List the barriers that prevent interbreeding, and give an example of each.

Prezygotic barriers are mechanisms that prevent mating or fertilization between different species. They operate before the formation of a zygote. Here are some examples: 1. Temporal isolation: When species breed at different times of the day, season, or year. For example, some species of frogs breed in the spring, while others breed in the fall, preventing interbreeding. 2. Habitat isolation: When species occupy different habitats, even within the same geographic area, and rarely encounter one another. For example, aquatic and terrestrial species of snails usually do not interbreed. 3. Behavioral isolation: When species have different courtship rituals or signals that prevent mating between them. For example, distinct bird songs act as a barrier between different bird species. 4. Mechanical isolation: When species have incompatible reproductive structures that prevent successful mating. For example, differences in flower shape can prevent pollinators from transferring pollen between plant species. 5. Gametic isolation: When sperm from one species cannot fertilize the eggs of another species. For example, sea urchins release their sperm and eggs into the water, but the sperm can only fertilize eggs of the same species.

Postzygotic barriers are mechanisms that prevent the formation of viable, fertile offspring after the formation of a zygote. They operate after fertilization. Here are some examples: 1. Reduced hybrid viability: When the hybrid offspring have reduced chance of survival. For example, some salamander crosses can produce embryos, but they have a high mortality rate. 2. Reduced hybrid fertility: When the hybrid offspring cannot produce viable gametes. For example, a mule, which is a hybrid between a horse and a donkey, is sterile and cannot produce offspring. 3. Hybrid breakdown: When the offspring of hybrids have reduced fitness or complete sterility. For example, when two different strains of rice are crossed, the resulting hybrid is fertile, but its offspring are often sterile or have reduced vigor, preventing further interbreeding between the strains.