You can estimate the total number of species in the world by graphing the decreasing number of new species discovered each year to predict the end point. Or you can extrapolate the number of new species found per hectare of rainforest, to the number of hectares that haven’t been studied.
Or you can graph the body size of each new species found, on the assumption that larger species tend to be discovered sooner, and extrapolate that. The different statistical models over the years have been gradually homing in on a figure of 8.7 million total species. Currently, 1.64 million have been named, so that’s 81 per cent left to find (the 86 per cent figure was based on 2011 totals). This only covers eukaryotes (animals, plants and fungi) though. A 2016 study estimated that bacteria could add almost another trillion species.
Are coywolves a new species?
Coyotes and gray wolves in North America have been able to interbreed, producing hybrid super predator pups commonly referred to as the ‘coywolf’.
Creating a new species is not as easy as it may appear on the surface. DNA testing tells us that the fashionably named ‘coywolf’ is in fact just a variation of a coyote living across eastern Canada and the US.
These adaptive ‘super predators’ carry genes from the coyote, wolf and domestic dog that differ in ratio depending on geographic location. Throughout the last century, deforestation and farming activities caused interbreeding between these biologically similar animals resulting in the evolution of Canis latrans var. – a successful canine mix, but not a genetically distinct species. Yet!
What constitutes a species?
Identifying different species has become increasing complicated.
Species are a naming convenience applied by biologists as they try to group similar animals together. Ernst Mayer defined a species as a group of actually or potentially interbreeding natural populations and this is a working definition that many biologists use.
But there are at least a dozen other ways to categorise species, involving evolutionary history, morphology or DNA analysis. The problem is that evolution doesn’t act on species directly. Natural selection applies at the level of the gene, the individual or the breeding population. Species are just a pattern that appears as a result.
We can easily identify species from a distance, but examine them closely, and the edges blur. The standard definitions of species really break down when you consider single-celled, asexual organisms.