In Brief
TRENDS in Ecology & Evolution Vol.17 No.6  June 2002
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254 News&Comment
The genetic material that makes up each
chromosome of a higher organism is not
haphazardly distributed throughout the cell
nucleus, but is neatly packed into spatially
distinct chromosome territories. Whether
chromosome territories are arranged in
particular patterns within the nucleus, and if
so, whether such patterns are functionally
relevant, has been controversial. A new
evolutionary study of the nuclear
arrangement of chromosome territories
now provides strong support for non-
random chromosome organization and its
functional importance in mammals [1].
A striking example of a non-random
arrangement of chromosomes is that of human
chromosomes 18 and 19. Chromosome 18 is
one of the gene-poorest human chromosomes,
but chromosome 19 is one of the gene richest.
Strikingly, chromosome 18 is preferentially
found at the periphery of the nucleus, whereas
chromosome 19 is preferentially found towards
the nuclear center. The correlation between
gene density and preferential internal
positioning not only holds for these two
chromosomes but for the entire set of human
chromosomes. From this observation,
one might predict that, if positioning of
chromosomes is of functional importance for
an organism, chromosome arrangements
might be maintained during evolution.
Cremer and colleagues [1] tested this
prediction by comparing the nuclear
position of chromosomes 18 and 19 in
higher primates ranging from humans to
the squirrel monkey, which is evolutionarily
separated from humans by ~30 million
years. In all species, the genetic material
from chromosome 18 was at the periphery
and chromosome 19 material was more
centrally located. These results are all the
more remarkable because chromosomes
undergo rearrangements during evolution.
For example, the genetic material
corresponding to human chromosome 19 
is found on three separate chromosomes 
in gibbons. Nevertheless, these regions
behaved like human chromosome 19
material and they clustered in a central
position in the interior of the nucleus.
Evolutionary conservation of
chromosome arrangements strongly
supports a functional role for chromosome
positioning. One possibility is the silencing of
genes by association with heterochromatin,
which is often more prevalent in the nuclear
periphery. Another possibility is that groups
of genes cluster within the nucleus to form
nuclear neighborhoods, which are optimized
for their gene expression and regulatory
needs. Whatever the function of non-random
chromosome arrangements, clearly the 
most intriguing open question is how these
patterns are established and maintained and
what happens when they are disrupted.
1 Tanabe, H. et al. (2002) Evolutionary conservation
of chromosome territory arrangements in cell
nuclei from higher primates. Proc. Natl. Acad. Sci.
U. S. A. 99, 4424?3329
Tom Misteli
mistelit@mail.nih.gov
Chromosomes in space and time
The canopies of tropical lowland rainforests
host some of the most diverse arthropod
communities on Earth. But whereas the
crowns of boreal trees usually teem with free-
feeding and slow-moving lepidopteran
caterpillars, such creatures are all but lacking
from many canopies in the lowland tropics.
In their absence, the quick-moving nymphs
of Hemiptera (bugs) or Orthoptera (katydids,
crickets and grasshoppers) dominate the
youth scene. Why this difference? Some
studies have emphasized the fact that fogging
samples from lowland rainforest canopies
often abound with ants. If these animals all had
a taste for insect flesh, they would certainly
exert a high predation pressure on any
caterpillars slow enough for them to catch.
In a recent study, Andreas Floren et al. [1]
make the move from hypothetical connection
to empirical observation by measuring ant
predation in a Malaysian lowland rainforest.
Floren?s group presented moth caterpillars 
to 54 ant species roaming around in the tree
crowns. As expected, most of the ants (85%)
readily devoured any caterpillar that was
offered to them. Floren et al. then fogged ten
tree canopies. Among the vast number of ants
collected, >80% belonged to the 46 species
that had eaten caterpillars in the tests.
These results clearly demonstrate how
strong the predation pressure could be that
ants exert on their fellow arthropods. And, by
eating any slow and unprotected animal that
they come across, ants might mould the whole
structure of tropical canopy communities.
From a conservation perspective, this implies
that any disturbance to the ants will have
profound repercussions throughout the
arboreal insect community. Such effects have
already been revealed by the work of Floren
et al. ? by comparing primary forest with
disturbed sites, they showed that the
proportion of predacious ants decreased with
human disturbance, resulting in a higher
abundance of caterpillars. Thus, Floren et al.
assign a key role to the ants in the Malaysian
rainforest drama ? the voracious but sensitive
architects of the canopy ecosystem. Whether
they will take on the same part in other tropical
areas is something that remains to be seen.
1 Floren, A. et al. (2002) Arboreal ants as key
predators in tropical lowland rainforest trees.
Oecologia 131, 137?144
Tomas Roslin
tomas.roslin@helsinki.fi
Arboreal antics
Eco-crimes to be punished in
Mexico
The punishment
metered out to
criminals tells us a lot
about a society?s
values and priorities.
Although most
nations have laws that attempt to prevent
environmentally destructive activities, rarely
do we see ?environmental crimes? go to trial.
In the first such prosecution in Mexico, a man
charged with breaking an environmental law
faces the possibility of facing three to eight
years in jail if found guilty. This precedent-
setting case involves the charge of tampering
with an automobile emissions measuring
device so that it falsely recorded ?passing
scores? even though emissions did not
satisfy government regulations.
