From the Winter 2024 issue of Living Bird magazine. Subscribe now.
Recent research has discovered the ability of an endangered Willow Flycatcher population to undergo genetic modification to adapt to climate change.
In a study published in the journal Nature Climate Change in June, researchers documented a genome-wide shift within a population of Willow Flycatchers in San Diego, which scientists believe is equipped with an unmistakable brownish -olive songbird to better deal with increasingly wet and humid conditions in coastal southern California.
The Southwestern Willow Flycatcher has been federally protected under the Endangered Species Act since 1995. One of four subspecies of the Willow Flycatcher, it has a range in seven states from Texas to California. Many Southwestern Willow Flycatchers in San Diego live in wet willow thickets along the San Luis Rey River, an area that has experienced increased variability in rainfall patterns and rising temperatures over the past several decades.
For the study, scientists analyzed 616 flycatcher specimens dating back to the early 1900s, including 23 specimens from the Cornell University Museum of Vertebrates. They found that the genetic structure of most Southwestern Willow Flycatchers remained unchanged outside of San Diego. However, when the team performed a whole-genome analysis of Southwestern Willow Flycatchers from San Diego, and compared it to San Diego flycatcher specimens from more than 100 years ago, they found that current flycatchers have more high prevalence of gene variants associated. with adaptation to wet and humid conditions.
According to Sheela Turbek, a postdoctoral fellow at Colorado State University and lead author on the study, this genetic change likely stems from interbreeding with other Willow Flycatcher populations. At some point in the last century, Willow Flycatchers from across the Southwest and from the Pacific Northwest (a separate subspecies) exchanged genetic material with Willow Flycatchers in San Diego. This mixing with neighboring populations introduced new genetic material to the breeding of the Southwestern Willow Flycatcher in San Diego and may have caused an evolutionary response to climate change that appears in the genome of modern San Diego birds.
Leonardo Campagna, an ornithologist who was not involved in this research, said that the findings from this paper show why it is important to maintain large and interconnected populations of any organism.
“The best way to do that is to protect the habitat and the movement of individuals across the landscape,” said Campagna, who is assistant director of the Fuller Evolutionary Biology Program at the Cornell Lab of Ornithology. “Large healthy populations will have more genetic diversity, and are therefore better equipped to respond to natural selection and adapt in the direction they may need to go.”
