Question

Consider the reproductive isolating mechanisms described above. Do any of these apply to human beings? Write a few paragraphs in your notebook on this topic.

Answer 1

A reproductive isolating mechanism is a trait that prevents members of different species from reproducing. The mechanism can be structural, functional or behavioral. These mechanisms are divided into two categories: pre-mating types and post-mating types.

Pre-mating isolating mechanisms are differences in body structure, behavior or location that prevent two species from mating. Differences in reproductive anatomy or other body parts are a type of mechanical isolation that prevents mating between species. Differences in behavior can include differences in mating rituals. When two species occupy different habitats, they are less likely to meet and to attempt to reproduce. This is called habitat isolation. Temporal isolation occurs when two species live in the same location, but each reproduces at a different time of the year. This prevents gene flow between the populations.

Post-mating isolating mechanisms are caused by developmental or physiological differences between the members of two species. The gametes of two different species may not be compatible. If the gametes lack receptors to promote fusion, they cannot form a zygote. Another example is an egg that has receptors only for the sperm of its own species. Zygote mortality is the mechanism at work when hybrids do not live to reproduce. (Hybrids are offspring of parents of two different species.) In some cases, hybrid offspring are produced but they remain sterile. Mules are sterile hybrids that result from the mating of a horse and a donkey.

Answer 2

@Compassionate @zepdrix can you help please

Answer 3

@mazmaz