Butterflies are perhaps one of the world’s most-loved insect species. Not only are they harmless, but they sport beautiful, colorful wings that vary from one species to the next.
Despite how beautiful they are, researchers are discovering ugly trends regarding their populations, citing how urbanization is having an adverse impact on their genetic diversity and increasing their likelihood of imminent extinction.
Image Credit: Pixabay
The findings of the latest study to delve into the genetic diversity of butterflies in urbanized regions have been published in the journal Heredity.
“Our research illustrates what is probably a widespread phenomenon: a drastic reduction in diversity in urban areas. We were able to quantify this trend and show that it's a problem that needs to be taken seriously,” explained Estelle Rochat, a Ph.D. student from the EPFL's Laboratory of Geographic Information Systems (LASIG) and an author of the study.
Rochat and her team grabbed genetic samples from the small white (Pieris rapae) butterfly in both densely-populated areas and scarcely-populated areas for comparison. At least 145 genetic samples were captured studied side-by-side with more than 1,600 samples in an existing database.
The findings revealed that Pieris rapae was up to 60-80% less diverse in densely-populated areas than they were in the scarcely-populated areas, which exhibited only about 16-24% diversity loss. Moreover, butterfly populations were smaller in highly-urbanized areas than they were elsewhere.
The team also utilized computer simulations to discern whether future generations of small white butterflies would continue to experience diversity issues as the world maintains a steady urbanized makeover. Sadly, the results showed that they would indeed.
Two very alarming facts can be drawn from the results: 1) that the small white butterfly is suffering from consanguinity in densely-populated and urbanized areas, and 2) that they’re having more difficulties reproducing because high-rising buildings and other obstacles are fragmenting them from one another.
“We saw a huge difference in population persistence between downtown and the suburbs. Butterflies in highly urbanized areas had very little space to move around, and it was harder for them to encounter other butterflies of the same species to reproduce,” Rochat continued.
“They showed a substantial degree of consanguinity, which reduces their ability to survive and adapt to their environment and could eventually lead to the disappearance of the species.”
The study paints a disturbing image for butterflies, but we can help by planting more balcony or roof gardens to contribute to a welcoming environment for butterflies that encourages them to mate. It's a necessary component in extending genetic diversity in lacking regions; on the other hand, it’s only a temporary solution to the problem.
Overall, the only sure-fire way to fix the problem is to design our future cities with butterflies in mind. Many are lacking the greenery they need today, and that has to change if we're going to save a host of butterflies from extinction.