We are enforcing our own form of zoological regime change on the world. Much like any other mass extinction, the wholesale alteration of the climate and the environment is pushing thousands of species into permanent oblivion. However, it’s also creating a fair few new species too, and a new study, published in the Proceedings of the Royal Society B, highlights this oft-ignored fact.
Whether it’s through the domestication of animals and plants, genetically modifying flora and fauna to serve our own needs, forced extinctions via hunting, or direct alterations to the environment through deforestation, cityscape expansion, or climate change, we are altering the process of evolution like never before.
By looking at several case studies of organisms brought about by unnatural selection, the team of researchers hope to shine a light on the various ways in which humanity can drive the generation of new forms of life. The evolutionary lineages that are surviving are sometimes developing into incredibly novel species at remarkable speeds, which could be referred to as man-made speciation or even unnatural selection.
Although these new species, some of which are hybrids, can often thrive in this human-dominated world, the authors of the study stress that it doesn’t offset the species extinction rates seen around the planet. In fact, they argue that just comparing the total number of new species to older ones in order to ascertain biodiversity is outdated. Rather, a more nuanced understanding of biodiversity could be gained if researchers focus on what kinds of new species are evolving, and ultimately determining if they came about through indirect human action.
“The prospect of 'artificially' gaining novel species through human activities is unlikely to elicit the feeling that it can offset losses of 'natural' species,” co-author Joseph Bull, a postdoctoral researcher at the Center for Macroecology, Evolution and Climate at the University of Copenhagen, said in a statement. “Indeed, many people might find the prospect of an artificially biodiverse world just as daunting as an artificially impoverished one.”
Image in text: The London Underground mosquito, a new species brought about by man-made speciation. Walkabout12/Wikimedia Commons; CC BY-SA 3.0
A key example of a species that has come about due to infrastructural changes within cityscapes is the “London Underground mosquito.” This used to be the common house mosquito not many generations ago, but a few snuck into the London subway network and bred there. Now, there is a sizable subterranean population so genetically distinct from its surface-dwelling counterparts that the two groups of mosquitos can no longer interbreed.
Another example focuses on the damselfly Megaloprepus caerulatus, a resident of the forests of Central America. Thanks to overzealous deforestation, the species has been divided into several separate population groups, split by the new geography. Now, it’s highly likely that it has fragmented into multiple species within a remarkably short space of time.
Climate change is infamously eradicating much of the Arctic’s sea ice – the very same polar bears like to live on. This has forced them to move further inland, where they are encountering grizzly bears and cross-breeding with them. Consequently, polar-grizzly hybrids are now wandering the North American continent.
The researchers state that it’s impossible to quantify how many man-made speciation events have occurred, but they consider the impact to be quite considerable. In fact, they point out that since the last glacial maximum 11,500 years ago, 255 mammals and 523 bird species have died out, 900 species have been forcefully migrated, we’ve domesticated 470 animals, and now six of the world’s 40 most important crops are entirely new species.
This is nothing short of pandemonium on a global scale.
Image in text: Megaloprepus caerulatus, which is now almost certainly multiple species. Steven G. Johnson/Wikimedia Commons; CC BY-SA 3.0