Why is population structure important?

The date for my dissertation defense is approaching fast. A couple of months or so and I will be seating in front of my committee.

While reviewing the work I have been doing for the past 5 years I realized that intuitively simple things could be the toughest to explain to a committee of PhDs.

For example, in my dissertation I talk a lot about population structure in different species of endangered iguanas. The concept of population structure is intuitively very simple to grasp. That is why I never spent too much time in formalizing an answer to the potential question “Why is population structure important?” (and I am glad to know that I am not the only one who struggled with this, see here).

To anticipate any “debacle” during my defense I decided to write a short post on why I thing population structure is such an important concept, worthwhile to study and understand clearly. Here it goes.

Studying biological evolution is basically to study the processes of cumulative changes (morphological changes, genetic changes, behavior changes etc. etc.) happening in any group of  living beings. Biologists and researchers recognize that evolutionary cumulative changes are not uniformly distributed across all individuals within a species. Rather different processes will affect individuals accordingly to their spatial and/or temporal organization. Finding ways to describe the structure of individuals within species, then, becomes important to better understand what kind of changes (genetic drift rather than selection and such…) are going to play a role in shaping their evolution. Eventually, this information is not only used to better understand evolutionary processes, but also to inform conservation strategies and make meaningful predictions about the overall survival of populations.

As aforementioned, (and as I hopefully managed to explain) the concept of population structure is simple to grasp. A way more complicated endeavor is finding a clustering algorithm that could accurately represent shared evolutionary history among clustered individuals. Unfortunately, despite the many advancements and the many algorithms developed, finding a “one ring to rule them all” kind of deal is rather complicated if not impossible (very much like it is difficult to find a species definition that applies to all organisms). And I will try to address this issue in the next post.

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