Mating System of the California Sea Lion (Zalophus californianus)
Biology 342, Fall 2014
Every year, up and down the Pacific coast of North America and in the Gulf of California, California sea lions (Zalophus californianus) congregate in huge numbers to form breeding colonies. In these colonies, a few large males defend territories occupied by many females (see photo below). The rest of the males have no territories, which are also known as harems. The females give birth to a single pup, and then shortly afterward breed with the male of their territory. It is a classic polygynous mating system, in which a small number of dominant males father the overwhelming majority of pups, while most males father none.
However, our knowledge of the mating system has been upset in recent years by the ability to use molecular genetic techniques to assign paternity to pups. California sea lions may not be truly as polygynous as we had thought, because what we see on the beaches does not correspond to actual paternity patterns. The real mating system is more complex. There is much researchers still do not know.
What Does This Website Do?
This website presents both the traditional and newer knowledge of the mating system of California sea lions, referencing primary literature where possible.
For traditional knowledge, see What We Thought. This knowledge is not incorret per se, but is an overly simplistic model of the system.
For recent research, see What We Think Now. This less of an new understanding of the system, and more a new understanding of the errors in the traditonal model.
For theories of the evolution of the system, see How It Evolved. This includes both the traditional theory and a newer one.
For a list of works cited in this website, as well as links to relevant Wikipedia pages and research labs, see References & Research. These Wikipedia links are also interspersed throughout the text.