E-mail A Friend Tell a friend about the information found on this page by sending them an e-mail.   Your Name: Your E-mail:   Type an e-mail address, then click add: Add a Personal Message: (Optional)

July/August 2010 issue	In this issue Table of Contents Feature: Canada-U.S. Border The Inside Story Editor’s Notebook Reverberations À la carte Mosaic Book Reviews ----------------------------------------------- Past issues

Invasion of the hybrids
The article “Alien species to the rescue?” (June 2010) concludes that “anything that strengthens genetic diversity is welcome.” I’m afraid not.

It is true that genetic diversity in adaptive traits can be very important for the genetic health of a species, and this genetic diversity provides the raw materials that are required by a species to adapt to a changing future. But the idea that anything that strengthens genetic diversity is positive is flawed.

The first flaw in the author’s arguement is the implication that exotic brown anoles [lizards] from Cuba are “better” from a biodiversity perspective than the native green anole populations because their genomes are more diverse. This is inconsistent with the holistic concept of conserving genetic diversity — where each population of each species potentially represents a unique genetic reserve, regardless of how much diversity it contains.

Moreover, the introduction of brown anoles to Florida has been reported to have a negative effect on native green anoles. So what if the presence of an exotic species with relatively high genetic diversity contributes to the regional decline or even demise of a native population or species? Then we potentially have a loss of genetic reserves that are unlikely to be captured elsewhere and a loss of a native species, which, in turn, reduces another crucial component of biodiversity — species diversity.

The second flaw in the article is the suggestion that hybridization is always a good thing for biodiversity. While there are grounds for this argument in very specific instances, this is by no means a general rule. Indeed, when individuals from one population or species cross with individuals from another population or species, the offspring can have lower fitness than those produced by parents from the same population or species. (This is referred to as outbreeding depression.)

Outbreeding depression can disrupt local adaptation from occurring and can disrupt locally co-adapted gene complexes (tightly linked genes).

Alien species may come to the rescue in a small number of very specific instances. But to make such a broad claim misrepresents the meaning of genetic diversity within a biodiversity perspective.

Briar Howes
Ottawa

The article “Alien species to the rescue?” suggests that the hybridization of the invasive coyotes with the endangered eastern wolf population has allowed the hardier traits of the wolves to be preserved in the new coywolves. Unfortunately, the varied gene pool that these hybrids possess has allowed the aggressive nature of wolves to mix with the increasingly urban-savvy behaviour of coyotes, resulting in a breed that will more readily attack smaller animals in urbanized areas. This is becoming a problem in my region.

The real concern with the creation of hybrids is that when animals receive the best of both worlds from parent species, including greater resistance to disease and tolerance of harsh weather conditions, there is the risk of a superspecies emerging that can defy these natural population-curbing factors. That superspecies then becomes a threat to surrounding ecosystems, as it is very difficult to keep the new breeds in check.

The creation of hybrids is often a direct result of human activity, with native species experiencing habitat destruction and climate change, which allows other species to expand into the natives’ territory. We need to pay attention to nature’s warning signs, such as hybridization.

Allison Nicholls
Whitby, Ont.

Not utopian
As a researcher on sustainability and urban issues, I am very aware of Stockholm’s Hammarby brownfields development and was glad to see it referred to in the article “Something old, something green” (Discovery, April 2010), which brought attention to a project of perhaps similar ambition in Québec. However, the story did no one any favours by referring to Hammarby as “utopian,” a euphemism often interpreted as “unrealistically naive.” Hammarby is merely trying to minimize the ecological costs and maximize the human benefits of habitation. I’d suggest there is nothing utopian about that.

Ken Panton
Calgary

Reserved, but not protected
I was delighted to see you giving such a high profile to our new ocean park, Gwaii Haanas National Marine Conservation Area Reserve (“Haida rising,” April 2010). However, there are a few aspects related to Gwaii Haanas of which your readers should be aware.

First, the ocean part of Gwaii Haanas is reserved but not yet protected under legislation, as you imply in your article. The National Marine Conservation Areas (NMCAs) Act was passed in 2002, but currently, there are no areas in Canada protected under this statute. Designation would, indeed, be a cause for celebration.

Second, the article refers to Gwaii Haanas as a reserve. The technicalities of designating protected areas in the ocean are quite complex, and the term “reserve” is commonly used for areas set aside where no extractive activities will be undertaken. Our NMCAs are not like this, and extractive activities will be permitted in most of their area. International scientific opinion is very strong in suggesting that at least 30 percent of each marine habitat must be set aside to prevent the further erosion of marine biodiversity.

These areas, known as “no-take zones,” will be established in Canada’s NMCAs through zoning. Current discussions in Gwaii Haanas suggest that figures of approximately three percent — a tenth of that necessary — are to be protected. It is largely debate over this figure that is causing the protracted delay in establishing Gwaii Haanas as Canada’s first area protected under the NMCA legislation.

Many scientists fear that designating so-called marine protected areas that offer so little in protection will actually do more harm than good. The public celebrates, as it should, the establishment of new areas for protection but has no idea of the very low levels of protection that have been afforded.

that have been afforded. Canada has multiple international commitments to establish a system of NMCAs by 2012. We will not make this target by a long way. Currently, less than 0.5 percent of Canada’s Exclusive Economic Zone (where the country has special rights over the exploration and use of marine resources 200 nautical miles from its coast) is protected, and we rank roughly seventieth in the world in this regard, according to Environment Canada.

We urgently need greater public awareness of this situation to move things forward, and articles such as the one in Canadian Geographic certainly help. Celebrating the designation of Gwaii Haanas as an NMCA would be a joyous occasion. However, I fear we are not quite there yet.

Philip Dearden
Professor and Chair,
Department of Geography
University of Victoria