PBS
Pbs: A Modern Mass Extinction
Are we in the midst of a mass extinction? Is Homo sapiens triggering this mass extinction? Four expert panelists have written responses to the aforementioned questions for this highly informative site.
Other
Evidence for Evolution: Formation of New Species
These pages are part of a site called Evolution that accompanies a textbook by the same name. Mark Ridley is the author. These pages offer an explanation of speciation using reproductive isolation and differences in phenotype.