National Geographic Society Newsroom

Alien Ants Prevent Geckos Pollinating Endangered Flower

The critically endangered Roussea flower has been vanishing from Mauritius, an island in the Indian Ocean. Now scientists have figured out why. “The blue-tailed gecko is the only pollinator and seed disperser for the flower,” says biologist Dennis Hansen. But alien ants that have invaded the island “have also taken a liking to the flower...

Lizard-ant-1.jpgThe critically endangered Roussea flower has been vanishing from Mauritius, an island in the Indian Ocean.

Now scientists have figured out why.

“The blue-tailed gecko is the only pollinator and seed disperser for the flower,” says biologist Dennis Hansen. But alien ants that have invaded the island “have also taken a liking to the flower and are scaring the gecko away.”

It’s a case of an invasive species causing serious disruption to an ancient arrangement between gecko and plant.

Phelsuma-&-Roussea3.jpgThe endemic blue-tailed day-gecko Phelsuma cepediana is the sole pollinator and seed disperser of the critically endangered endemic plant Roussea simplex, Hansen, now at Stanford University, and Christine Müller from the University of Zurich, Switzerland, write in a paper published in the current issue of the journal Biotropica.

“The flowers and fruits are often visited by the invasive ant Technomyrmex albipes, which forages on the nectar and fruit pulp, and tends honeydew-producing mealybugs on the fruits,”

the researchers write.

Lizard-ant-5.jpgThe scientists explored how the presence of the alien ants influence geckos foraging at flowers and fruits of R. simplex by removing and excluding ants from flowers and fruits.

“Gecko visitation rates to ant-free control flowers and fruits, and flowers and fruits where ants had been removed and excluded, were higher than those to ant-infested flowers and fruits,.” they write. The resulting seed set of ant-infested flowers was greatly reduced, compared to ant-free control flowers.”

“Similarly, for fruits with ants, very few seeds were likely to be ingested and dispersed by the geckos.”

Thus, the researchers concluded, the ants monopolize flowers and fruits of R. simplex, and prevent access of pollinating and seed-dispersing geckos by aggressive interference competition.

For a critically endangered plant like R. simplex, “this is of urgent conservation concern,” the researchers noted in their paper. Unless the ants are removed, the Roussea “is going to be in really big trouble in the not too distant future.”

Lizard-ant-3.jpg

About National Geographic Society

The National Geographic Society is a global nonprofit organization that uses the power of science, exploration, education and storytelling to illuminate and protect the wonder of the world. Since 1888, National Geographic has pushed the boundaries of exploration, investing in bold people and transformative ideas, providing more than 14,000 grants for work across all seven continents, reaching 3 million students each year through education offerings, and engaging audiences around the globe through signature experiences, stories and content. To learn more, visit www.nationalgeographic.org or follow us on Instagram, Twitter and Facebook.

Meet the Author

David Max Braun
More than forty years in U.S., UK, and South African media gives David Max Braun global perspective and experience across multiple storytelling platforms. His coverage of science, nature, politics, and technology has been published/broadcast by the BBC, CNN, NPR, AP, UPI, National Geographic, TechWeb, De Telegraaf, Travel World, and Argus South African Newspapers. He has published two books and won several journalism awards. In his 22-year career at National Geographic he was VP and editor in chief of National Geographic Digital Media, and the founding editor of the National Geographic Society blog, hosting a global discussion on issues resonating with the Society's mission and initiatives. He also directed the Society side of the Fulbright-National Geographic Digital Storytelling Fellowship, awarded to Americans seeking the opportunity to spend nine months abroad, engaging local communities and sharing stories from the field with a global audience. A regular expert on National Geographic Expeditions, David also lectures on storytelling for impact. He has 120,000 followers on social media: Facebook  Twitter  LinkedIn