Answer:
The answer is carrying capacity
 
        
                    
             
        
        
        
Gradual changes in the frequency of diseases over long periods are known as SECULAR TIME TRENDS. For example, the rate of mortality in USA due to coronary heart diseases over a period of time. Onset of puberty in girls is also a secular time trend. 
Secular time trend is also referred as Secular Variation and Secular Drift. 
        
             
        
        
        
Answer:
answer is shown and pictured