Campbell, Chapter 55

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CONSERVATION BIOLOGY
Campbell, Chapter 55
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Conservation Biology
pages 1224-1225
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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.
FIG. 55.1
pages 1225-1226
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WHY PRESERVE BIODIVERSITY?
pages 1226-1228
Overall benefitcost ratio of an effective global
program for conservation of remaining wild nature
is at least 1001.
Change in area or abundance of vertebrates
declined in last 10 yrs. in valuable biomes.
Science 2002
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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 Earths 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
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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.
Biologically optimal
Including socioeconomics
Science 2002
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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
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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.
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.
Science 2005
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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.
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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
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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.
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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
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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
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Lack of predators
White-tailed deer and ginseng.
Science 2005
U.S. Fish. Wildl. Serv.
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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
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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