Chris Filardi is the director of Pacific Programs at the Museum’s Center for Biodiversity and Conservation. He has spent his career studying island birds and their unique ecologies, from working with indigenous communities to conserve island ecosystems to tracking the foraging behavior of Palm Cockatoos. At a recent event, Filardi discussed how the genomic revolution and increased access to islands have changed how these systems are studied. He recently answered a few questions about the role islands play in understanding speciation, or how new species arise.
How have island birds shaped modern biology?
Both Charles Darwin and Alfred Russel Wallace traveled to islands, and the birds they encountered inspired the biggest idea in modern biology: the theory of evolution by natural selection. Just as Einstein linked matter and energy, providing a central theorem for modern physics, understanding the origin of new life as the product of heritable natural variation, survival of the fittest, and time transformed all of the life sciences—a revolution grounded in observations of finches’ beaks and the many-colored plumes of island birds.
Why are islands the best places to study speciation?
Since islands are isolated and have relatively small, restricted geographies, their ecologies are simpler to understand. They aren’t covered up in all the layers of interaction you see on continents. On islands, the machinery of evolution is more exposed than in any other context on Earth. Also, isolation releases organisms from the highly competitive communities they face on continents. And, in relative isolation, they can change wildly. For instance, if a parrot can get to an island without mammals, we know it can turn into something like a marmot, becoming flightless, big and chunky, wandering about very un-parrotlike on the ground. Bizarre island life has really strengthened our understanding of how competition and the struggle for ecological space influence diversity.
How has the genetic revolution transformed our understanding of island ecosystems?
Genes enable something unimaginable to Darwin and Wallace: a lens back in time. By reconstructing the genealogical history among populations of organisms, modern molecular biology not only enables comparisons of similarities and differences across space, but also provides a window into patterns of speciation through time. That allows us to test for some of the exact mechanisms driving the initial stages of speciation. It was the stuff Darwin knew was happening but couldn’t see.
What paradigm shifts in island biology have taken place within recent years?
Island species used to be thought of as resulting from one-way colonization events by species from rich continental communities. Though often wonderfully strange or enchanting, island species were thought forever stuck on remote homes, unsuitable for return to competitively “full” continental ecosystems. The Museum’s work on birds has shown that there is a give-and-take in island evolution, that island species are not evolutionary dead ends. They can backtrack to enrich continental diversity and are global engines of diversification in their own right.