Campbell, Chapter 55

CONSERVATIONBIOLOGY

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.

FIG. 55.1pages 1225-1226

WHY PRESERVE BIODIVERSITY?

Science 2002

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.

pages 1226-1228

Nature 2000

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.

WHERE TO PRESERVE BIODIVERSITY?

Science 2002

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

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

Biodiversity loss and poverty are linked problems.

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).

WHAT ARE THE MAJOR THREATS TO BIODIVERSITY?

Richness determined by patch area and habitat diversity NOT degree of isolation.

Birds in habitat fragments

Biol. Conserv. 2003

Naturally-fragmented area, 5,000+ years after fragmentation. Resident birds of humid pine-oak forest.

pages 1228-1229

FIG. 55.6

Farming is the greatest extinction threat to birds (the best known taxon), and its adverse impacts look set to increase, especially in developing countries.

Science 2005

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.

The intensification and expansion of modern agriculture is amongst the greatest current threats to worldwide biodiversity.

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 SpeciesSerious 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

Native of South America, first appeared in Louisiana in 1891 and in California in 1907.

T. Glynn

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

Proc. Natl. Acad. Sci. 2003

Native ant communities in California.No Argentine ant: show species segregation due to competition.

Yes Argentine ant: show species aggregation or randomness.

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.

Science 2003

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 2004

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 2005U.S. Fish. Wildl. Serv.

Lack of predators

White-tailed deer and ginseng.

Humans might be causing climate change by increasing carbon dioxide concentration in the atmosphere.

Science 2005

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).

OTHER HUMAN IMPACTS

Projected changes in reef calcification rate

Science 1999

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.