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Global Biodiversity. Global Biodiversity Patterns and Processes

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  • Global Biodiversity

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and ProcessesWhat is Biodiversity?Biological diversity is the sum of all living thingsIt can be considered at many levels (e.g. genetic, regional, evolutionary lineage, number of ecosystems)Hierarchical perspective: genes, pop(s), species, communities, ecosystems, landscapes

  • Global BiodiversityPatterns and ProcessesGenetic DiversityGenetic diversity is the ultimate source of biodiversity at all levelsRecent advancements now allow us to measure (and quantify) genetic diversityImportant in establishing breeding programsMay allow species to broaden tolerances

  • Global BiodiversityPatterns and ProcessesGenetic DiversityConsider the use of genes in crops and livestockcan be either incorporating genes or just preserving existing breadthConsider Bt cotton: Bacillus thuringiensis (Bt) is a spore forming bacterium that produces crystals proteins, which are toxic to many species of insects.

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and ProcessesThere are trade-offs

  • Global BiodiversityPatterns and ProcessesPopulation-level DiversityThe variation within members of a species or population is extremely important (represents evolutionary history and is the source of potential future adaptations)Also provides a great deal of information about the amount and rate of gene flow between and among populations (more later)

  • Global BiodiversityPatterns and ProcessesIt is the local populations where environmental challenges occur and genetic diversity is maintainedConsider a species/population of corn that evolved in soil with high mineral (e.g. metals or salt) levelsThat population maybe become an invaluable crop species in some locations

  • Global BiodiversityPatterns and ProcessesGuppies in Trinidad streams have evolved without fish predatorsConsequently, they have very different life-history characteristics than species/populations exposed to predatorsIf a reintroduction or population supplementation is needed, knowledge of genetics and plasticity important

  • Global BiodiversityPatterns and ProcessesPopulations may also serve a functional role, which may be independent of other populationsE.g. pollinators

  • Global BiodiversityPatterns and ProcessesHuman Cultural DiversityConsider human cultural diversity and the reservoir of knowledge, skills, and traditions throughout the worldE.g. 6,526 distinct languages

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and ProcessesNon-random distribution of habitats

  • Global BiodiversityPatterns and ProcessesDiversity of SpeciesDespite many references to biodiversity and others at the species level (e.g. ESA, CITES) it is the populations that are as or more important (but not as easily comprehended by the public or politicians)

  • Global BiodiversityPatterns and ProcessesWhat is the difference between a species and population?Can be somewhat difficult to determine if they are one species or twoWhy? Problems: fossils, asexual organisms, lack of knowledgeIt is really a gradient

  • Global BiodiversityPatterns and ProcessesFor many bioinventories or rapid assements, may use concept of morphospeciesAs species (and populations) evolve, they continue to accumulate genetic differencesTo determine relatedness among these species (or pop(s)), biologists attempt to reconstruct phylogenies (more later)

  • Global BiodiversityPatterns and ProcessesBiological classification system based upon the idea of hierarchical organization and relatednessKing Phillip Came Over For Golf SaturdayShould always be a bifurcating tree

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and ProcessesHow many species are there?Approximately 1.75M named with another 300K fossil spOn average, 300 sp named each dayTwo new phyla have been named in past 25 yrsRange is 10M-50M

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and ProcessesFor starters, the immense richness of viruses, bacteria, archaea (singled-cell organisms in extreme environs), protists and other unicellular organismsOnly 80,000 fungi describedIn Britain, 6x fungi vs. vascular plantsExtrapolate worldwide, 1.6M fungiNematodes >200 sp in a few cm3

  • Global BiodiversityPatterns and ProcessesMites: 30,000 sp described (but probably >1M)Insects: almost 1M described, but consider canopy fogging4 sites
  • Global BiodiversityPatterns and ProcessesDiversity of higher taxaUntil recently, 5 kingdoms recognized

    PlantaeFungiMonera (bacteria)ProtistaAnimalia

  • Global BiodiversityPatterns and ProcessesToday, there is a recognized division among the prokaryotes and we have the Archaea and BacteriaGenetic diversity is as great as that across EukaryotesMany new kingdoms ascribed to Archaea, Bacteria, and ProtistsWhy care?

  • Global BiodiversityPatterns and ProcessesThey evolutionary lineage of each species is important for several reasons1) evolutionary potential relies on the diversity of life (many differences, albeit small)2) lineages are storehouses of info on the history of life3)functioning ecosystems depend upon the variety of life4) aesthetic benefits correlated with diversity

  • Global BiodiversityPatterns and ProcessesDiversity of biological communitiesThe composition of communities changes over time and spaceMembership within a community is probabilistic3 common metricsSp richness, evenness, abundanceFrequently compare metrics across habitats or sites (or genes)Could also use weighted measures

  • Global BiodiversityPatterns and ProcessesAre there limitations to using a metric like diversity?Species identitylose valuable information on functional role, exotic vs. native, life-history characteristicsBiological communities are of conservation interest because the relative abundances, combinations, +/- can all provide valuable information

