Discover the strewing results of a butterfly incursion on genetic variance: a species infiltrating Europe in rapid succession and amid urbanization.
The Incredible Journey of a Butterfly
Previously limited to a few tiny colonies in Switzerland, the southern small white butterfly has expanded its range across Europe in one of the most impressive examples of insect migration ever recorded.
With its four-centimetre wingspan and black-and-white markings, this unassuming insect was once a rarity north of the Alps. Yet in the past two decades, it has been racing across the continent, extending its range clear to the North Sea and as far east as the Czech Republic.
That it did so in its own genetic diversity is especially interesting. As the southern small white colonises new areas, however, it is actually replacing the original local populations with its own kind and thereby alowing genetic homogenisation of this newly expanding species.
How Urbanization Factors into the Spread
You see, the reason why the southern small white has spread so rapidly is simple: it turns out that this species really likes human-created habitats! Unlike the many butterfly varieties, prefer an undisturbed natural environment, this butterfly does well in urban and suburban areas.
And the secrets to its survival are probably its favourite foods of arugula and candytuft – both abundant in gardens and landscaping. However, as the forcibly built environment of man has opened up to them they have found plenty of resources to enable it flourish in new areas by displacing native butterfly species.
Furthermore, the southern small white can complete five or six generations per year in regions of temperate winter allowing for rapid expansion in recently colonized areas. This has been the cause of its spectacular spread across Europe; it both grows and spreads rapidly.
Conclusion
The invasion of this southern small white butterfly is a complex phenomenon with numerous consequences, some good and some rather less so. The greater prevalence of the species may offer some resistance to extinction, but if their genetic pool is homogenized there will be even more reason for worry.
If re-urbanization shapes something, it is not the town-like nothingness itself but its ecological extension. The story of the southern small white is a lesson demonstrating that delicate balance. In the future, it will be important to understand and minimize the impact of these invasive species on the diversity of life on earth.
