Why should we even care about plant evolution (and other mysteries)?

Throughout this semester and last, during which I studied plant evolution and phylogenies in island environments, I have been asked the question, “So, why are you doing this? Like, what is so special about a plant?” I would ponder over this question myself, and finally came to the conclusion of why plants are so important to understanding the history of the evolution of all life-forms. Though animals may seem more exciting to study because they move and eat and make noises, they would not be alive without the vast diversity of plants that have been able to adapt to the different environments on this earth - animals have only been able to adapt to life on earth because of the migration of plants from water to land and their adaptations. But most intriguing for evolutionary studies is the evolution of plant species in island or island-like environments (that includes montane regions).

This semester I am studying the evolution of Scalesia on the Galapagos islands. According to previous studies, Scalesia is part of the Heliantheae genus and is a sister clade to the Viguiera subspecies. Viguiera originated from the Peruvian Andes and relates perfectly to my previous ELI subject, the evolution of Lupine species in the Peruvian Andes at extreme elevations. Apparently, during the late Pleistocene, a land bridge formed between North and South America, which allowed for the transfer of Viguiera to the Galapagos islands as well.

Some of the background I have needed to understand my reading about previous research done on the Galapagos involves data analysis methods such as Bayesian Inference, Maximum Likelihood, and Maximum Parsimony. Maximum Likelihood and Bayesian Inference are very similar - they describe the statistical probability that a character (a trait) may change from one state (for example, from a cytosine to a guanine) in a population by using statistical algorithms that nowadays are mostly calculated by nifty computer programs.

The fact that one can infer the tree phylogeny of several species in a genus from observing the rate of change of character states seemed intriguing to me, and it made me wonder if there was any chemistry involved in the process. Throughout the year I have been taking AP Chemistry online and had relatively recently learned about the rate of reaction in a chemical system at different states (such as equilibrium state, increased pressure or volume, or other environmental stresses that may affect entropy and enthalpy which in turn affect Gibbs Free energy). I wondered if perhaps the probability of the rate of change between different nucleotides in a DNA sequence in a species could be related to the rate of reaction of that change, which was affected by the outside environment, in which the species were situated due to epigenetic markers that were involved in the chemical reaction (as catalysts, buffers, or other).  I felt like this understanding would allow people to better understand why evolution occurs in a population and would allow us to prevent harmful viruses and bacteria spreading.

These thoughts have been floating around in the swirling chasms of my brain, and I hope they interest you too.

~Valeria