Final answer:
A phylogeny describes the evolutionary history and relationships between species, using diagrams called phylogenetic trees which illustrate ancestral relationships and divergence events. Phylogenetics helps map the tree of life and is a core concept in systematics.
Step-by-step explanation:
A phylogeny is a description of the evolutionary history and the relationships among a species or group of species. The study of phylogeny falls under the branch of biology known as systematics, which involves organizing and classifying organisms based on their evolutionary relationships. Phylogenetic trees, which are diagrammatic representations of such relationships, are composed of nodes and branches, where the internal nodes represent ancestors at points of divergence leading to the formation of new species.
The length of each branch on a phylogenetic tree is proportional to the time elapsed since the split, making these diagrams a visual summary of life's evolution on Earth. Phylogenetic trees are built using a variety of data including DNA sequence alignments and are considered hypotheses of an organism's evolutionary past. Phylogenetics does not only concern with the similarities and differences in genetic or physical traits but also focuses on the understanding of shared ancestry and the relative times in the past that species shared common ancestors.
Therefore, phylogenetic relationships refer to not merely the characteristics organisms share or differ in but extend to the broader context of evolutionary lineage and descent, mapping out the tree of life that connects all living beings back to common ancestors.