Evolution
By Laura Klappenbach, About.com Guide
Basic Evolution Concepts
To gain a solid understanding of evolution, it's important to become familiar with some basic terms and concepts. Here you'll find information about what evolution is, the different scales at which evolution acts, and how species change over time. You'll also explore the history of evolutionary thought and the technological advances that have enhanced our study of evolution.
- What is Evolution?
- What is Microevolution?
- What is Macroevolution?
- What is Descent with Modification?
- The Evolutionary Process
Charles Darwin
Charles Darwin (1809–1882) was arguably the most influential scientist of the modern era. His theory of natural selection, shaped in part by his round-the-world voyage as ship's naturalist aboard the HMS Beagle, forever changed the way we understand life on earth. Darwin was both a gifted and prolific writer—through his writings we gain insight into the natural world and the mind of a great naturalist.
Evolution of Animal Groups
Every group of organisms has a unique evolutionary history that provides a wealth of information about the individual species belonging to that group. Here we'll examine some of the major groups of animals—birds, fish, insects, mammals, and reptiles—and explore what scientists know of their evolutionary history, phylogenetic relationships, and fossil records.
- The Basics of Vertebrate Evolution
- The Evolution of Key Animal Traits
- The Evolutionary Tree of Mammals
Extinction / Speciation
Speciation and extinction are the processes by which new species arise and existing species decline and cease to exist. Speciation and extinction events are an integral part of evolution and are taking place all the time. At some points during evolutionary history, extinction or speciation rates become elevated, resulting in mass extinctions or bursts of rapid speciation.
Fossil Discoveries / Fossil Record
The history of life on Earth is recorded in sediments and rocks as fossil remains. When fossils are considered in the context of geological history, scientists can begin to describe the changes in organisms that have taken place over vast expanses of time. Here we'll explore how fossils form, how they are prepared, and what they can tell us about life on earth, past and present.
Natural Selection
Natural selection is an evolutionary mechanism by which traits unsuited for a particlar condition are diminished while traits better suited for those conditions become established in a population. Natural selection is founded on a handful of simple concepts—the variation of traits within a population, differential reproduction, and heritability of traits.
Phylogenetics
Phylogenetics is a powerful tool used by scientist to describe lineages of organisms past and present in the context of evolution. The basic tool of phylogenetics is the cladogram, a tree-like drawing that depicts groups organisms, also known as clades, in a way that elucidates their relationships. Cladograms enable scientists to propose and test hypotheses about evolutionary relationships.
Timeline of Biological History
Explore the 4.5-billion-year history of our planet from its lifeless molten beginnings to the present day and look at how scientists break down our planet's history into eons, eras, and periods. By grasping how organisms, past and present, have evolved and diversified throughout the history of our planet, we can better appreciate the animals and wildlife that surround us today.