Na reflex arc, the sensory neurons are neurons, while the motor neurons are neurons

In a relfex arc, the sensory neurons are also known as afferent neurons, while the motor neurons are known as efferent neurons. Afferent neurons because they bring in the signal from the sensory organs or sensory receptors to the brain. The neurons that carry information from the brain or the spinal cord to the muscles for making a movement are called efferent neurons.

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.