Chapter 9 Sustaining Biodiversity The Species Approach Pgs

Chapter 9 Sustaining Biodiversity: The Species Approach Pgs. 183 -194

Chapter Overview Questions Ø How do biologists estimate extinction rates, and how do human activities affect these rates? Ø Why should we care about protecting wild species? Ø Which human activities endanger wildlife? Ø How can we help prevent premature extinction of species? Ø What is reconciliation ecology, and how can it help prevent premature extinction of species?

Core Case Study: The Passenger Pigeon - Gone Forever Ø Once the most numerous bird on earth. Ø In 1858, Passenger Pigeon hunting became a big business. Ø By 1900 they became extinct from overharvest and habitat loss. Figure 11 -1

SPECIES EXTINCTION Ø Species can become extinct: l l l Locally: A species is no longer found in an area it once inhabited but is still found elsewhere in the world. Ecologically: Occurs when so few members of a species are left they no longer play its ecological role. Globally (biologically): Species is no longer found on the earth.

Global Extinction Ø Some animals have become prematurely extinct because of human activities. Figure 11 -2

Passenger pigeon Great auk Dodo Dusky seaside sparrow Aepyornis (Madagascar) Fig. 11 -2, p. 223

Endangered and Threatened Species: Ecological Smoke Alarms Ø Endangered species: so few individual survivors that it could soon become extinct. Ø Threatened species: still abundant in its natural range but is likely to become endangered in the near future. Figure 11 -3

Fig. 11 -3, p. 224

Grizzly bear Utah prairie dog Kirkland’s warbler Knowlton cactus Florida manatee Swallowtail butterfly Humpback chub Golden lion tamarin African elephant Siberian tiger Fig. 11 -3, p. 224

Giant panda Black-footed Whooping crane ferret Mountain gorilla Florida panther California condor Northern spotted owl Hawksbill sea turtle Blue whale Black rhinoceros Fig. 11 -3, p. 224

SPECIES EXTINCTION Ø Some species have characteristics that make them vulnerable to ecological and biological extinction. Figure 11 -4

Characteristic Low reproductive rate (K-strategist) Specialized niche Narrow distribution Examples Blue whale, giant panda, rhinoceros Blue whale, giant panda, Everglades kite Many island species, elephant seal, desert pupfish Feeds at high trophic Bengal tiger, bald eagle, grizzly bear level Fixed migratory patterns Blue whale, whooping crane, sea turtles Rare Many island species, African violet, some orchids Commercially valuable Snow leopard, tiger, elephant, rhinoceros, rare plants and birds Large territories California condor, grizzly bear, Florida panther Fig. 11 -4, p. 225

SPECIES EXTINCTION Ø Scientists use measurements and models to estimate extinction rates. l l The International Union for the Conservation of Nature and Natural Resources (IUCN) publishes an annual Red List, listing the world’s threatened species. The 2004 Red List contains 15, 589 species at risk for extinction. Figure 11 -5

SPECIES EXTINCTION Ø Percentage of various species types threatened with premature extinction from human activities. Figure 11 -5

34% (51% of freshwater species) Fish 25% Mammals 20% Reptiles Plants Birds 14% 12% Fig. 11 -5, p. 225

SPECIES EXTINCTION Ø Scientists use models to estimate the risk of particular species becoming extinct or endangered. Figure 11 -6

Number of species existing 5 million 14 million 50 million 100 million Effects of a 0. 1% extinction rate 5, 000 extinct per year 14, 000 extinct per year 50, 000 extinct per year 100, 000 extinct per year Number of years until one million species are extinct Fig. 11 -6, p. 226

IMPORTANCE OF WILD SPECIES Ø We should not cause the premature extinction of species because of the economic and ecological services they provide. Ø Some believe that each wild species has an inherent right to exist. l Some people distinguish between the survival rights among various types of species (plants vs. animals).

HABITAT LOSS, DEGRADATION, AND FRAGMENTATION Ø Conservation biologists summarize the most important causes of premature extinction as “HIPPO”: l l l Habitat destruction, degradation, and fragmentation Invasive species Population growth Pollution Overharvest

HABITAT LOSS, DEGRADATION, AND FRAGMENTATION Ø The greatest threat to a species is the loss, degradation, and fragmentation of where it lives. Figure 11 -7

Habitat Pollution Overfishing loss Habitat degradation Commercial hunting Climate change and fragmentation and poaching Introducingnonnativ Sale of exotic Predator and pest control e species petsand decorative plants Secondary Causes • Population growth • Rising resource use • No environmental accounting • Poverty Basic Causes Fig. 11 -7, p. 229