: The most basic unit, defined as a group of organisms that can interbreed to produce fertile offspring.
A biological group refers to any assembly of plants or animals categorized by shared characteristics. These groups are primarily defined by three key features: they are , hierarchically nested , and congruent across different data sets . Key Features of Biological Groups
: This is often considered the most distinctive feature. It means that groupings based on one set of characters (like physical morphology) typically align perfectly with those based on another (like DNA sequences).