Global Biodiversity - Introduction to Conservation Biology - Lecture Slides, Slides of Biology

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Global Biodiversity Docsity.com Global Biodiversity Patterns and Processes • What is Biodiversity? • Biological diversity is the sum of all living things • It can be considered at many levels (e.g. genetic, regional, evolutionary lineage, number of ecosystems) • Hierarchical perspective: genes, pop(s), species, communities, ecosystems, landscapes Docsity.com Global Biodiversity Patterns and Processes • Population-level Diversity • The 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) Docsity.com Global Biodiversity Patterns and Processes • It is the local populations where environmental challenges occur and genetic diversity is maintained • Consider a species/population of corn that evolved in soil with high mineral (e.g. metals or salt) levels • That population maybe become an invaluable crop species in some locations Docsity.com Global Biodiversity Patterns and Processes • Guppies in Trinidad streams have evolved without fish predators • Consequently, they have very different life-history characteristics than species/populations exposed to predators • If a reintroduction or population supplementation is needed, knowledge of genetics and plasticity important Docsity.com Global Biodiversity Patterns and Processes • Diversity of Species • Despite 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) Docsity.com Global Biodiversity Patterns and Processes • What is the difference between a species and population? • Can be somewhat difficult to determine if they are one species or two… • Why? • Problems: fossils, asexual organisms, lack of knowledge It is really a gradient Docsity.com Global Biodiversity Patterns and Processes • For many ‘bioinventories” or rapid assements, may use concept of ‘morphospecies’ • As species (and populations) evolve, they continue to accumulate genetic differences • To determine relatedness among these species (or pop(s)), biologists attempt to reconstruct phylogenies (more later) Docsity.com Global Biodiversity Patterns and Processes • For starters, the immense richness of viruses, bacteria, archaea (singled-cell organisms in extreme environs), protists and other unicellular organisms • Only 80,000 fungi described • In Britain, 6x fungi vs. vascular plants • Extrapolate worldwide, 1.6M fungi • Nematodes >200 sp in a few cm3 Docsity.com Global Biodiversity Patterns and Processes • Mites: 30,000 sp described (but probably >1M) • Insects: almost 1M described, but consider canopy fogging • 4 sites <70km proximity, 1% common 55% Docsity.com Global Biodiversity Patterns and Processes • Diversity of higher taxa • Until recently, 5 kingdoms recognized Plantae Fungi Monera (bacteria) Protista Animalia Docsity.com Global Biodiversity Patterns and Processes • Diversity of biological communities • The composition of communities changes over time and space • Membership within a community is probabilistic • 3 common metrics – Sp richness, evenness, abundance • Frequently compare metrics across habitats or sites (or genes) • Could also use weighted measures… Docsity.com Global Biodiversity Patterns and Processes • Are there limitations to using a metric like diversity? – Species identity…lose valuable information on functional role, exotic vs. native, life- history characteristics • Biological communities are of conservation interest because the relative abundances, combinations, +/- can all provide valuable information Docsity.com Global Biodiversity Patterns and Processes • Ecosystem and Biome Diversity • Typically terrestrial systems typically classified by shape and life-forms of the plants that dominate them • Holdridge’s widely used life zone system is entirely based upon climatic variables • Although communities grade into one another, major divisions are useful for analyses and descriptions Docsity.com Global Biodiversity Patterns and Processes • Species Richness over Geologic Time • The number of species at any given moment represents the balance between extinction and speciation rates • That number will vary according to the frequency and intensity of extinction and/or speciation events Docsity.com Global Biodiversity Patterns and Processes • The fossil record shows a rough estimate of trends in species richness during the history of life on Earth • Cellular life began about 3.8 bya (bacteria) and eukaryotics probably about 2 bya • Things were relatively quiet until the ‘Cambrian explosion’ Docsity.com Global Biodiversity Patterns and Processes • Terrestrial plant appeared early in the Silurian and their richness increased rapidly during the Devonian • Then during the Cretaceous, another important event occurred, the appearance of ‘angiosperms’ • Had ‘cascading effects’ Docsity.com Global Biodiversity Patterns and Processes • Rates of species formation • The first was the Cambrian (500mya) • Second Paleozoic (440mya) • The third set diversity way back in Permian (250mya), followed by Triassic explosion Docsity.com Global Biodiversity Patterns and Processes • Cambrian: 