26.1: Introduction

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Phylogenetics is the study of relationships among a set of objects having a common origin, based on the knowledge of the individual traits of the objects. Such objects may be species, genes, or languages, and their corresponding traits may be morphological characteristics, sequences, words etc. In all these examples the objects under study change gradually with time and diverge from common origins to present day objects.

In Biology, phylogenetics is particularly relevant because all biological species happen to be descendants of a single common ancestor which existed approximately 3.5 to 3.8 billion years ago. Throughout the passage of time, genetic variation, isolation and selection have created the great variety of species that we observe today. Not just speciation however, but extinction has also played a key role in shaping the biosphere as we see today. Studying the ancestry between di↵erent species is fundamentally important to biology because they shed much light in understanding di↵erent biological functions, genetic mechanisms as well as the process of evolution itself.