Geoscience Reference
In-Depth Information
Chapter 2
Nature
Bruce Braun
Introduction
In 2001, researchers from University College London documented a massive imbal-
ance in the sex ratio of Blue Moon butterfl ies on the Samoan Islands of Savali and
Upolu. Males, they discovered, accounted for only 1 percent of the population.
Biologists now believe that the imbalance was caused by the parasitic Wolbachia
bacteria, which is passed down from mothers and kills male embryos before they
hatch. When they surveyed the islands fi ve years later, however, they were surprised
to fi nd that males accounted for about 40 percent of the population. What explains
the dramatic recovery? Scientists postulate that the comeback was due to 'suppres-
sor' genes that controlled the bacteria and that this was, in the words of one member
of the research team, 'the fastest evolutionary change that has ever been observed'
(quoted by
BBC News
, 2007). The same researcher went on to suggest that the
example further strengthened the view that parasites may be one of the major drivers
in evolution.
Shift to a somewhat different context in Birmingham, England. Here conserva-
tionists have noted some peculiar changes in the behaviour of water voles. In this
urbanised setting, the voles have apparently learned to live with the brown rat,
usually considered to be a predator (Hinchliffe, 2008). Urban ecologies, it appears,
can give rise to new capacities in animals, scrambling a system of classifi cation
that presupposes that all members of a species of vole are the same, and thus,
interchangeable. Yet, urban and rural voles, it seems, do not exhibit the same
behaviours.
Finally, consider our endless battle with infectious diseases. In the years after the
Second World War, public health offi cials, at least in the 'developed' world, imag-
ined that through quarantine and immunisation as well as the wide use of antibiotics
and vaccines, such diseases would be eliminated, and we would experience an 'epi-
demiological transition' where infectious diseases would increasingly be dispatched
to the dustbin of history. Today, we seem threatened with new and emerging infec-
tious diseases like never before. More than this, though, new work in microbiology
