After up to two million years of separate evolution, two types of common raven have been ‘caught in the act’ of consolidation, say scientists
Fri 2 Mar 2018 10.00 GMTLast modified on Fri 2 Mar 2018 23.25 GMT
Speciation, where one species diverges into two, is a well-known concept in the theory of evolution. But a new study based on almost 20 years of research has revealed that “speciation reversal”, the merging of two previously distinct lineages, may also play an important role.
Scientists have discovered that two lineages of common raven that spent between one and two million years evolving separately appear to be in the process of such a consolidation. The findings raise intriguing questions about how science should define species – and whether the boundaries are as clearcut as once thought.
“The bottom line is [speciation reversal] is a natural evolutionary process, and it’s probably happened in hundreds, or almost certainly thousands, of lineages all over the planet,” said Kevin Omland, professor of biological sciences at University of Maryland, Baltimore County (UMBC) and co-author of the new study. “One of our biggest goals is to just have people aware of this process.”
Omland first began studying the raven 20 years ago, after he began to suspect that two separate species could have been lumped together. He reported the existence of two lineages: one concentrated in the southwestern United States, dubbed “California,” and another found everywhere else (including Maine, Alaska, Norway and Russia) called “Holarctic”.