history of Conservation in the US lecture 3b

history of Conservation in the US lecture 3b - History of...

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Unformatted text preview: History of conservation History of conservation in the US (part 3) Early regulation and preservation of wildlife Early regulation and preservation of wildlife 1900­ The Lacey Act of 1900 (the Lacey Act) Prohibits the illegal capture and limits the transportation of wildlife across state lines 1934­ The Migratory Bird Hunting Stamp Act Federal hunting stamp funds used for conservation of wetlands 1937­ Pittman­Robertson Wildlife Restoration Act 11% tax on all hunting equipment, funds used to restore and protect wildlife habitats Timeline of US Conservation Timeline European settlement to 1850: The endless American Wilderness 1850­1900: “Unregulated” exploitation and depletion of natural resources 1880­1932: Early regulation and preservation 1920­1960: The “golden age” of resource management 1960­present: The modern environmental movement Rachel Carson 1907­1964 The birth of the environmental The birth of the environmental movement Trained as marine biologist Nature writer 1950’s wrote 3 books about marine biology Silent Spring (1962) examined The Seas Around Us (1951) environmental problems caused by synthetic pesticides (e.g., DDT)­ why would spring be silent? No more birds!!! A maturing Science: A maturing Science: ecology embraces complexity Robert MacArthur (1930­1972) Student of Hutchinson (niche) Mathematical genius E. O. Wilson (1929­ present) Harvard professor Many books A maturing Science: A maturing Science: ecology embraces complexity Robert MacArthur (1930­1972) The Theory of Island Biogeography (1967) E. O. Wilson (1929­ present) The species area relationship The species area relationship Smaller islands “tend” to have fewer species than larger islands The relationship was recognized early- 1920’s The species area relationship This relationship can be illustrated in a graph called the “species area curve” Nearly universal phenomena in nature Applies to sampling efforts Habitat size The species area relationship All other factors being equal, larger areas will contain more species The species area relationship The species area relationship The species area relationship The species area relationship 0 20 0 18 25 92 33 17 31 22 36 49 0 41 112 84 18 26 15 15 0 37 31 51 14 23 40 28 16 72 103 12 23 104 32 21 14 21 50 29 8 35 70 30 24 16 4 0 6 0 71 19 15 8 1 21 10 10 13 0 10 18 21 13 15 23 10 10 249 0 9 9 10 15 12 5 0 7 0 7 9 0 9 10 9 8 9 13 9 3 12 7 4 4 4 3 10 10 7 3 10 9 8 9 5 3 0 5 9 5 1 4 16 6 7 11 8 0 11 10 8 4 3 7 3 7 13 0 14 7 8 13 41 57 Samp le e f fo rt (effo rt mea sured a s numb er o f u ni que sample loca ti ons per cou nt y) Taxa ricness (number of unique taxa per county) Data bas ed o n NMNH cray fis h co lle ction rec ords The species area relationship The species area relationship AL Taxa richness vs Sample Effort (Species/Area) 30 25 20 Taxa richness R2 = 0.6311 15 10 5 0 0 20 40 60 80 100 120 140 160 180 200 -5 Number of unique sample locations per county The species area relationship The species area relationship Smaller islands “tend” to have fewer species than larger islands But distance from mainland seemed to have an effect So what is going on? The species area relationship The species area relationship Smaller islands “tend” to have fewer species than larger islands But distance from mainland seemed to have an effect How do species get on an island? Immigration (but given enough time adaptive radiation may occur) Immigration and isolation Immigration and isolation Immigration, isolation, speciation Immigration, isolation, speciation Vacant niches Species (#) Im gra mi Rate ­ Sp ec Isolation + ­ Isolation Sp ec eff iati ec o n t iat n ti o ion + The species area relationship The species area relationship Smaller islands “tend” to have fewer species than larger islands But distance from mainland seemed to have an effect Given immigrationWhy are species numbers constant? Extinction (extirpation) Extinction and population size Extinction and population size The smaller the population the greater the likelihood of extinction Populations are limited by space­ smaller areas smaller populations Density independent factors (e.g., storm) Density dependent factors (e.g., new predator, competitor) The species area relationship The species area relationship Smaller islands “tend” to have fewer species than larger islands But distance from mainland seemed to have an effect Immigration Extinction (extirpation) The Theory of Island Biogeography (1967) + Immigration Rate ­ ­ Number of species + The Theory of Island Biogeography (1967) + Immigration Extinction Rate ­ ­ Number of species + The Theory of Island Biogeography (1967) The equilibrium point + Immigration Extinction Rate ­ ­ Number of species + The Theory of Island Biogeography (1967) + Immigration Large island Small island Extinction Rate Small island ­ ­ Number of species + The Theory of Island Biogeography (1967) + Immigration Large island Small island Extinction Rate Small island Large island ­ ­ Number of species + + The Theory of Island Biogeography (1967) The equilibrium point Immigration Large island Small island Extinction Rate Small island Large island ­ ­ Number of species + Two greatest conservation threats Two greatest conservation threats today (global) Climate change­ recently recognized 1970’s Habitat loss and fragmentation­ has accelerated in the recent past, but has been the center of conservation in the US The Theory of Island Biogeography and conservation The evils of habitat fragmentation + Immigration Large habitat fragment Extinction Rate Small habitat fragment Small habitat fragment Large habitat fragment ­ ­ Number of species + Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation Trends in habitat fragmentation fragments are islands Immigration/recolonization Extinction/extirpation Trends in habitat fragmentation Trends in habitat fragmentation Immigration/recolonization Extinction/extirpation Edge effect- Functional habitat may be reduced to core areas Trends in habitat fragmentation Trends in habitat fragmentation Immigration/recolonization Extinction/extirpation Edge effect- Functional habitat may be reduced to core areas High species (#) Low species (#) Why is habitat fragmentation such an issue Why is habitat fragmentation such an issue in the current global extinction crisis Smaller habitat patch Reduced function­ small sizes exclude large scale processes Isolates populations Reduced population sizes­ increased likelihood of extirpation Each isolated population is independent­ results in increased overall extinction risk Island biogeography and conservation Island biogeography and conservation Identify conservation priorities Identify restoration priorities Reserve design Reserves should be as large as possible High priority biota should have multiple reserves Preserve shape is important ...
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