In order for speciation to occur organisms can no
longer interbreed. this is known as

reproductive isolation
physical isolation

Reproductive isolation

Explanation:

The definition of speciation is "the formation of new and distinct species in the course of evolution." Because a new a distinct species is formed, even if not physically isolated, they can not interbreed because two species can not reproduce with each other. Therefore, the answer is Reproductive isolation, because speciation will still occur even without physical isolation.

reproductive isolation

Explanation:

did it on edgnuity

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.