Balancing biodiversity
Pan European Networks: Science & Technology
Halldór Stefánsson,
EMBL’s programme
manager for the
Science and Society
he main aim of the ‘Biodiversity in the Balance: Causes and
Consequences’ EMBL/EMBO Science & Society public conference,
which took place in November 2012, was to engage a group of
experts to present to a mixed audience, in a manner accessible to all, insights
into the origins and nature of biodiversity, as well as its implications for
sustaining a wholesome life on the planet. While we never thought that it
would bring about (where others had failed) spectacular solutions to perceived
planetary problems, what we set out to do with this communication event
was simply to raise consciousness and to facilitate a broad dialogue between
scientists and members of the public.
The conference opened with a fascinating keynote lecture by the renowned
microbiologist Rita Colwell (University of Maryland and Johns Hopkins
University Bloomberg School of Public Health, USA). She spoke about the
complexity of cholera transmission and the evolution of the genome of the
Vibrio Cholerae,
and explained how pathogenic micro-organisms
do not exist in a vacuum, but rather require appropriate environmental
conditions, presence of intermediate hosts or vectors, and, for human
pathogens, appropriate social and economic factors that allow for infection.
She also explained that the various strains of the bacterium that appear,
and reappear, are a direct manifestation of its high evolutionary adaptability
to changing environments.
For the purposes of this meeting we took ‘biodiversity’ to refer to the
variation of life at all levels of biological organisation – genes, species,
and ecosystems – in all their evolved manifestations on the planet. At
the outset of the conference we focused on questions such as: why is
the living world so diverse? What forces and processes led to the
evolution and proliferation of so many species? How do species come
into being, how do they become distinct from one another?
Biodiversity as we know it is the result of billions of years of evolution,
shaped by natural processes and, increasingly, by humans. What evidence
is there that suggests that biodiversity is becoming substantially reduced
on a planetary scale? These were some of the basic questions that were
tackled by our first three speakers in the opening session of the conference.
The paleontologist Michael Benton (University of Bristol, UK) spoke about
the origins of life on land, providing an overview of the major episodes
that have shaped the 3.2 billion years of life on Earth, and the Cretaceous
Terrestrial Revolution in particular, an event that fundamentally
determined modern terrestrial ecosystems.
Axel Meyer (University of Konstanz, Germany) spoke about patterns and
processes of speciation, focusing on his own ecological evodevo work on
cichlid fishes in Africa and South America. He put some of the underlying
theoretical concepts into historical context,
recalling the divergence in views between
Charles Darwin and Ernst Mayr.
lkka Hanski (University of Helsinki, Finland), the
last speaker in the session, presented evidence
showing that biodiversity on the planet is being
increasingly threatened with the actual rate of
species loss growing alarmingly. Hence, we
are apparently in the midst of the sixth mass
extinction, which may have started 50,000
years ago with expanding human populations.
Hanski argued that the main cause of declining
biodiversity is due to habitat loss and
fragmentation. He discussed two key concepts
related to the impact of habitat loss and
fragmentation on the viability of species:
‘extinction threshold’ and ‘extinction debt’. The
former relates to the limits to species viability as
their habitats become fragmented and are
encroached upon by external forces, while the
latter refers to ‘the living dead’ – species that have
been driven beyond the ‘extinction threshold’.
To halt the loss of biodiversity in human-
dominated landscapes Hanski argues that we
need to set aside clusters of protected areas, for
instance by designating one third of the total
land area on earth as ‘conservation landscapes’,
The Tree of Life
(P Bork, EMBL)
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