1. Physical characteristics: This includes features like body shape, size, structure, and the presence or absence of specific organs. For example, mammals are classified by their fur, mammary glands, and warm-bloodedness.
2. Genetic relationships: Biologists analyze DNA sequences to determine how closely related different organisms are. This is a powerful tool for understanding evolutionary history and clarifying relationships between species.
3. Evolutionary history: This considers the lineage of an organism and its relationships to other organisms. This can be inferred through fossil records and the analysis of shared characteristics.
These three factors work together to create a robust and meaningful classification system that reflects the diversity and interconnectedness of life on Earth.
