St Kitts VS Nevis

Observation by Carsyn Bernhardt and Rachel Glendenning

Day 1:

After our failed attempts to have the islands’ species of rodents mate, we begin our first day working along side the Department of Nature and Island Resources in the West Indies to identify and differentiate the rodents. Today is expected to be filled with nothing but the bores of setting up our observation equipment and getting settled. Hopefully by the end of the day we can manage to note a few physical features that will allow us to differentiate the rodents from one another, making it easier to find what the Department has informed us could be a new species of rodent. We will be working as partners throughout this observation, but have decided it will be easier to collect information if we each split up and set up observation sites on both islands, observing the rodents in their separate habitats. It will be far less tedious than taking a boat from island to island every other day…

Day 2:

On the second day here, we observe the rodents and have realized that the average length of hind limbs are quite different. The St. Kitts rodent has the hind limb length of 7.8 cm as the Nevis rodent has the length of 4.2 cm. We are suspicious that something is up due to the abnormal difference in lengths, possibly two different species.

Day 3:

Today we have taken an interest in analyzing the amount of time in which the rodents display courtship. What we have come to currently identify as the Nevis rodent takes much longer, taking an average of 21.3 seconds in their courtship. While the St. Kitts rodent takes only up to 12.6 seconds. We are unsure if this could mean anything just yet, but we have taken the reoccurring difference into mind and our notes.

A Month later:

A month has passed and another red flag has risen to our attention. As the we observe the two rodents more, the more we realized they are different the two are. The one that stayed at St Kitts has observed the rodents completing their gestation time after an average of 29.3 days and now other is waiting for theirs to finish their gestation time in order to compare the two.

Another month later:

We have come to notice a vast difference between the Nevis rodent and St. Kitts rodents’ gestation time. The Nevis rodents’ gestation time continued for approximately 13 days after the St. Kitts’ gestation ceased. This is one of the major behavioral differences between the two rodents that we have come to focus on and it could be the answer to our suspicions.

Conclusion:

We have come to the conclusion that they are both two distant species. After two months we observe their hand limb difference in length we believe due to disruptive natural selections as both are extremes on length, we have come to think that at one time they were the same species and that in order to survive and reproduce they had to go one of the extremes. Then Courtship display changed due to behavioral isolation caused by the two extremes in hind limbs making it impossible to mate with other. Finally gestation time change due to habitat isolation as they become more of distinct species, they each made their own habitat and lived there.

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