1 Ch4b: Overexploitation, Exotic Species, and Disease Species may be threatened even when habitat is intact Overexploitation is driven by globalization & technology Exotic species & diseases are widespread I. Overexploitation A. What is it? 1. overharvesting species 2. threatens endangered vertebrates B. Humans are ecologically efficient predators 1. traditional societies 2. globalization of markets 3. pets, décor, ornamentals 4. technology C. Particularly evident in oceans 1. many animals killed as “bycatch” 2. maximum sustainable yields may be unrealistic 3. overfished marine organisms 1946 – 1974 -- 1986 – D. Solutions? 1. regulations & CITES 2. national parks & nature reserves 3. link conservation & local economies. II. Exotic species A. Introduced accidentally or deliberately 1. desirable traits 2. repeat offenders: 3. most introductions are not successful 4. few exotics will harm their new environ. B. Introduction facilitated by2 1. loss of density-dependent factors 2. human altered environ. 3. “weedy” traits C. Impacts on native biota? 1. competition 2. predation 3. environmental degradation D. Endangered species in foreign lands E. Natives may become pests F. Few places free of exotics G. Islands are particularly vulnerable III. Spread of disease via A. Crowding B. Poor health from malnourishment C. Contact with domestic animals D. Human travel E. Global climate
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