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 Docsity.com Global Biodiversity Patterns and Processes • Factors impacting rates of speciation • Any guesses? – Mass extinctions – Increasing separation of landmasses – New species and species interactions Docsity.com Global Biodiversity Patterns and Processes • Although species generally recovered, there is a lag of about 10my • The major impact of mass extinctions events has been to eliminate some lineages while opening ecological niches for others Docsity.com Global Biodiversity Patterns and Processes • Current patterns of species richness • Diversity is not spread evenly Docsity.com Global Biodiversity Patterns and Processes • To properly preserve species, it is important to know where species occur • One such tool is a GIS • Another useful approach is to divide species richness into major components – Alpha-richness (small homogeneous area) – Beta (rate of change across communities) – Gamma (changes across larger landscapes) Docsity.com Global Biodiversity Patterns and Processes • Differentials of turnover curves Docsity.com Global Biodiversity Patterns and Processes • Patterns of Endemism • Everything is endemic at some scale • There 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 diversity • Why? Docsity.com Global Biodiversity Patterns and Processes • Patterns of Endemism • Not surprisingly, patterns of endemism differ greatly across taxa • For example, SAf and sw Aust have very high levels of plant endemism, but not animals • However, there are correlates for endemism among vertebrates Docsity.com Global Biodiversity Patterns and Processes • Although the pattern is widespread, the mechanism (process) generating it remains in question • Additionally, it is likely that different groups have different combinations of factors determining their distribution Docsity.com Global Biodiversity Patterns and Processes • Species-area Curve • One 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 constant S=cAz Docsity.com Global Biodiversity Patterns and Processes • z varies across taxonomic groups and habitats – E.g. relatively low values ≈0.15 on oceanic islands to 0.25 to 045 for continents Docsity.com Global Biodiversity Patterns and Processes • Evidence for these patterns are not consistent – E.g. strong correlation between annual evapotranspiration and tree sp richness in NAm – E.g. some of the most productive ecosystems (estuaries, hotsprings, seagrass beds) are species-poor • Look at relationship between soil fertility, plant richness & seed dispersers Docsity.com Global Biodiversity Patterns and Processes • Marine systems: richness and depth • ‘the paradox of enrichment’ • Sp do well in either fresh or saltwater Docsity.com Global Biodiversity Patterns and Processes • Energy 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… Docsity.com Global Biodiversity Patterns and Processes • Consider the rocky intertidal communities of the Pacific Coast • Pisaster ochranceus feeds on the competitively dominant mussel Mytilus californianus • When it is removed, allows ‘less’ competitive individuals to become established on the rocks Docsity.com Global Biodiversity Patterns and Processes « Intermediate Disturbance Hypothesis Diversity Low High Disturbance frequency or intensity PRONCIPLES OF CONBERYATION 4HOK OG", Me ation Figure: 18 ©2008 Sacer Ausacems, Docsity.com Global Biodiversity Patterns and Processes • Interactions between local and regional species richness… • Local 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? Docsity.com Global Biodiversity Patterns and Processes • Importance of Biodiversity • Merit vs. money? • Many examples of ecosystem services • However, it is not clear what the relationship between ecosystem function and species richness • Importance of rare species, which are most common, is poorly understood Docsity.com Global Biodiversity Patterns and Processes • Increasingly there are opportunities for researchers to test some ecosystem theory at very large spatial scales Docsity.com Global Biodiversity Patterns and Processes • Biological dynamics of forest fragment project (Manaus, Brazil) Docsity.com Global Biodiversity Patterns and Processes • Future of Biodiversity Studies • Need to generate many more taxonomists; especially in tropical countries and in groups poorly studied Docsity.com Global Biodiversity Patterns and Processes • E.O. Wilson: 50yr inventory • Rapid Assessment Program: focus on areas of high endemism and diversity – Groups of experts on the better known groups (e.g. butterflies, birds, flowers) • Establish research stations in same area • Combine RAP and intensive studies from research stations Docsity.com Global Biodiversity Patterns and Processes • Continue phylogenetic studies • Further examinations on anthropogenic stresses on the environment • Millennium Ecosystem Assessment: a multi- agency, governmental coalition of international development and conservation organizations, and scientists to assess the status the Earth’s ecosystems • Hope is to help focus research on the connections between the status of biodiversity and ecosystem services Docsity.com