Blog 4: Lobo and Blanco

Hello everyone, and welcome back to my blog! As you all know by now, the purpose of my research is to use NIR spectra to discriminate between species of protium (Burseraceae) and to create a model that can quickly identify species from spectra alone. Given the difficulty of this task, I began my project with fairly low expectations regarding the success of my discriminating algorithm, but today, I will be sharing one of the more exciting success stories from this project to date: species discrimination! Over the course of the last few weeks, I’ve scanned and analyzed countless species, but my focus remained on a particular cryptic species that Dr. Fine told me to investigate: Protium subserratum. This species complex is currently considered to be a single, incredibly common species of native tree in the Amazon, and it is found in nearly every corner of the jungle.

From my analysis of the spectra my team collected of Protium subserratum, Dr. Fine and I have concluded that Protium subserratum is, in fact, two separate species that we have denoted as lobo and blanco. 

Although my LDA analysis and discriminating algorithm have not yet been validated for other species and species complexes, the differences in spectra between lobo and blanco are so apparent that they can be seen and identified with the naked eye. Because of this, my analysis of this species complex’s spectra only relied on the absolute basics. Using the datasheet below, I averaged an individual’s readings into one “individual signature” and then compiled those signatures into a broader “species signature.” Once those steps were coded and completed, it was immediately obvious by comparing the signatures of lobo and blanco how different the two species were. 

Layered readings for blanco are displayed on the left, and readings for lobo are displayed on the right. From these graphs, it is apparent that Protium subserratum features two distinct spectral groups.

Lobo and Blanco are, however, incredibly rare cases. Although it is amazing when it occurs, the spectra from two species of protium (Burseraceae) can almost never be differentiated with the naked eye, much less spectra from one species complex. Since my initial identification, Lobo and Blanco have remained the only two species of protium (Burseraceae) that I can identify without the use of a computer algorithm. Because of this issue, the question becomes how to differentiate graphs of species that can not be seen so easily. To which, the answer that I will cover in my next blog is LDA (Linear Discriminant Analysis). I hope you’ve enjoyed reading about this taxonomical development in the species of Protium subserratum, and I hope that you’ll stick around until next week to learn about LDA and how I’ve implemented it in my project. Thank you for reading!