What’s a species? What separates one species from another? The word may be a handy abstraction but it’s also fuzzy. Our words aren’t as precise as we might hope.
Consider the evolution of a new species of bird, in two generations, from a single lost finch spotted by a graduate student.
The arrival 36 years ago of a strange bird to a remote island in the Galapagos archipelago… mated with a member of another species resident on the island, giving rise to a new species that today consists of roughly 30 individuals.
The newcomer was a male that sang a different song, and was much larger with a larger beak than three finch species living on the island. Because the island was small and intensely studied, researchers were able to collect blood samples of the new male and track his breeding.
A species is a population that interbreeds within its own group but not outside. That doesn’t mean individuals can’t or won’t breed outside their group – and produce offspring that can also breed. Some species are isolated because they because they never bump into each other.
“Reproductive isolation is considered a critical step in the development of a new species.” The new male’s offspring looked different and sang a different song than the fiches around them. Since they had each other, they weren’t as desperate (or lucky? insistent?) as their father, so they mated with each other. That’s why they’ve been awarded the title of species.
Such intense inbreeding can exaggerate genetic diseases and weaknesses, but that isn’t obvious yet for these finches. Who knows? Problems may arise. Perhaps we’ll watch the demise of this new species in coming years.
This new species may say more about people than birds. The Galapagos finches continue to be fascinating birds, utterly unconcerned about human-created concepts, taxonomy, or language.
More at phys.org/news and many other outlets.