What evolutionary concept explains the gradual development of species over time?

The correct choice is macroevolution, which refers to the processes that lead to the gradual development and diversity of species over long periods of geological time. Macroevolution encompasses a range of evolutionary changes, including the emergence of new species, the extinction of others, and the major transitions in the history of life, such as the development of multicellular organisms from ancestral forms.

This concept highlights the large-scale patterns and trends in evolutionary biology and is often contrasted with microevolution, which focuses on smaller-scale changes within species, such as variations in gene frequencies from one generation to the next. While microevolution examines how populations evolve and adapt over short time scales, macroevolution provides a broader perspective on how these changes accumulate and can lead to significant shifts in the diversity of life over millions of years.

Speciation, another evolutionary process, is the culmination of macroevolution as it explains how new species arise from existing ones. Extinction, while a significant aspect of evolutionary history, refers to the loss of species rather than their gradual development. Thus, macroevolution captures the overall framework through which species evolve, adapt, and diversify over extensive periods.