AP BIOLOGY

Detailed explanation-1: -Postzygotic barriers include the creation of hybrid individuals that do not survive past the embryonic stages ( hybrid inviability ) or the creation of a hybrid that is sterile and unable to produce offspring ( hybrid sterility ).

Detailed explanation-2: -Under this concept, two interbreeding taxa (populations) are conspecific, if they produce fertile hybrids and allospecific, if they fail to produce zygotes (prezygotic sterility barrier) or their hybrids are infertile (postzygotic sterility barrier).

Detailed explanation-3: -Answer and Explanation: A post-zygotic barrier occurs when two individuals mate but either fail to produce offspring or produce offspring that are not fertile.

Detailed explanation-4: -Hybrid inviability is a post-zygotic barrier, which reduces a hybrid’s capacity to mature into a healthy, fit adult. The relatively low health of these hybrids relative to pure-breed individuals prevents gene flow between species.

Detailed explanation-5: -Hybrid sterility is the most prevalent form of postzygotic RI in the plant and animal kingdoms (Ouyang et al., 2010; Rieseberg and Blackman, 2010; Maheshwari and Barbash, 2011). The hybrids develop vitally at the vegetative stage, whereas sterility appears in either the F1 or F2 generation.