The process of evolution drives the diversity and unity of life.EU 1A – Change in the genetic makeup of a population over time is evolution. 1. Natural selection is a major mechanism of evolution. 2. Natural selections acts on phenotypic variations in populations. 3. Evolutionary change is also driven by random processes. 4. Biological evolution is supported by scientific evidence from many disciplines, including mathematics.EU 1B – Organisms are linked by lines of descent from common ancestry. 1. Organisms share many conserved core processes and features that evolved and are widely distributed among organisms today. 2. Phylogenic trees and cladograms are graphical representations of evolutionary history that can be tested.EU 1C – Life continues to evolve within a changing environment. 1. Speciation and extinction have occurred through the Earth’s history. 2. Speciation may occur when two populations become reproductively isolated from each other. 3. Populations of organisms continue to evolve.EU 1D – the origin of living systems is explained by natural processes. 1. There are several hypotheses about the natural origin of life on Earth, each with supporting scientific evidence. 2. Scientific evidence from many different disciplines supports models of the origin of life.