We're in the middle of a global biodiversity crisis. Extinction rates of nearly all groups of organisms—insects, mammals, plants, fish—are through the roof, with very scary estimates for how much could be lost in the next 20 years. Like, permanently lost.
In order to prevent the complete loss of important ecosystems on which we depend, governments and agencies from around the world are engaged in many conservation efforts. The issue is so grand in scope, a whole science has been devoted to it—conservation biology. There are some difficult and important questions and issues in conservation biology, and many of them revolve around species concepts.
It all starts with a few basic questions. How do we preserve biodiversity? What are the highest priorities? What are we even conserving?
There have been two major strategies to get at these questions: preserving places and preserving species. The place-based approach attempts to conserve land and wild places in order to protect the biodiversity that lives there. Even this place-based approach is truly species-influenced. The most obvious places to conserve are those with high biodiversity (lots of species) and/or are the most threatened (lots of species at risk). No matter which way you slice it, most conservation issues are phrased in terms of species. Rare species. Important species. Threatened species. Places with high species diversity. If you think defining a species is tricky in biology, try mixing it with politics.
How can we expect policy-makers, conservationists, and politicians to have a firm handle on species conservation when biologists aren't always sure what a species is? Choosing a species concept can have a surprising impact on conservation plans. One study published in the journal Conservation Biology looked at the number of birds that were endemic to the mountains of southern and western Mexico. Endemic means that a species is native to one location and is found nowhere else on earth. Because of their restricted distributions, endemic species are often high conservation priorities. The study identified 101 endemic bird species under the biological species concept (BSC), but a whopping 249 species if the phylogenetic species concept was used instead. That's a huge difference. Which one should be used? You tell us.
The Endangered Species Act (ESA) is the USA's primary legislation responsible for listing and managing protected species. The ESA doesn't follow an official species definition, although traditionally it has relied on the BSC when making decisions about which species to list and protect. Since we know all about the limitations of the BSC, we might guess that this could get a little tricky, especially when biologists are concerned with protecting biological entities that don't quite fall into the species category, like hybrids, subspecies, and threatened populations.
Luckily the ESA allows for the listing and protection of subspecies and subpopulations (as long as they're biologically justified), but hybrids have proven a bit trickier. In fact, even though there are cases of pretty cool threatened hybrids (the US's red wolf) that probably warrant protection, they are usually not covered because the ESA typically follows the BSC. According to the BSC, hybrids are not biologically relevant species. Bummer.
Strong species bias is another common flaw in many conservation policies in the US. The cutest, cuddliest animals should be conserved. No one is debating that. What about the ugly, semi-frightening ones? We are all a little guilty of species-ism. If one of our conservation goals is to protect the ecosystems functions important to human lives, (for example, water filtration, soil building, carbon sequestration, and pollination) it's probably just as important to protect the worms, bacteria, insects, and slime molds of the world.
Species conservation questions are often difficult to answer and can mean life or extinction for some species. Should subspecies always be eligible for protection? Is it okay to protect some populations of a threatened species and not others? How many species is enough? Is saving some rare desert beetle really worth the money and manpower? What are our ethical responsibilities as humans? Who knew species concepts could weave such a philosophical, ethical, and political web?