On the cover, a mother polar bear (Ursus maritimus) and her cub explore an open channel in the ice in North Baffin National Park, Canada. The polar bear...
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Résumé
On the cover, a mother polar bear (Ursus maritimus) and her cub explore an open channel in the ice in North Baffin National Park, Canada. The polar bear is listed as a vulnerable species by the IUCN/World Conservation Union. Both biological and social factors threaten the survival of polar bears. These factors include low reproductive rates and exposure to toxic pollutants. Pollutants become increasingly concentrated as they gradually pass up the food chain to reach these predators. In addition, humans often perceive polar bears as competitors or threats. Finally, the circumpolar geographic range of this species crosses national boundaries and includes international waters, making enforcement of protective legislation extremely difficult.
Sommaire
VERTEBRATE DIVERSITY FUNCTION, AND EVOLUTION
The Diversity, Classification, and Evolution of Vertebrates
Vertebrate Relationships and Basic Structure
Early Vertebrates: Jawless Vertebrates and the Origin of Jawed Vertebrates
AQUATIC VERTEBRATES: CARTILAGINOUS AND BONY FISHES
Living in Water
Radiation of the Chondrichthyes
Dominating Life in Water: The Major Radiation of Fishes
Geography and Ecology of the Paleozoic
TERRESTRIAL ECTOTHERMS: AMPHIBIANS, TURTLES, LEPIDOSAURS, AND ARCHOSAURS
Origin and Radiation of Tetrapods and Modifications for Life on Land
Salamanders, Anurans, and Caecilians
Turtles
The Lepidosaurs: Tuatara, Lizards, and Snakes
Ectothermy: A Low-Cost Approach to Life
Geography and Ecology of the Mesozoic
Mesozoic Diapsids: Dinosaurs, Crocodilians, and Others
ENDOTHERMS: BIRDS AND MAMMALS
The Evolution of Birds and the Origin of Flight
The Ecology and Behavior of Birds
The Synapsida and the Evolution of Mammals
Geography and Ecology of the Cenozoic
Mammalian Characteristics and Diversity
Mammalian Adaptations
Endothermy: A High-Energy Approach to Life
Body Size, Ecology, and Sociality of Mammals
Primate Evolution and the Emergence of Humans
The Impact of Humans on Other Species of Vertebrates