Life’s diversity is shaped by evolutionary forces acting across populations, species and ecosystems. Volume 2 covers evolution, phylogeny, organismal biology and comparative physiology across plants, animals and microbes. Chapters integrate ecology, adaptation and developmental biology to explain organismal form and function. Field and lab exercises, cladograms and real-world examples connect theory to observation. The book highlights how evolutionary thinking underpins conservation, agriculture and medicine. It is written for undergraduate students and readers exploring the breadth of biological sciences.