People typically think about evolution as a linear process where, within a species, the classic adage of “survival of the fittest” is constantly at play. New DNA mutations arise and get passed from parents to offspring. If any genetic changes prove to be beneficial, they might give those young a survival edge.
Over the great span of time – through the slow closing of a land bridge here or the rise of a mountain range there – species eventually split. They go on evolving slowly along their own trajectories with their own unique mutations. That’s the process that over the past 3.5 billion years has created the millions of branches on the evolutionary tree of life.
However, new genome sequencing data reveals an unexpected twist to this long evolutionary story. It turns out that the boundaries between species on their own branches of this tree are a little more permeable than previously thought. Rather than waiting around for new mutations to solve a particular problem, interbreeding between different species can introduce ready-made genetic advantages.
Unraveling the story of life, one genome at a time
The author with a red-faced warbler (Cardellina rubrifrons), one of the wood warbler species included in the study.
Kevin Bennett
As an evolutionary biologist, I’ve been studying the stories written in the genomes of animals for over two decades. I focus mostly on colorful songbirds called wood warblers that hail from North, Central and South America. There are approximately 115 species in total, and they come in a dazzling array of bright colors.
Some of these birds might be familiar to you, such as the brilliant Blackburnian warbler (Setophaga fusca), which lights up the tops of the pine trees in the eastern forests of the U.S. and Canada during spring and summer. Other warbler species might be less familiar, like the pink-headed warbler (Cardellina versicolor), which lives only in the highlands of Guatemala and southern Mexico.
The story of these New World warblers was written within the past 10 million years or so – relatively recently in evolutionary terms. They’re all, in effect, “evolutionary neighbors,” sitting next to each other at the tips of the crown of the tree of life. In my team’s most recent work, led by evolutionary biologist Kevin Bennett, we gathered a massive amount of data from warbler genomes – over 2 trillion base pairs, from nearly every species of warbler – to learn more about their evolutionary history.
We found that some species have unexpectedly leaped over evolutionary hurdles by sharing solutions to evolutionary problems. We are now learning from this kind of data that species aren’t just vertical, evolutionary silos, as we once thought. Instead, there is much more horizontal “cross talk” among the branches of the evolutionary tree.
These warblers now join Amazonian butterflies, cichlid fish in Africa, as well as our own hominid…
