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CONSERVATION
BIOLOGY
Campbell, Chapter 55
Conservation Biology
pages 1224-1225
LEVELS OF BIOLOGICAL DIVERSITY (BIODIVERSITY)
Genetic Diversity. Includes genetic
variation within and between
populations, associated with adaptations
to local conditions.
Species Diversity. Variety of species
in an ecosystem or throughout the
biosphere (species richness).
Ecosystem Diversity. Variety of
ecosystems throughout the biosphere.
pages 1225-1226
FIG. 55.1
WHY PRESERVE BIODIVERSITY?
pages 1226-1228
Overall benefit:cost ratio of an effective
global program for conservation of
remaining wild nature is at least 100:1.
Change in
area or
abundance
of
vertebrates
declined in
last 10 yrs.
in valuable
biomes.
Science 2002
WHERE TO PRESERVE BIODIVERSITY?
Biodiversity Hotspots. High concentrations of endemic species enduring huge
loss of habitat. 44% of known vascular plants and 35% of known vertebrates
(except fish) confined in 25 spots covering 1.4% of Earth’s land surface.
Nature 2000
Coral Reefs. Many
reef fish, corals,
snails, and lobsters
have restricted ranges
and are clustered into
centers of endemism.
Ten richest centers
cover 15.8% of coral
reefs (0.012% of the
oceans) and include
44.8-54.2% of restricted-range species.
Science 2002
Biodiversity loss and poverty are linked problems.
Marine reserve networks in the Gulf of California, Mexico.
Use multiple levels of information on biodiversity, ecological processes, and
socioeconomic factors. A network covering 40% of rocky reef habitat can fulfill
many conservation goals while reducing social conflict.
Science 2002
Biologically optimal
Including socioeconomics
WHAT ARE THE MAJOR THREATS TO BIODIVERSITY?
1- Habitat Destruction/Fragmentation
Most studies conducted in human-fragmented
areas less than 100 years after fragmentation.
Key determinants of richness are patch area,
habitat diversity and degree of isolation (distance
from nearest large fragment). pages 1228-1229
Birds in habitat fragments
FIG. 55.6
Naturally-fragmented
area, 5,000+ years after
fragmentation. Resident
birds of humid pine-oak
forest.
Richness determined by patch area and
habitat diversity NOT degree of isolation.
Biol. Conserv. 2003
The intensification and expansion of modern agriculture is amongst the
greatest current threats to worldwide biodiversity.
Farming is the greatest extinction threat to
birds (the best known taxon), and its adverse
impacts look set to increase, especially in
developing countries.
Two competing solutions: wildlife-friendly
farming and land sparing. Evidence from a
range of taxa in developing countries suggests
that land sparing may allow more species to
persist.
Science 2005
Organic farming needs more land to produce
same yield as conventional farming, but
reduces fertilizer, energy and pesticide input,
and maintains fertility and biodiversity of
cropped lands.
2- Introduced Species
Serious threat to community structure and ecosystem function. Reduce
species numbers and alter native communities.
Argentine ant (Linepithema humile).
Most invasive ant
species in the world.
P. S. Ward
T. Glynn
Native of South America, first
appeared in Louisiana in 1891
and in California in 1907.
Introduced into Europe ~80 years
ago, developed the largest
supercolony recorded: stretches
6,000 km with billions of related ants.
Proc. Natl. Acad. Sci. 2002
Native ant communities in California.
No Argentine ant: show species
segregation due to competition.
Yes Argentine ant: show species
aggregation or randomness.
Proc. Natl. Acad. Sci. 2003
3- Overexploitation
Pelagic longlines and shark populations
Sharks caught as by-catch in pelagic longline fisheries since the 1960s and
directly harvested since the 1980s.
Pelagic longlines are the most widespread fishing gear used in the open
ocean.
Rapid large declines in large coastal and oceanic shark populations in NW
Atlantic. Scalloped hammerhead, white, and thresher sharks each have
declined by over 75% in the past 15 years.
Science 2003
Fishing supply (marine) and bushmeat hunting (terrestrial)
The study shows need to develop cheap
protein alternatives to bushmeat and to
improve fisheries management by foreign
and domestic fleets to avert extinction of
tropical wildlife.
Science 2004
Lack of predators
White-tailed deer and
ginseng.
U.S. Fish. Wildl. Serv.
Science 2005
OTHER HUMAN IMPACTS
Humans might be causing climate change by increasing carbon dioxide
concentration in the atmosphere.
Temperature records recovered from tree rings and other proxies broadly
agree that the past couple of decades are still the warmest of the past
1000 years (black).
Science 2005
One consequence of climate change is a
decline in the calcification rate of corals.
The expected primary effects of
reduced calcification are weaker
skeletons, reduced extension
rates, and increased susceptibility
to erosion. These primary effects
will lead to a host of secondary
changes in community structure,
reproduction, and overall
community function.
Projected changes in reef calcification rate
Science 1999