G weeds 341 mammals eg rats cats feral pigs 371 birds

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Unformatted text preview: … 6 Globaliza8on: shipping   Major source of marine and fresh water introduc8ons o  o  Water ­filled ballast tanks Filled at port of origin, discharged at des8na8on Annual costs of damage and control of invasive species in the United States Annual cost of damage + control ($ billions) Type of organism Plants (e.g. weeds) 34.1 Mammals (e.g. rats, cats, feral pigs) 37.1 Birds (e.g. pigeons, starlings) 1.9 Fish 1.0 Arthropods (e.g. insects, crustaceans) 18.9 Mollusks (e.g. mussels, clams) 1.3 Microbes (e.g. pathogens, diseases) 41.1 Total >$136 billion per year! From Pimentel et al. 2000 8 Why are some introduced species so damaging?   Elevated impacts due to lack of coevolu8on with organisms in the invaded habitat Coevolu8on   The evolu8onary “arms race” – e.g. a bark beetle versus a conifer Host tree Herbivory e.g. conifer Herbivorous insect e.g. bark beetle Aggressive mandibles; aggregation pheromones Stone cells; resin ducts Induced resinosus; hypersensitive response Phytopathogenic fungal symbionts   Rela8onship becomes evolu8onarily “balanced” (unless perturbed by human ac8vi8es) Evolu8onarily unbalanced =   No long term “arms race”   Organisms in invaded habitat not adapted to invader   Ecological impacts amplified What makes a good invader? Trait Benefit Asexual reproduction No need to find a mate Fast g...
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