Answer:
Because natural selection acts directly only on phenotypes, more genetic variation within a population usually enables more phenotypic variation. Some new alleles increase an organism's ability to survive and reproduce, which then ensures the survival of the allele in the population.
Explanation:
hope this is right...
Answer:
Contract; relax
Explanation:
In the patellar tendon reflex arc, the quadriceps femoris contracts when the quadriceps femoris of the the thigh is stretched through the stretching of the patellar ligament. This also causes the hamstring to relax
The answer would be population
No the environment was alredythere beforee wilderbeasts even existed