts’ tolerance for cold, he says, in exchange for “genetic material that might give the resident species some advantage to fighting off pathogens that they were not typically exposed to in a previous climate regime.”

A similar dynamic was seen when coyotes pushed beyond their historic range in southwestern United States.

“Where wolves were being extirpated and didn’t readily hybridize with coyotes elsewhere in North America,” says Wilson, “you saw them eliminated from the landscape. But once the coyote hit this eastern wolf range, you started to see hybrids forming, with the genetic potential to become more wolfy or more coyote-like, depending on the environment.”

“In the absence of those coyotes invading,” adds Wilson, “it’s not entirely clear whether there would be much of a remnant left of those eastern wolves.”

While alarm over a minority of alien species is justified, anything that strengthens genetic diversity is welcome. A varied gene pool means hardier species and more resilient ecosystems. Biodiversity starts here.

Related content and resources:
Photo Club
View a gallery of Eamon Mac Mahon’s photos of Canada’s forests and read a one-on-one interview with the photographer.
The International Year of Biodiversity
Learn more about the International Year of Biodiversity and what you can do to contribute to this U.N. initiative.
50 Million Trees
Get involved in your community with Ontario’s 50 Million Tree Program. Donate or organize your own plant, because every tree counts.
Return to the Wild
Explore and learn more about the diversity of Canada’s wildlife in the Return to the Wild project.

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Comments on this articleView all comments (13) | Leave a comment

Teachers and environmental outreach coordinators can run their own Citizen Science project using free online tools at

Submitted by Paul on Friday, March 25, 2016

Citizen scientist can submit wildlife and plant sightings into community database at 'Wildlife & Plant Sightings'

Sightings data are organized into basic reports and easily searchable.

Amateur to professional can contrinute their citizen science here.

Submitted by Paul Lindgreen on Monday, January 24, 2011

This story requires the eyes of an ornithologist on the water counting birds. Birds as indicators tell us about the world below. Having just returned from the Jordan Basin region I can attest to the rich Biodiversity that I saw as I counted birds. Dovekie, N. Fulmar, Greater Shearwater..... This Bioregion is important to both the United States and Canada. It behooves all of us to work together diligently to understand this region of the Ocean. Remember also that it is our RIVER Ecosystems connected to the Gulf of Maine that ultimately determine the biodiversity of the GOM.
Pollution in the GOM is a death sentence. Dioxins and mercury must be removed from the Penobscot River and all streams and culverts must be reconnected to the SEA-RUN FISH.. These are the Keystone Species of the GOM and determine the Health of both the United States and Canadian people.

Submitted by Michael J. Good, MS on Tuesday, November 23, 2010

Good article, but most professional foresters will recongnize that most of the photos do not depict an old growth forests, but a variety of second growth or fire-origin sites.

Submitted by collin on Sunday, June 20, 2010

With respect to the statistics Candace quotes from the Int'l Union for Conservation of Nature Red List Is it 12% of all birds or 12% of all species of birds. Quite a different number I would think.

Submitted by Collin on Sunday, June 20, 2010

The excellent article by Fraser Los entitled “50 million trees” is welcome. While the article focuses on Ontario Government plans to reforest Southern Ontario the author also mentions efforts being undertaken in Northern Ontario. To expand on these remarks…

The Forest Health and Silvicultural Section of the Ministry of Natural Resources advises “in 2008, approximately 92 million trees were planted in Ontario, with 49.8 million of these in the Northwest Region”. Survival rates for Pine Spruce are typically 80 to 85% in the Thunder Bay area and are affected by lack of rain, higher temperatures and frost. Tree plant numbers for 2009 will be available in March 2011.

As one flies or takes a survol by Google over the vast expanse of Northern Ontario, one can’t help but wonder about the sustainability of the Boreal Forest. For example, in some areas notably near the Ogoki reservoir, there are any number of 10,000 hectare clearcuts. Huge areas are unplanted and without sufficient seed trees left standing for natural regeneration. Considerable piles of over cut and uncollected wood lie north of Armstrong. As forest tenure is being renogiated, often with the same companies that have left this mess, Northerners can’t help but wonder if there will be any improvement?

Also, the deplorable conditions experienced by many tree planters, mosty Canadian students, needs examining. Migrant workers picking crops in Southern Ontario have much better accommodation, food and standards than experienced by northern tree planters who are often forced to work in cold rain and snow while sleeping in tents. Certainly miracle planters might attain 5,000 trees under ideal conditions, however most struggle to plant 1,000 or 2,000 trees to meet their camp costs, clothing, travel and to have meagre savings for education.

A article on the future of the Boreal Forest and sustainable forestry in Northern Ontario would be welcome.

Submitted by Paul Filteau on Friday, June 18, 2010

Evolution happens with or without our consent or assistance. Yet it's hard to see the good in some of the growing numbers of invasive plant species. Good article, thanks.

Submitted by Tina on Wednesday, June 2, 2010

Informative and well-written article. Nice to see attention being paid to this important, though sadly neglected, issue in Manitoba.

Submitted by Tom Penner on Friday, May 28, 2010

Here is a slideshow from this year's Guelph Rotary Forest tree planting at wich about 1,000 people helped plant trees:

Submitted by Janet Baine on Thursday, May 27, 2010

We should cherish and protect the old-growth rain forests and what's left around us.

Submitted by james on Thursday, May 27, 2010

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