Biology 2e is designed to cover the scope and sequence requirements of a typical two-semester biology course for science majors. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology includes rich features that engage students in scientific inquiry, highlight careers in the biological sciences, and offer everyday applications. The book also includes various types of practice and homework questions that help students understand—and apply—key concepts. The 2nd edition has been revised to incorporate clearer, more current, and more dynamic explanations, while maintaining the same organization as the first edition. Art and illustrations have been substantially improved, and the textbook features additional assessments and related resources.

By the end of this section, you will be able to do the following:

Define biodiversity in terms of species diversity and abundance
Describe biodiversity as the equilibrium of naturally fluctuating rates of extinction and speciation
Identify historical causes of high extinction rates in Earth’s history

Paul Andersen explains how biodiversity can be measured through genetic, species, or ecosystem variety on the planet. Species diversity is increased through speciation and decrease through extinction. The mechanism for speciation is evolution through natural selection. The planet provides ecosystem services at no cost to humanity. [7:08]

University of California site showcases how different types of organisms exist on the Earth and the history of life.

Find information about diversity among genes, species, and ecosystems that helps answer questions about the importance of biodiversity and how we can save species from extinction.