Introduction to Biology Pt. 3: The Phylogenetic Species Concept

Introduction to Biology Pt. 3: The Phylogenetic Species Concept

When studying the life sciences, there are a lot of in-depth concepts to take in. Depending on the the type of science you are studying, biology vs. evolution, for example, you may even have to learn a handful of mathematical formulas to fully appreciate the material. Here, we are just having a light-hearted overview of the life sciences, so a light serving of sativa will do just fine.

In my experience, sativa helps me to not get lost in wordy texts (reading that is not broken up by graphics/tables or formulas) and keep my mind sharp and able to take in all relevant information. Grinding about 60mg (less than 1/4 of a 1g bud) of sativa and smoking just a small pinch of that for over a 3-5hr period is perfect for maintaining a healthy attention span for learning.

Black Flower Science Co. does not claim to be a medical professional and does not offer recommendations as a substitute for medical advice. All advice and recommendations are based on personal experience of the benefits of medical marijuana. If you are experiencing severe or declining mental health symptoms, please seek the advice of a medical professional.

The biological species concept was one of the earliest attempts in defining the qualifications to be a species and at some point was widely recognized. It defined species as interbreeding members of a population that produce viable offspring, however this excluded many organisms.

The phylogenetic species concept improved this definition by combining the interbreeding idea from the biological species concept with evolutionary history.

This article explores the way a species is defined through the phylogenetic species concept in greater detail. It will also go into the role of evolutionary history in identifying a species.

The tree of life

There is biological evidence that all organisms since the very existence of life are genetically related. The histories of their lineage, phylogeny, are represented by the tree of life.

This idea became popularized by the father of evolution, Charles Darwin. He suggested that every species arose from an earlier form and that all of them can be traced to a single common ancestor.  

Since the release of Darwin’s book On the Origin of Species, many attempts were made to portray the evolutionary relationships of known species at the time.

This became an easier task through phylogenetic systematics, a method of reconstructing evolutionary history. Ways this is often done in modern research is by matching the DNA sequences of different species and tracing their relationship to a common ancestor. 

Photo by Stephanie Klepacki on Unsplash

Amending the biological species concept

The phylogenetic species concept recognizes the way history participates in generating species. All organisms (including both sexually and asexually reproducing species and hybrids) are traced to a common ancestor.

Questions such as what natural causes resulted in them to diverge into separate groups may be explored, creating a deeper knowledge about their origin. 

In further understanding history, the phylogenetic species concept also allows scientists to easily classify fossil records. This concept is an especially better approach in paleontology, since reproduction cannot be observed in extinct animals such as dinosaurs and neanderthals.

Not only is it better in identifying fossils, all populations in general do not have to be observed for interbreeding as this can be difficult to keep up with in certain species. 

Limitations to the phylogenetic species concept

While the phylogenetic species concept is stronger than the biological species concept,  it is not without flaws. Researchers often argue about how irreducible of a cluster a species is.

This concept is not clear on how small the species can be divided, making it possible to create even smaller groups from the slightest variation. 

This becomes problematic when there are too many species recognized, as it can be misleading when studying biological topics such as biodiversity.

Additionally, all organisms have a common ancestor throughout evolutionary history, raising the question of how recent the common ancestor can be when forming a monophyletic group. 

Is the phylogenetic species concept enough?

With its list of weaknesses, the phylogenetic species concept cannot possibly be enough to satisfy all researchers. It does however provide a better foundation than the biological species concept to start with. Ad hoc alterations can be made as more limitations are discovered, to work towards an even better species concept.

References

Zelnio, K. (2012, April 20). Species Concepts. Retrieved from https://blogs.scientificamerican.com/evo-eco-lab/species-concepts/

Wheeler, Q. D. (1999). Why the phylogenetic species concept?—Elementary. Journal of nematology, 31(2), 134. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2620362/pdf/134.pdf 


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