The alleged crime was detected at one of
Mexico City?s 162 auto-inspection centers, which
are responsible for enforcing regulations aimed
at reducing the city?s well-known air pollution
problems. It is believed that eliminating
corruption at emissions-testing centers could
markedly improve air quality in the capital
TRENDS in Ecology & Evolution Vol.17 No.6  June 2002
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255News&Comment
city. Environmentalists are applauding this
case, and are calling for more such
prosecution of environmental criminals.  PK
US EPA seeks major new
funding to address water
pollution
The EPA has requested US$21 million to target
20 polluted watersheds throughout the USA.
The initiative is intended to elicit community-
based action that focuses on watersheds
that are noteworthy for their economic or
biological value. This new program is one of
many recommendations from a recent report
on the status of watersheds throughout
North America (http://www.epa.gov/
owow/forum/report.html). In spite of
worldwide efforts at improving water quality,
many watersheds suffer from sedimentation,
metals, pathogens, excessive nutrients,
habitat loss and invasive species. Top-down
government regulations have certainly
improved water quality, but sources of
watershed degradation are so numerous,
insidious and widespread, that here is little
hope of achieving desired improvements
without strong local community support.
This new program is only a start, but it is
hoped that the pilot will be so successful
that it will spread to watersheds throughout
the USA. The fact that a federal regulatory
agency is turning to community-based
action is evidence of a general strategic shift
in government institutions throughout the
world; this shift reflects an appreciation for
the limitations of top-down environmental
regulation.  PK
The battle to halt illegal logging
Several governments and international
organizations are increasing the amount of
attention paid to the environmental threats
posed by illegal logging. In numerous tropical
and temperate nations, illegal loggers 
are stealing valuable timber, flaunting
environmental laws, invading national parks,
and engaging in bribery and corruption.
The alarming scope of illegal logging is
highlighted in a recent newsletter published
by the International Tropical Timber
Organization (http://www.itto.or.jp), which
shows that illegal logging accounts for a
large proportion of all the wood products
sold worldwide. In countries such as Ghana
and Russia, 20?50% of all timber is harvested
illegally, with estimates reaching 80?90% for
nations such as Cambodia and Brazil. Even
in British Columbia, Canada, timber worth
US$200?320 million is stolen annually.
Fortunately, efforts to halt forest crimes
are increasing. Last year, illegal logging was
condemned in key ministerial conferences
in Bali and Rome. The Indonesian Navy
seized a large shipment of stolen timber
from Borneo, and Brazil is cracking down on
the illegal mahogany trade. But all parties
agree that illegal logging remains an
enormous challenge that can only be
reduced by increased vigilance,
international cooperation and pressure
from nongovernmental organizations. WFL
China Government seeks
advice on how to pursue
conservation planning
In April 2002, the
Chinese Environmental
Protection Agency
(SEPA) sent
representatives from
every province in China
to participate in a
workshop on methods
for broadscale
conservation planning.
The workshop, which SEPA co-sponsored
with The Nature Conservancy, reflects a
countrywide mandate to pursue
conservation planning to allow for the
protection of biodiversity. Development of
infrastructure (e.g. dams, factories and
roads), expanding cities, conversion of land
to agricultural uses, and population growth
are all threats to biodiversity in China.
Because China contains an estimated
10% of the world?s biodiversity, protecting
biodiversity in this country should be a
concern for all conservation biologists. The
fact that conservation planning is a state-
sanctioned priority offers some hope; many
wealthy western nations do not have a
strong national commitment to conservation
planning. One reason why China might be
receptive to conservation efforts are the
demonstrations of damaged ecosystems
leading to huge economic losses, such as the
recent dust storms in Beijing, or the Yangtze
River floods of 1998.  PK
Environmental litigation at the
center of controversy in Chile
A US$1.4 billion dollar timber project 
planned for central Chile has been halted by 
a federal court for failing to file an adequate
environmental impact statement. The halted
project, which includes a huge sawmill and
pulp mill, is opposed by several local citizen
groups, which are worried about impacts on
wineries, fisheries and farms. The mills would
use chlorine and produce dioxins, which
could severely damage the region aquatic
resources according to the plaintiffs. The case
is, however, not settled, because it is being
appealed before Chile?s Supreme Court.
What makes this story so interesting is
that, previously, litigation has not played a
prominent role in Chilean conservation.
Many are applauding the possibility that
environmental litigation could become a
forceful tool for insuring that conservation
and environmental values are respected
more broadly in Latin America.  PK
Disingenuous attack on the
US Endangered Species Act
The US Congress is yet again considering
several modifications of the Endangered
Species Act (ESA) that conservation and
ecological leaders feel would dangerously
weaken the act. Attacks on the ESA are
almost an annual ritual in congress, even
though public opinion polls repeatedly 
find strong support for the protection of
threatened species. But this year?s attempts
to revamp the ESA are something of a
?sheep in wolves clothing?.
The most notable is the ?Sound Science
for Endangered Species Act Planning Act?
proposed by an Oregon Republican
congressman (http://www.walden.house.gov/
issues/esa/index.html). This proposed new
law claims to want to strengthen the role of
science in endangered species management
by requiring peer reviews by panels of
external scientists, and by establishing so-
called standards for data. Environmentalists
and several prominent ecologists have
noted that there already are peer reviews
and that, in fact, this proposed law seeks to
retard implementation of the act, motivated
in part by a congressman?s advocacy for
farm irrigation at the expense of preserving
water for endangered Northwest salmon
(http://www.stopextinction.org/action/
KlamathCP.html). Perhaps we should take
heart that ?sound science? is seen as a
banner under which to float any cause.  PK
William F. Laurance
laurancew@tivoli.si.edu
Peter Kareiva
peter_kareiva@yahoo.com