Radiations, or Evolution in Action We have just celebrated the "Darwin
Year" with the double anniversary of his 200th birthday and 150th year
of his masterpiece, "On the Origin of Species by means of Natural
Selection". In this work, Darwin established the factual evidence of
biological evolution, that species change over time, and that new
organisms arise by the splitting of ancestral forms into two or more
descendant species. However, above all, Darwin provided the mechanisms
by arguing convincingly that it is by natural selection - as well as by
sexual selection (as he later added) - that organisms adapt to their
environment. The many discoveries since then have essentially con?rmed
and strengthened Darwin's central theses, with latest evidence, for
example, from molecular genetics, revealing the evolutionary
relationships of all life forms through one shared history of descent
from a common ancestor. We have also come a long way to progressively
understand more on how new species actually originate, i. e. on
speciation which remained Darwin's "mystery of m- teries", as noted in
one of his earliest transmutation notebooks. Since speciation is the
underlying mechanism for radiations, it is the ultimate causation for
the biological diversity of life that surrounds us.