Need a specific prezygotic and postzygotic barrier that can

Need a specific prezygotic and postzygotic barrier that can be tested through an experiment and describe which barrier would be stronger

4) As mentioned (briefly) in class, California has the highest diversity of chipmunks (Tamias) of anywhere in the world with 13 of the 25 total species. Two species that co-occur in the mountains in southern Kern County are the Merriam\'s Chipmunk (Tamias merriami) and the California Chipmunk (Tamias obscurus). These species are sister taxa and are known to occasionally hybridize. In a well-constructed essay, describe how you could experimentally determine the strength of one prezygotic and one postzygotic isolating barrier between these two species. Additionally, describe your prediction for which of these two barriers will be stronger if reinforcement is taking place and why you have this prediction. You will be graded on content, writing style (grammar, word choice, sentence construction), and organization (logical flow, clear topic and concluding sentences). You can neatly hand-write in the space below or attach a typed answer to the end of this assignment.

Solution

As we know that different species can\'t interbreed, produce fertile offsprings. This is due to prezygotic and postzygotic isolation barriers.

Prezygotic isolation can be of following types:

1. Behavioral : different species have different mating rituals so they might not be interested in copulating.

2. Temporal : species might have different seasons for mating.

3. Gametic: for fertilization to occur it is necessary that gametes recognise each other and different species have different chemical composition of their gametes, so theirs a probability that gametes doesn\'t recognise each other.

On the other hand if fertilization takes place postzygotic isolation barriers are there in order to preserve speciation.

Postzygotic isolation occurs in following ways:

1. Hybrid inviablity: hybrid dies prematurely or hybrid zygote hasn\'t developed fully.

2. Hybrid sterility: Hybrid develops into a viable healthy offspring but can\'t reproduce because of lack of certain chromosome or part of it. Mule is best example of hybrid sterility. It is hybrid of horse and donkey and a sterile hybrid.

3. Hybrid breakdown: Hybrid develops into healthy fertile offspring but they disappear with time as from one generation to other they become weaker and less fertile.

In my opinion postzygotic barriers are more stronger as nature itself selects survival of fittest here by allowing sterile or inviablity hybrid s to develop. Also no matter how hard one can try cases can be seen that prezygotic barriers can be crossed every now and then. As our case in question shows that two chipmunk species are living in same habitat, so we can go for their behavioral, temporal study for prezygotic barrier and if mating occurs and hybrid develops we get a chance to study postzygotic barriers of nature.