Do Butterflies Challenge the Meaning of Species?
What is a species? It’s a question that has agonized scientists since well before Darwin. With some exceptions, the thinking has landed on an evidently firm reproductive barrier: Members of different species don’t mate. If they do, their offspring are sterile and can’t contribute to future generations. The reproductive barrier has thus created a useful demarcation of “what is a species”—until a deep dive into butterflies showed otherwise.
Researchers recently analyzing the genomes of every butterfly species in the United States and Canada—845 in total—have revealed that at critical evolutionary intervals, butterfly species have crossed the reproductive barrier, mating with, it turns out, plays a pivotal role in how life forms evolve. The tree of life may never look the same.