  • Global BiodiversityPatterns and ProcessesEcosystem and Biome DiversityTypically terrestrial systems typically classified by shape and life-forms of the plants that dominate themHoldridges widely used life zone system is entirely based upon climatic variablesAlthough communities grade into one another, major divisions are useful for analyses and descriptions

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and ProcessesThings also change at relatively large scales based upon: latitude, altitude, and precipitation gradientsAt a finer scale, things change with soil type, slope, and species compositionRecently the WWF reclassified the Earths biomes into 867 terrestrial biomes (thought to represent distinct assemblages)

  • Global BiodiversityPatterns and ProcessesEcosystem approachManaging at the ecosystem allows for common goals across multiple owners and allows for large scale planning that is likely appropriate for even relatively large organisms

  • Global BiodiversityPatterns and ProcessesSpecies Richness over Geologic TimeThe number of species at any given moment represents the balance between extinction and speciation ratesThat number will vary according to the frequency and intensity of extinction and/or speciation events

  • Global BiodiversityPatterns and ProcessesThe fossil record shows a rough estimate of trends in species richness during the history of life on EarthCellular life began about 3.8 bya (bacteria) and eukaryotics probably about 2 byaThings were relatively quiet until the Cambrian explosion

  • Global BiodiversityPatterns and ProcessesFig 2.5 Diversity of marine families from Cambrian to present

  • Global BiodiversityPatterns and ProcessesTerrestrial plant appeared early in the Silurian and their richness increased rapidly during the DevonianThen during the Cretaceous, another important event occurred, the appearance of angiospermsHad cascading effects

  • Global BiodiversityPatterns and ProcessesFig 2.6Each group, ferns, gymnosperms and angiosperms, have all dominated at one time

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and ProcessesRates of species formationSpeciation rates are not consistentWhen do you think it accelerates?

  • Global BiodiversityPatterns and ProcessesRates of species formationThe first was the Cambrian (500mya) Second Paleozoic (440mya)The third set diversity way back in Permian (250mya), followed by Triassic explosion

  • Global BiodiversityPatterns and ProcessesCambrian: all major groups of living organisms appeared during this time (and some that did not make it)Paleozoic and Triassic greatly increased families, genera and species, but no new phyla emerged

  • Global BiodiversityPatterns and ProcessesFactors impacting rates of speciationAny guesses?Mass extinctionsIncreasing separation of landmassesNew species and species interactions

  • Global BiodiversityPatterns and ProcessesDiversity explosions throughout the ages

  • Break-up of Pangea in Laurasia ad Gondwanaland followed by more isolation

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and ProcessesRates of ExtinctionSimilarly, rates vary throughout time6 major events60% 75% 95% 65% 75% **

  • Global BiodiversityPatterns and ProcessesAlthough species generally recovered, there is a lag of about 10myThe major impact of mass extinctions events has been to eliminate some lineages while opening ecological niches for others

  • Global BiodiversityPatterns and ProcessesCurrent patterns of species richnessDiversity is not spread evenly

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and ProcessesTo properly preserve species, it is important to know where species occurOne such tool is a GISAnother useful approach is to divide species richness into major componentsAlpha-richness (small homogeneous area)Beta (rate of change across communities)Gamma (changes across larger landscapes)

  • Global BiodiversityPatterns and ProcessesHigh generally means many rare spHigh means the cumulative number of species recorded rapidly increases as additional areas are censused along some environmental gradientHigh may result from having many different types of habitats within a larger landscape and each of those habitats having some unique members

  • Global BiodiversityPatterns and ProcessesSpecies turnover for birds in Mediterranean

  • Global BiodiversityPatterns and ProcessesDifferentials of turnover curves

  • Global BiodiversityPatterns and ProcessesPatterns of EndemismEverything is endemic at some scaleThere are areas of high endemism, usually resulting from isolation (e.g. islands, large dispersal barriers)Areas of endemism are usually not associated with areas of high diversityWhy?

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and ProcessesPatterns of EndemismNot surprisingly, patterns of endemism differ greatly across taxaFor example, SAf and sw Aust have very high levels of plant endemism, but not animalsHowever, there are correlates for endemism among vertebrates

  • Global BiodiversityPatterns and ProcessesMarine diversity (damselfish)Indo- Pacific a hotspot

  • Global BiodiversityPatterns and ProcessesLatitudinal Gradient in Species RichnessIn both terrestrial and marine environments, tropical regions have more species than temperate ones for many (or most) all taxonomic groupsExceptions: marine birds and mammals, seaweeds, salamanders

  • Global BiodiversityPatterns and ProcessesBivalve mollusks

  • Global BiodiversityPatterns and Processes

  • Global BiodiversityPatterns and ProcessesAlthough the pattern is widespread, the mechanism (process) generating it remains in questionAdditionally, it is likely that different groups have different combinations of factors determining their distribution

  • Global BiodiversityPatterns and ProcessesSpecies-area CurveOne of the first ecological relationships established empirically was the relationship between area and number of species

    S is species number, A is area, z represents how quickly species are accumulated and c is a constantS=cAz

  • Global BiodiversityPatterns and Processesz varies across taxonomic groups and habitatsE.g. relatively low values 0.15 on oceanic islands to 0.25 to 045 for continents

  • Global BiodiversityPatterns and ProcessesReptiles and amphibians

  • Global BiodiversityPatterns and ProcessesLandbirds and freshwater birds in SE Asia

  • Global BiodiversityPatterns and ProcessesOne confounding factor is the relatively large area of the tropicsConsequently, is the higher diversity in the tropics a result of simply larger areas?What other factors may contribute to higher diversity in the tropics?

