Travel Reference
In-Depth Information
In the previous chapter we visited some of the further branches of the great
evolutionary tree of life. We asked whether it might be possible to recreate, or
at least imitate, some of the early evolutionary changes that took place down
near the base of these branches, changes that eventually led to the diversity
of present-day animals.
It is clear that the Darwinian process of natural selection must have
been the primary force that drove those early events, but natural selection
is only a part—albeit a most important part—of how evolution happens. In
this chapter we will examine some further examples of evolution in action,
in places ranging from the heat-blasted soils of Israel's Negev Desert to the
dense mangrove forests of southern Borneo. In the process we will explore
in detail how evolution actually takes place.
Evolution Canyon—a Darwinian laboratory
Recently a group of us, fresh from a meeting at Haifa University to com-
memorate the bicentenary of Darwin's birth, accompanied the evolutionary
biologist Eviatar Nevo on a fi eld trip. He took us to his favorite research site in
northern Israel and gave us a demonstration of how evolution is taking place
before our very eyes.
Nevo, a lively snowy-haired octagenarian with an overwhelming pas-
sion for science, is the founder of Haifa University's Institute of Evolution.
He strode confi dently into the canyon that he has studied for forty years. The
canyon, oi cially called Nahal Oren, is one of several that run east and west
along the slopes of Mount Carmel, less than an hour's drive from the spec-
tacular coastal city of Haifa. Here the air is fresh, birds sing, and oleanders
and Judas trees bloom on the valley's sunny fl oor.
The northern and southern slopes of the valley dif er dramatically. On
the wetter and more shaded north-facing slope the vegetation is plentiful,
with scrub oaks, wild olives, and other small trees predominating. Just a few
hundred meters away across the valley fl oor is the sun-drenched south-fac-
ing slope, a rocky terrain covered with dry grasses and dotted with acacia
shrubs. The north-facing slope resembles southern Europe's Mediterranean
 
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