Understanding the curiosities of islands and what makes places like Catalina unique inspired a recent visit by podcaster and educator Michelle Fullner. Her podcast Golden State Naturalist is ranked among the top 1% of podcasts worldwide. She explained in her newly released episode the concept of island biogeography, the study of how life is distributed on islands. 

When she arrived on Catalina, Fullner was picked up at the ferry port by Kevin Alison, the Conservancy’s native plant manager. As they drove to Middle Ranch to tour the Ackerman Native Plant Nursery and learn more about the Conservancy’s work. Alison explained to Fullner the specific adaptations of plants on Catalina compared to their mainland counterparts.  

While many plants on the mainland have thorns, waxy coatings and other features designed to protect them against grazing, plants on the Island have frequently evolved without them. Defenses require energy and when a plant is not under threat by grazers or other environmental factors, it stops spending energy on those qualities. Grazing and browsing animals weren’t introduced to Catalina until the 1900s, so many of its plants are not equipped with natural defenses against invasive deer. Alison explained the impact on the endemic Catalina Ironwood (Lyonothamnus floribundus), which only has about 119 individuals remaining on an island where it once flourished. 

“It’s been thousands and thousands of years of this history and evolution and 93 years ago, we brought deer to the island for hunting, and it’s nearly wiping this plant out of existence,” explained Alison.

Alison, who is working on innovative science to clone rare plants, has dedicated his career to the important work of preserving the native plants on islands. As the episode explains, islands represent just 5.3 percent of earth’s land area, but they are home to about 20% of the planet’s species across all domains of life. About 21% of plants are endemic to islands, meaning it exists only in that place and nowhere else.

The study of how life is distributed on islands is called island biogeography. This episode of Golden State Naturalist set out to understand the intricacies of island species and the way these species evolve in a confined landscape. Scientists have long studied these evolutions and have discovered fascinating changes, such as major changes to the size of mammals, influences on birds’ ability to fly, and shifts in how animals behave around humans.

John Knapp, Conservancy senior conservation scientist, met with Fullner to share insights on the ecology of plants like giant buck-wheats, island foxes, and what islands teach us about the living world back on the mainland. Knapp spent years working to eradicate weeds that were threatening different plant communities on Catalina Island. His work now focuses on conserving native plants.

“Over time as that plant evolves, it starts with a very low diversity of genetic material within that one individual,” Knapp said about the evolution of new arrivals on islands. “Their behavior might change as well.”

Knapp gave examples of island species that look and behave differently than their mainland counterparts. Fullner asked why it’s so much easier to observe evolutionary changes on islands.

“Islands make very good laboratories for research projects because you don’t have as many inputs,” he said. “When you have not as many species to look at, it’s much easier to focus in on one and see those differences.”

The podcast is available on Spotify and Apple. Stay tuned for future topics related to Catalina Island on The Golden State Naturalist.