Gene pool
Sum of a population's genetic material at a given time. 
The term typically is used in reference to a population made up of individuals of the same species and includes all genes and combinations of genes (sum of the alleles) in the population.
        
             
        
        
        
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Explanation:
a transform fault boundary is formed. 
 
        
             
        
        
        
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Environmental pressures
Basically every animal adapts to pressures from their environment in different ways, causing them to have different shapes and sizes
 
        
             
        
        
        
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B.soil that is frozen solid all year
C.summer thaws combined with frozen permafrost
D.the overflow of a large lake each summer