The survival of this parasitic plant could depend on a rare rabbit

The survival of this parasitic plant could depend on a rare rabbit

On a small island chain off the coast of Japan, local biologists found a peculiar bite mark on the Balanophora yuwanensis plant. They surmised that the toothy print might belong to the Amami rabbit, a wild, dark-furred nocturnal creature named after the Amami Islands. The rabbit evolved separately on the islands, making it genetically distinct from other species in Japan. So the team installed infrared-activated cameras near the B. yuwanensis, a non-photosynthetic plant, and spent 52 days observing which animals eat it.

His suspicions were correct: of all the animals in the forest, the rabbit Amami feasted on the fruit grown in the forest. B. yuwanensis plant more. The team’s observations were later confirmed when they studied the rabbit’s feces. The Kobe University article was published in the journal Ecology Monday. Furthermore, the researchers found that the rabbit could be critical to the plant’s survival. After the Amami rabbit eats the fruit, it expels the seeds and scatters them throughout the island’s evergreen subtropical forests.

Seed dispersal by animals is particularly important for the B. yuwanensis plant. Although the plant’s seeds are small, they are unlikely to be dispersed by the wind, as the plants grow under the forest canopy that blocks strong winds, explains Kenji Suetsugu, the study’s lead author and a professor at Kobe University. .

a Balanophora yuwanensis plant which are red spherical bulbs with small wrinkled bumps.  to the right the plants are eaten
Each round mass of Balanophora yuwanensis looks like a single fruit, however they are made up of several thousand fruits, each measuring approximately 0.3mm in size. The clusters are composed of numerous red bumps that are not the fruits, but rather modified leaves that hide the actual fruits underneath. Yohei Tashiro

The curious role of the Amami rabbit in the propagation of the plant is compounded by the fact that B. yuwanensis it is not an ordinary plant. It has no roots or leaves, and with its dark reddish-brown color it looks more like a strawberry than the traditional leafy shoot. It cannot photosynthesize and as a result acts as a parasite, attaching itself to the roots of other plants to gather nutrients. And it doesn’t produce fleshy fruits, which have bright colors, juicy textures, and distinctive odors that attract seed-dispersing animals looking for a snack. Instead, the parasitic plant produces nuts, but the Amami rabbit still eats them. And after getting its fill of these fruits, the rabbit digs burrows underground where it defecates, which could help place the seeds near the roots of compatible host plants for B. yuwanensis.

The latest findings also illustrate the complex relationship between animals and the services they provide to their environments. “It is likely that rabbits provide a crucial link between [B. yuwanensis] and their hosts,” Suetsugu wrote in an email interview to popular science. “Such natural history observations greatly enhance our understanding of ecosystems.”

Evan Fricke, an ecologist at the University of Maryland who studies seed dispersal, adds that the study highlights the sometimes unexpected roles species play in maintaining the web of life. “I think there is a growing recognition that more plant species depend on animals for seed dispersal than previously thought, even when they don’t have physical structures like pulp to attract fruit-eating animals or hooks to attach to. animal skin. Fricke wrote in a statement to PopSci.

Infrared images from the research team of an Amami rabbit feeding voraciously on a non-photosynthetic plant. Credit: Kenji Suetsugu

Locals have tried to protect the Amami rabbit, which many consider a cultural symbol of the islands, Suetsugu says. In recent years, the rabbit has also been used to promote tourism. But increasing habitat destruction on the Amami Islands has left both the Amami rabbit and the B. yuwanensis endangered plant, says Suetsugu. The government has made some efforts to protect the species from extinction, including hunting down predatory rabbits, mongooses, and bobcats, which have yielded some positive results.

Still, scientists have yet to discover all the services that endangered animals could provide to their ecosystems, Suetsugu says. The decrease in the size of their populations, or their extinction, could significantly affect the functioning of ecosystems.

“Many endangered species have not been comprehensively studied and their full ecological importance may not yet be known,” Suetsugu wrote. “For example, endangered species may play important roles as pollinators, seed dispersers, predators, or prey. They can also help maintain the balance of an ecosystem by controlling the populations of other species.”

[Related: The curious case of an endangered wildcat and a disappearing fruit tree]

Scientists are still trying to understand the roles of endangered animals within their ecosystems, including with seed dispersal, explains Therese Lamperty, a postdoctoral fellow at the University of Washington, in a statement to pop science. The study details a compelling example of pursuing a subtle field observation to make a novel finding, she says.

“Because many endangered animals share common traits, such as large body size, they tend to be species that also perform unique or relatively impactful roles in their ecosystems,” Lamperty wrote. “But because the existing data is limited, we can’t say this for sure and more research is needed.”

Suetsugu says the unknown roles of endangered species need to be taken into account when governments craft conservation policies. Understanding the roles that endangered species play can help conservation managers more effectively protect and restore habitats, control invasive species and reduce other threats, he says.

“Protecting endangered species not only helps preserve biodiversity, but can also have important benefits for human well-being,” says Suetsugu.

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