Animals and plants have one of the most ideal relationships in nature. The plants feed the animals and the animals, in turn, spread the seeds of the plants through their excrement. But when tree-climbing goats in southern Morocco eat the fruit of the argan tree, the seed is spread in more-or-less the opposite way, says new research out of the Ecological Society of America.
The process by which an animal passes a plant's seed through its digestive system and out through its feces is called endozoochory, and it happens thousands of times a day all across the globe. But the Moroccan tree-climbing goats don't usually excrete large seeds such as those found at the center of the argan fruits they sometimes climb 30 feet in the air to get.
Instead, they first digest the fruit in a specialized stomach. Then, they regurgitate the contents, like cows, and chew the cud. During this process, the researchers discovered, the goats spit out the seeds, transporting them across the land and giving new argan trees a chance to grow. Through laboratory testing they found that over 70 percent of the seeds were still viable after this process.
The goats spend about three-quarters of their time in the autumn – when fallen fruit and other food sources become scarce – foraging in the treetops. Local herders even teach young goats how to ascend into the trees, which the herders prune for easier access.
The researchers say that the finding is significant in understanding how ruminants like goats could be playing a key role in helping plants spread. Seeds can remain in the animals' rumens (specialized stomachs for fermenting food before it is regurgitated) for up to several days so that fact, combined with the sometimes wide-ranging foraging habits of ruminants, means that seeds can be dispersed over hundreds of miles.
While much research has been conducted regarding the spreading of seeds through the feces of ruminants, the authors say more needs to be done to take into account the action of seed spitting.
The research has been published in Frontiers in Ecology and the Environment.
Source: Ecological Society of America