Final answer:
Molecular systematics uses DNA technology to understand phylogenetic relationships among organisms, forming a basis for the classification within a taxonomic system. It compares molecular sequences, like amino acids and nucleotides, to find evolutionary divergences and assumes that more similar sequences imply closer relationships.
Step-by-step explanation:
The study of molecular sequences has vastly improved with the advancement of DNA technology, leading to a field known as molecular systematics. This technique makes use of molecular evidence, such as DNA sequencing, to identify phylogenetic relationships among organisms. The primary goal is to construct a phylogenetic tree that illustrates these relationships, displaying patterns of ancestry and descent.
A monophyletic group or clade consists of organisms that share a single ancestor. The classification of these groups falls into a taxonomic system, with divisions like domain, kingdom, phylum, class, order, family, genus, and species. Cladistics is the method that organizes homologous traits to describe phylogenies using common descent as the main criterion for classifying organisms.
Molecular comparisons reveal evolutionary relationships by analyzing the similarities in sequences of amino acids in proteins or nucleotide bases in nucleic acids. Through time, the more differences accumulate in these sequences, the longer it is since their evolutionary paths diverged. Genes evolving at different rates affect their usefulness in determining relationships, with slowly evolving sequences being more suitable for distantly related species. Essential to this field is the concept of maximum parsimony, which favors the simplest explanation or pathway with the fewest steps.