What is an example of a reproductive barrier that may separate two similar species?

Answer 1

There are two general categories of reproductive isolating mechanisms: prezygotic, or those that take effect before fertilization, and postzygotic, those that take effect afterward. Prezygotic RIMs prevent the formation of hybrids between members of different populations through ecological, temporal, ethological (behavioral), mechanical, and gametic isolation.

Answer 2

Hybrid inviability and hybrid sterility. In the first the zygote of a mismatched mating does not grow to maturity. This could be many mismatched matings. In the second the zygote grows to maturity but is sterile. Mules are examples of this.

Answer 3

Sterility of hybrids - they do not produce functional gametes eg mules

Hybrids are unfit - die before repoductive age

Some hybrids possess different colour patterns and thus are prezygotically isolated from other individuals.

Answer 4

1. a landslide blocking the valley that the groups used to cross to get to each other
2. a change in number of chromosomes in one group (e.g. human chromosome #1 being the end to end joining of two chromosomes of our last prehuman ancestor, reducing the number of chromosome pairs from 24 to 23) making successful intergroup breeding difficult to impossible even though the two groups may still live together

Answer 5

Hybrid zygotes fail to develop, develop abnormally, or hybrids cannot become established in nature.

Answer 6

Horses and donkeys will readily hybridize, to have mule offspring.

Mules are typically sterile.

Answer 7

In the example of the female horse and male donkey crossing, the offspring is a mule which has the inbred postzygotic barrier that is sterilization, it cannot reproduce.