Week 11- Ecological Disruptions
Week 11- Ecological Disruptions Biology 152
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This 2 page Class Notes was uploaded by BettyAnn Mead on Wednesday April 22, 2015. The Class Notes belongs to Biology 152 at University of Massachusetts taught by Peteh in Winter2015. Since its upload, it has received 97 views.
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Date Created: 04/22/15
Species interactions in communities 0 Each species interacts with many other species 0 Communities include complex webs of interactions among many species 0 Connections often revealed by unexpected outcomes when communities are disrupted Community dynamics revealed by disruptions Apex predator extirpation l Trophic cascade Deforestation l Vertebrate disease increase Invasive species l Lose of native biodiversity Trophic Levels and Ecological Pyramids Energy Flow 0 Energy is captured by primary producers 0 Usually photosynthetic organisms Consumers Primary consumer eat producers Secondary consumer eat primary consumer Tertiary consumer eat secondary consumer And so on Theory of Island Biogeography Predicts dynamic equilibrium of species on any particular island based on 0 Size of island 0 Distance from mainland source of species 0 Number of species on island determined by 0 Immigration Rate Species added 0 Extinction Rate Species subtracted Habitat Fragmentation Created habitat islands that are smaller and more isolated than the larger landscape they came from Minimum Critical Size of Ecosystems Project As forests are cleared in Brazil fragments of various sizes are preserved 1 10 100 1000 hectares Monitor diversity of selected groups over following years Minimum Critical Size of Ecosystems Project RESULT ONE In small fragments some bird and mammal species disappear Less dung and carrion Scarab beetles become more scarce Mites that infest beetles become scarcer Fewer mites means more ies More ies mean pathogens spread more rapidly Keystone Species A species whose importance to community is great relative to its abundance Often identi ed when removed Exotic and Invasive Species Communities can be disrupted by exotic species 0 Species introduced by humans to communities in which they were not previously found 0 Introduction can be intentional or unintentional 0 Have affected virtually all communities but especially problematic in disrupted habitats o Exotics often invasive 0 Native species often negatively affected Costs of Invasive More than 4500 foreign species have gained a permanent foothold or taken root in US during the past century Invasive species contribute to the decline of 46 of the imperiled or endangered species in the US Invasive species are estimated to cost a total of 137 billion annually in losses to agriculture forestry sheries and the maintenance of open water ways in the US Characteristics of Invasive Rapid population growth Displace or kill native species No natural population regulation 0 No predators o No pathogens High dispersal rate
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