  • Global BiodiversityPatterns and ProcessesSpecies Richness-energy RelationshipsSimply the more energy that is available the more biomass enables more individuals (hence species) to coexistIn tropics, even less energy used to maintain oneselfHigher productivity can also allow for dietary specialization

  • Global BiodiversityPatterns and ProcessesEvidence for these patterns are not consistentE.g. strong correlation between annual evapotranspiration and tree sp richness in NAmE.g. some of the most productive ecosystems (estuaries, hotsprings, seagrass beds) are species-poorLook at relationship between soil fertility, plant richness & seed dispersers

  • Global BiodiversityPatterns and ProcessesMarine systems: richness and depththe paradox of enrichmentSp do well in either fresh or saltwater

  • Global BiodiversityPatterns and ProcessesEnergy may also influence richness indirectly through increases habitat complexity (structure)Habitat complexity and richness is generally positive for a wide-ranging group of organisms (think birds in grasslands vs. forests)Conversely, think about lizard richness in the desert

  • Global BiodiversityPatterns and ProcessesDisturbance and Species RichnessEasy to understand how large climatic variation could reduce sp richnessMore poleward populations are impacted by remaining individuals having characteristics that favor lower speciation rates (less specialization, larger ranges and greater vagility)

  • Global BiodiversityPatterns and ProcessesDisturbance and Species Richness

  • Global BiodiversityPatterns and ProcessesDisturbance and RichnessPhysical disturbances can influence local richness by destroying habitat, selectively (or not) killing individuals, and sterilizing soilsConsider a constant environment, what should this lead to? Why?

  • Global BiodiversityPatterns and ProcessesIntermediate Disturbance Hypothesis

  • Global BiodiversityPatterns and ProcessesConsider the rocky intertidal communities of the Pacific Coast Pisaster ochranceus feeds on the competitively dominant mussel Mytilus californianusWhen it is removed, allows less competitive individuals to become established on the rocks

  • Global BiodiversityPatterns and ProcessesIntermediate Disturbance Hypothesis

  • Global BiodiversityPatterns and ProcessesInteractions between local and regional species richnessLocal species richness can strongly be influenced by local interactions and process operating at larger spatial and temporal scales (e.g. dispersal, speciation, historical biogeography)Ultimately, are there limits to community numbers?

  • Global BiodiversityPatterns and ProcessesIs it limited by niche overlap?Does the chemical warfare between plants and herbivores set limits to sp richness or does it promote speciation?Are there limits to the size of mimicry systems and do mimicry systems allow for more or less species to coexist?Has the richness generated by plant-pollinators been reached? Seed dispersers?

  • Global BiodiversityPatterns and ProcessesImportance of BiodiversityMerit vs. money?Many examples of ecosystem services

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  • Global BiodiversityPatterns and ProcessesImportance of BiodiversityMerit vs. money?Many examples of ecosystem servicesHowever, it is not clear what the relationship between ecosystem function and species richnessImportance of rare species, which are most common, is poorly understood

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  • Global BiodiversityPatterns and ProcessesIncreasingly there are opportunities for researchers to test some ecosystem theory at very large spatial scales

  • Global BiodiversityPatterns and ProcessesBiological dynamics of forest fragment project (Manaus, Brazil)

  • Global BiodiversityPatterns and ProcessesCalling Lake fragmentation exp (Canada)

  • Global BiodiversityPatterns and ProcessesSavannah River Corridor Project

  • Global BiodiversityPatterns and ProcessesFuture of Biodiversity StudiesNeed to generate many more taxonomists; especially in tropical countries and in groups poorly studied

  • Global BiodiversityPatterns and ProcessesE.O. Wilson: 50yr inventoryRapid Assessment Program: focus on areas of high endemism and diversityGroups of experts on the better known groups (e.g. butterflies, birds, flowers)Establish research stations in same areaCombine RAP and intensive studies from research stations

  • Global BiodiversityPatterns and ProcessesContinue phylogenetic studiesFurther examinations on anthropogenic stresses on the environmentMillennium Ecosystem Assessment: a multi-agency, governmental coalition of international development and conservation organizations, and scientists to assess the status the Earths ecosystemsHope is to help focus research on the connections between the status of biodiversity and ecosystem services

  • Global BiodiversityPatterns and ProcessesMEA

  • Global BiodiversityPatterns and ProcessesThe end of chap 2