temporal isolation which causes the two populations of one species are isolated this way, they no longer reproduce with each other due to differences in mating times, ecological isolation which implies reproductive isolation of populations inhabiting separate niches as a result of divergent selection of ecologically influenced characters, and behavioral isolation which occurs when populations of the same species begin to develop different behaviors that are not recognized or preferred by members in another population.
A duck billed platypus is classified as a mammal because it feeds its kids with milk and it has fur. They are very unsual because of the way they dig dirt burrows at the water's edge and how they dont have a stomach