There are often not more than one or two independent variables tested in an experiment, otherwise it is difficult to determine the influence of each upon the final results. There may be several dependent variables, because manipulating the independent variable can influence many different things.
        
                    
             
        
        
        
There’s less scarcity of food for the population is an advantage of a single population of animals having a large amount of variability surrounding certain traits 
<u>Explanation:</u>
The population of animal is eating three different types of plants. One of them is good in digesting plant A, one of them is good in digesting plant B and other group is good in digesting plant C.  
Thus, the population although has a huge number, but each of the individual is divided into one of the 3 groups which is different in feeding habits. Thus there’s no scarcity of food in the population. Thus the population can live well and reproduce without any nutritional strain.  
 
        
                    
             
        
        
        
The word you're looking for is the Bowen's reaction.
Hope it helped!
        
             
        
        
        
Harweda cares for the bird and begins thinking about its comfort as well as his own.