Biol2343-lecture-22-得克萨斯生态学课件

1、Chapter 55: Conservation Biology,Conservation biology A goal-oriented science that seeks to counter the biodiversity crisis, the current rapid decrease in Earths variety of life (Pg.1224) Biodiversity biological diversity,Three levels of biodiversity: Genetic diversity Species diversity Ecosystem di

2、versity,Some Benefits of Biodiversity (Pg.1227): Purification of air and water Reduction of the severity of droughts and floods Preservation of soils Detoxification of wastes Pollination of crops and natural vegetation Dispersal of seeds Nutrient cycling Moderation of weather extremes Provision of a

3、esthetic beauty,Example: Estimated ecosystem services per year: 33 trillion dollars (twice the GNP of the world!) 2)Biosphere II 200 million to build and it failed O2 concentrations dropped to 65% of Earths CO2 fluctuated widely Most vertebrate species went extinct Most pollinators died Explosion of

4、 pest species (roaches, etc.) What did we learn from this?,The biodiversity crisis is concerned with extinction,Is extinction a nature process?,Is extinction a nature process? YES!,Is extinction a nature process? YES! So, what about extinctions has scientists worried?,The RATE of Extinction,Rate Of

5、Extinction,time,10 mya 8 mya 6mya 4 mya 2 mya Present,Assessing Rates of Extinction: Species-Area relationship: the number of species in an area is directly related to the size of the area (we have seen this before!),As a result of the species-area relationship, rates of extinction are directly rela

6、ted to habitat loss,What are the major threats to biodiversity?,What are the major threats to biodiversity? 1) habitat destruction (Biggest Threat) 2) over exploitation of organisms 3) competition with exotic species 4) food chain disruptions,habitat destruction (Biggest Threat),Example of Habitat l

7、oss and Fragmentation in a Wisconsin Forest,over exploitation of organisms:,What are some examples of this?,Sport hunting of Whales and American Bison, Galapagos Tortoise 2) Harvested species: marine fishes, etc 3) Species killed by harvesting techniques: Dolphins 4) Pet trade species . Also leads t

8、o ,competition with exotic species,Examples of Introduced species,Nile perch,Brown Tree Snake,Argentine Ants,Seaweed, Caulerpa,All of these THREATS TO BIODIVERSITY can lead to small population sizes of native species or endanger already small populations. What are some consequences of small populati

9、on sizes?,What are some consequences of small population sizes?,The extinction vortex!,Increased rates of extinction leads to loss of biodiversity!,Why should we care about biodiversity? should we care?,?,Some reasons why biodiversity is important: Source of renewable resources Healthy environment (

10、to live in) Processing of critical elements like N, P, C 25% of all prescription drugs come from plants Animals and plants are a source of tremendous chemical diversity (drugs to fight cancer and disease) Genetic diversity (the backbone of adaptation!),The geographic distribution of biodiversity,Div

11、ersity Increases Toward The equator,Latitude,090,Species Diversity,Pattern of Species Diversity *latitudinal gradient*,Possible Explanations for latitudinal gradients in species diversity 1) Energy availability(increase photosynthesis) 2) Habitat Heterogeneity more local disturbances in tropics, inc

12、rease habitat patchiness 3) Niche specialization smaller niches 4) Population interactions coevolution limits species dominance in complex systems,There are also biodiversity Hot Spots these usually have a large number of endemic species (found nowhere else),Conservation at the population and specie

13、s levels (Pg.1232),Background terms: Endangered Species in danger of extinction through out all or a significant part of its range Threatened Species those species that are likely to become endangered in the foreseeable future through out all or a significant part of its range,What is a species?,Pro

14、blems of defining species has resulted in problems in trying to decide what needs protecting and what does not,Another problem in species level conservation is the fact that many species are distributed across patchy environments,metapopulation,The effect of man-made barriers,Metapopulation a subdiv

15、ided population of a single species,Source habitat: BD,Sink habitat: BD,A metapopulation,What might be a problem of trying to protect this species?,To think about: Can we protect everything? What should we focus on protecting? Is conservation important?,Conservation at the Community, Ecosystem, and

16、Landscape Levels Pg. 1238,Background: Past conservation efforts have focused on saving individual species, but current efforts are focused on protecting entire communities or ecosystems Current research is focusing on entire landscapes ecological landscape a regional assemblage of interacting ecosys

17、tems (Pg.1238) 3) Landscape Ecology is the application of ecological principles in the study of land-use patterns (Pg.1238),4) Understanding land use patterns is critical because: a) many species use more than one ecosystem b) species may live on the boarders between ecosystems,The goal of landscape

18、 ecology is to understand patterns of landscape use in the past, present, and foreseeable future and to make species conservation a functional part of the picture (Pg.1238),Edges and corridors can influence landscape biodiversity Edges the boundary between ecosystems (lake/forest edge) Movement Corr

19、idors a narrow strip or series of small clumps of quality habitat connecting otherwise isolated patches (Pg. 1238) Ex. Streamside habitats,How can humans and biodiversity coexist?,One way is to have sound management strategies,Gap Analysis (Pg. 1241),The Zoned Reserve Concept (Pg. 1241),Another way

20、humans can positively influence ecosystems is through Restoration Ecology (Pg. 1242) applies ecological principles in developing ways to return degraded ecosystems to conditions as similar as possible to their natural, pre-degraded state,Two key strategies of Restoration Ecology: Bioremediation is the use of living organisms, usually prokaryotes, fungi, or plants, to detoxify polluted ecosystems Augmentation determining what factors have been removed from an area and are limiting its recovery, and then aiding recovery by providing that factor or altering the environment to allow that factor t