What concept in biology describes a gradual change in a species over time?

The concept that describes a gradual change in a species over time is evolution. Evolution refers to the process by which species undergo changes in their genetic makeup across generations, often as a result of natural selection, environmental factors, and genetic variation. This ongoing process leads to the adaptation of organisms to their environments and can result in the emergence of new species over long periods.

Understanding evolution is fundamental to biological sciences because it explains the diversity of life and the relationships between different organisms. Natural selection, adaptation, and mutation are all mechanisms that contribute to the evolutionary process but do not fully encapsulate the broader concept of gradual changes in species over time. Evolution encompasses the cumulative effects of these mechanisms, shaping the biological landscape as species adapt, change, and may even diverge into new forms.