Interactive investigation: The arthropod story

• Biological evolution accounts for diversity over long periods of time.
• Life forms of the past were in some ways very different from living forms of today, but in other ways very similar.
• Present-day life forms are descended and modified from past life forms; all life is related.
• There is a fit between organisms and their environments, though not always a perfect fit.
• All organisms, including humans, retain evidence of their evolutionary history.
• Fossils provide evidence of past life.
• There are similarities and differences among fossils and living organisms.
• Anatomical similarities of living things reflect common ancestry.
• Traits that are advantageous often persist in a population.
• Scientists use anatomical features to infer the relatedness of taxa.
• Classification is based on evolutionary relationships.
• Evolutionary relationships may be explored on branching cladograms.

• Classification/Phylogenetics
• Evidence for Evolution
• History of Life