<span>A: The proportions of a population that are at different age levels make up the population’s age structure. </span>
        
             
        
        
        
Answer:speciation
Explanation: Speciation is the evolutionary process by which populations evolve to become distinct species. There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another these are allopatric, peripatric, parapatric, and sympatric. Speciation may also be induced artificially, through animal husbandry, agriculture, or laboratory experiments.
 
        
             
        
        
        
        
I think the relationship is Commensalism ( relationship between two organisms in which one benefits and the other does not benefit nor is harmed ) because the bird benefits and the cow does not benefit nor is harmed. Hope this helped ☺