but species are distinct from each other, suggesting that some process has created a discontinuity, or gap, between them. Credit for doing the most to crack this puzzle goes to Ernst Mayr ...

species-related questions became even more difficult. In the mid-1900s the leading evolutionary biologists, Ernst Mayr and George G. Simpson, contributed two key ideas about the basic nature of ...

In 1942, biologist Ernst Mayr coined what is perhaps the most enduring one: the biological species concept, which labels two organisms as different species if they cannot reproduce and create ...

which some call the "species problem" or the "species crisis." Another definition -- one not necessarily at odds with Mayr's -- is that a species is a classification containing organisms that are ...

But in the mid-20th century, biologist Ernst Mayr proposed a more rigorous definition, known as the biological species ...