Final answer:
Types of barriers contributing to reproductive isolation after hybrid zygote formation include postzygotic barriers like hybrid inviability, where hybrids do not survive embryonic stages, and hybrid sterility, where hybrids are unable to reproduce.
Step-by-step explanation:
The question asks about the types of barriers that contribute to reproductive isolation after the formation of a hybrid zygote. In biology, reproductive isolation mechanisms are categorized into prezygotic barriers and postzygotic barriers. Once fertilization takes place and a zygote forms, postzygotic barriers come into play which can prevent the hybrid from successfully contributing to the gene pool.
Hybrid inviability is one such postzygotic barrier where hybrid embryos fail to develop properly or do not survive past the embryonic stages. Another crucial postzygotic barrier is hybrid sterility, where hybrids may grow to adulthood but are unable to reproduce, as seen with mules (horse-donkey hybrids). These postzygotic barriers are essential in maintaining species boundaries and contributing to the process of speciation.