All the populations living and interacting within a particular geographic area make up a biological (or biotic) community. The living organisms in a community together with their nonliving or abiotic environment make up an ecosystem.
A reason could be the bodies ability to process the water based vitamin as well as the person's diet. many things have b12 in it but choosing to cut something out, like meat, could cause a deficiency
Answer:
When a long-term environmental change occurs, certain individuals in a population will be better adapted for the new environment than others. ... Over many generations, these favorable adaptations build up in a population. This may lead to speciation, which is the development of a new species.
