Wolves, like the one shown on the front cover guarding a skeleton of a caribou, were close to extinction in the 1930s. In Yellowstone National Park, the removal of the wolves had ripple effects on the ecosystem. Without a natural predator, the elk population increased, and the preferred food source of the elks— cottonwood and willow trees—began to dwindle. With fewer trees to stabilize the …
The human body is an amazing biological machine, capable of extreme activities, such as high-elevation rock climbing. While the climber is focusing on her next handhold, the body is coordinating the actions of multiple body systems to ensure that the machine functions at peak performance. For each movement, the nervous system must process thousands of signals from the outside environment. In…
The mission of Mader's text, Biology, has always been to give students an understanding of biological concepts and a working the scientific process. The concepts of biology and the methodology of science can be used to understand the particulars of new ideas or of a system, on any scale, from the cell to the biosphere. In the twenty-first century, students are being exposed, almost on a dai…