Mutualism without Continuous Contact 



373 



which these wasps can lay their eggs. A simihir dually obligate and 

 specific symbiosis is found in the relation between the yucca plant 

 and the yucca moth (Fig. 10.6). The female moth visits the yucca 

 flower in the evening and collects a ball of pollen from the anthers. 

 Then, holding the pollen ball in specially adapted mouth parts, she 

 flies to another plant and pierces the ovary of the flower with her 



Fig. 10.6. The Yucca moth (Promiba ijuccaseUa) approaching flower of the 



yucca plant (left). Flower cut open (right), showing the moth placing pollen on 



the stigma. ( Modified from Borradaile, 1923. ) 



ovipositor. After depositing eggs within one of the ovules, the moth 

 creeps down the style and stuffs the ball of pollen into the stigma. 

 When the moth eggs hatch, the larvae feed on the tissue of the ovule, 

 and eventually mature to repeat the process for the next generation. 

 It is difficult to imagine in such complex interdependencies how the 

 behavior pattern and anatomical structures vitally necessary to both 

 species have evolved. 



Other two-way benefits in the relations between species involve 

 transport and dispersal of seed. The fruit eaten by birds, mammals, 

 and other animals provides them with a source of nourishment, and 

 the contained seeds are subsequently dropped in their excrement at 

 varying distances from the original site. The activity of squirrels in 

 carrying and burying acorns, hickory nuts, and the like may play a 



