EPOW - Ecology Picture of the Week

The Wolf and the Nightshade

Wolf Apple (Solanum lycocarpum), Family Solanaceae
Yucatan Peninsula, Mexico

Explanation:  This is the strange story of a carnivore and a plant.  

I encountered this beautiful bloom during an exploration of the ancient Mayan citadel Dzibilchaltun on the Yucatan Peninsula.  The tree to which it was attached is variously called wolf apple, or, in Portuguese, lobeira ("wolf's plant"), or fruta-do-lobo ("fruit of the wolf").  

Why Portuguese?  Because this plant's native range is mostly in the savannah of Brazil where Portuguese is spoken.  This plant had likely been introduced to the Yucatan from that region, although why it was growing among the ruins of an ancient Mayan temple, and exactly when it was introduced here, is unanswered.  Perhaps it might have something to do with its fruit being used in folk medicine, such as for treating diabetes and obesity and to reduce levels of cholesterol.

Wolf apple belongs to the nightshade family which includes many vital agricultural crops but also fatally toxic plants bearing high concentrations of alkaloids.  And so wolf apple had been blamed -- unduly so -- in the cerrado (savannah) of Brazil for killing livestock that ate its fruits.

Enter now the maned wolf (Chrysocyon brachyurus), a nearly-threatened carnivore endemic to the cerrado of central South America.  One primary food item of the maned wolf is ... you guessed it, fruit of the wolf apple tree.  

In fact, seeds of wolf apple fruits are consistently found in the wolf's scat (faeces) year-round.

Moreover, studies have demonstrated that wolf apple seeds germinate and grow significantly faster and with higher viability after they have passed through the wolf's digestive tract.  And the fruit is too large to disperse by most any other means, so the wolf also acts as a key dispersal agent for the plant.  

So the wolf may be key to the viability of the wolf apple tree, and the tree's fruit may be key to the wolf's survival.

Wait, it gets weirder.

Wolf apple plants are also found to grow from the mounds of leaf-cutter ants.  And the ants clear the top of the mounds of all other vegetation that might compete with the wolf apple plants.  And ... the ants would take wolf apple seeds and wolf scat into their burrows, where most of the seeds would germinate, using the faeces as fertilizer.  

So what do the ants get out of all this?  Well, the wolf's faeces also help to fertilize the ants' underground fungus gardens, which the ants use ... well, check out this part of the story yourself.

Life is amazing!  Wolf, fruit, ant, fungus, faeces, seeds, burrows ... all intricately tied in wonderful and unexpected ways.  Little did I suspect this when I stumbled upon the beautiful bloom that hot summer day so long ago, in the shadow of an ancient Meso-American civilization ...