CONSERVATION BIOLOGY Campbell Chapter 55 Conservation Biology pages

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 1960 s and directly harvested since the 1980 s. 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