envs 100 lecture 11

envs 100 lecture 11 - Key words for today • ...

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Unformatted text preview: Key words for today •  Ultimate, proximate drivers •  Biodiversity •  Ecosystem functions, processes •  Ecosystem services Key biodiversity questions •  What is biodiversity? •  Where is it concentrated? •  What are the major threats to biodiversity? •  What are key arguments to protect biodiversity? Biodiversity Edward O. Wilson: the totality of the inherited variation of all forms of life across all levels of variation, from ecosystem to species to gene Biodiversity Edward O. Wilson: the totality of the inherited variation of all forms of life across all levels of variation, from ecosystem to species to gene It is interesting to contemplate an entangled bank, clothed with many plants of various kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us…. from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved. Charles Darwin, The Origin of Species What is biodiversity not? •  The number of species (=species richness) •  Ecological processes •  Ecological functions •  Ecosystem services •  A common/ useful qualifier: “Native,” as in “native biodiversity” KINGDOM Animals Animals PHYLUM Chordates Arthropods CLASS Mammals Insects ORDER Primates Diptera FAMILY Hominids Muscidae GENUS Homo Musca SPECIES sapiens domestica How many species in the world? 1.5 million species described Discovery rate: 300 new species/ day Highest estimates: > 30 million Best guess: 5 ­15 million eukaryotes Erwin (1998, 1997): 136 unique beetle species per tree species x 50,000 tree species in the global tropics ~= 7 million beetle species Dirzo & Raven 2003. Annu. Rev. Environ. Resourc. 28:02 From Primack 2002, Essentials of Conservation Biology Number of described marine species climbs from 230,000 to 250,000 October 05, 2010 After a decade of research in oceans around the world, scientists released the final results of the first Census of Marine Life (CoML) on Monday. The research, which involved 2,700 scientists from more than 80 countries, increased the number of known marine species from 230,000 to 250,000. mongabay.com The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. New Giant Rat Discovered in Extinct Volcano September 7th, 2009 The Bosavi woolly rat (Mallomys sp.?). Photo courtesy of BBC Giant Rat ­Eating Plant Discovered By Explorers, Named After Famous Scientist First Posted: 08 ­17 ­09 05:46 PM | Updated: 09 ­17 ­09 05:12 AM Nepenthes attenboroughii (Phillippines) Given $10 billion/ year (the estimated global total assigned to biodiversity in any form), how would you focus biodiversity conservation effort? •  Where? •  Which drivers to tackle? •  Target: what scales? •  What more would you like to know in order to decide? Where are they? Global diversity is not evenly distributed. ~ 50% of the world’s species occur on 6 ­7% of the world’s land area. Where are they? 1) low latitudes Both regional diversity and site ­level diversity of species are highest in the tropics. Plants Dirzo & Raven 2003. Annu. Rev. Environ. Resourc. 28:02 Where are they? 2) islands Endemism: the proportion of taxa in a specified geographic area that is found nowhere else Islands: 3% of earth’s surface, but 15 ­20% of birds, reptiles and plants Dirzo & Raven 2003. Annu. Rev. Environ. Resourc. 28:02 Where are they (threatened)? 3) hotspots •  25 hotspots (plants, birds only) •  to qualify: high endemism, high threat www.biodiversityhotspots.org Myers et al. 2000. Nature 403: 853 Extinction: the fate of all species •  Only 2 ­3% of species that ever existed still exist today. •  How many extinctions? •  Is this too many? How many is too many? Famous extinctions Background extinction rates Fossil evidence: species typically last ~1 ­13 million years. (May, Lawton & Stork 1995) Molecular phylogenies: speciation rates are ~1 species/ million species ­years. Extinctions cannot historically exceed this. (Pimm et al. 1995) 0.1 – 1 extinctions/ million species ­years Current extinction rates: Birds For 10,000 species, at a rate of 0.25 extinctions/ million species ­years, we expect 1 extinction/ 400 years There have been 113 known bird extinctions in last 400 years. Cycads, 52% Threatened with extinction 23% Conifers, 25% 32% 12% Amphibians Chapin et al. 2000. Nature 405: 234 MEA 2005 Percent of species Consequences begin long before extinction Mammals: lost genetic, population diversity, functioning Ceballos and Ehrlich. 2001. Science 296:904 ­907 Intrinsic Utilitarian biodiversity ecosystem services What are consequences? • “Biological diversity is a necessary condition for the delivery of all ecosystem services…. Diversity is currently declining in most places in the world, along with the area of near ­natural ecosystems.” Millennium Ecosystem Assessment 2005 What are consequences? Ecosystem functioning, processes •  Energy and material flows – nutrient cycling, production •  Species interactions – seed dispersal, food sources •  Environmental conditions – climate, fire cycles •  Resistance to change – stability, resistance to invasions Ecosystem services The processes and conditions of natural ecosystems that support human activity and sustain human life Chapin et al. 2000. Nature 405: 235 How are changes in biodiversity and ecosystem functioning related? Chapin et al. 2000. Nature 405: 234 Biodiversity-ecosystem functionecosystem service linkages Chapin et al. 2000. Nature 405: 234 Ecosystem service trends “The supply of certain ecosystem services has increased at the expense of others. Significant gains in the provision of food and fiber have been achieved through habitat conversion, increased abstraction and degradation of inland waters, and reduced biodiversity…. • Declining trends in the capacity of ecosystems to render pollutants harmless, keep nutrient levels in balance, give protection from natural disasters, and control the outbreaks of pests, diseases, and invasive organisms are apparent in many places.” MEA 2005 Ultimate drivers? From R. Primack 2004 Ultimate drivers I = PAT Impact=Population x Affluence x Technology (Per capita consumption) Ehrlich & Ehrlich 1991 Proximate drivers 1. Habitat loss and degradation – affect 80 ­90% of threatened species 2. Direct exploitation – over 1/3 of threatened birds and mammals; many fishes 3. Invasive species – 30% of birds, 10 ­15% of mammals and plants 4. Pollution 5. (emerging) Climate change IUCN 2000 P AT Vitousek et al. 1997. Science 277: 494 ...
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This note was uploaded on 09/15/2011 for the course ENVS 100 taught by Professor Zavaleta,e during the Fall '08 term at UCSC.

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