Confusing Variation or Incipient Species?

This fall I was glad to have another opportunity to work with Dr. Brokaw in the research lab. This year we researched the genus Mentzelia, a group including several American flowering plants. Having worked with animal DNA in previous semesters, I was glad I got the chance to study plant life and broaden my experience. I learned how to extract DNA from Mentzelia leaves in a process that involved crushing them up with a pestle and centrifuging them while treating it with different washes before and in between intervals of the spinning. I was prepared well for other procedures involved after that process, such as prepping the DNA for the PCR from my research sessions with Dr. Brokaw and other research students where we took a closer look at DNA from the rodent genus Thomasomys

I saw parallels between the two projects, not only in that similar methods were used, but because for the Thomasomys research we had extracted DNA from the mitochondria of the animals, and this semester we took our Mentzelia DNA from the chloroplast, which is believed to have a similar origin to the mitochondria. This semester our results were not as conclusive as we had hoped they would be, so we could not prepare a poster; however, this means there is opportunity for research to be continued in this area by future groups. 

That being said, there were some findings and interesting observations that took place. For instance, we saw that species M. gracilenta bears a strong (almost indistinguishable) resemblance to M. pectinata, but since we were able to count their chromosomes, we could tell the two apart. Likewise, we observed that there are differences between the northern and southern populations of M. gracilenta and that these variants may well be separate species and even play different roles in their respective ecologies. As Dr. Brokaw put it, “I guess we still do not fully understand species boundaries (if they exist) between some of these things.” 

Another thing that caught our interest was that some of the samples of M. lindleyi were found in vertic clay and with orange petals; both of these are atypical for the species. We believe this might be an example of incipient speciation (which many forget still happens today) or that these samples might be a hybrid of M. lindleyi with another plant. On a related note, we found that both M. lindleyi and M. gracilenta samples collected in the Griswold Hills – Ciervo Hills region were unlike the more standard examples of their respective species and that the climate they were growing in was abnormal as well. Another thing to consider was that there is likely cross-breeding going on between the different Mentzelia species in these areas, which makes distinguishing between the different types and defining what exactly is characteristic of an individual species difficult. Further research is needed to give us more clarity on the subject.

This entry was posted in Brokaw Lab and tagged , . Bookmark the permalink.

Leave a Reply