The first unit of Advanced Biological Systems is focused on the theory of evolution, the mechanisms of evolutionary change, and discussions of the biological species concept. We discuss briefly how biodiversity stabilizes ecosystems. A study of biological evolution is placed first in the sequence of our curriculum to establish a foundation that explains the diversity of organisms, as well as biochemical processes, and the ongoing change process we witness today. These concepts will later be utilized in our curriculum to highlight cellular and metabolic diversity, the development of cancers, the interactions of bacteria with the ecosystem of the human host, and society’s creation of a human-engineered ecosystem.

We start with student research and presentation on the various eras in Earth’ history to establish a recognition that change has always occurred and is correlated with environmental changes. This is followed quickly by having students examine the evidentiary supports for the evolution of species from common ancestry. The samples under study run from models of fossil specimens, whole or parts of contemporary organisms, and protein and nucleic acid sequences. After evidence for evolution is provided, the mechanisms that drive biological evolution are discussed. Special attention is given to genetic drift and bottle neck effects to emphasize the roots of these changes found in random inheritance of traits, but also to highlight the outsized effects these mechanisms have on small populations. The unit ends with discussion on the biological species concept and the biological value of biodiversity. To support this discussion, we develop a considerable focus on reading primary literature.