Transcript Ecology
Ecology The scientific study of the distribution and abundance of organisms and the interactions that determine distribution and abundance Begon, Harper, Townsend, 2006, Ecology, Blackwell Ecology is the scientific study of the distribution and abundance of organisms and the interactions that determine distribution and abundance Lecture outline 1. The evolution of life and life histories 2. The flux of energy and matter 3. Individuals and populations 4. Ecological communities 5. Positive and negative species interactions 6. Trophic networks 7. Distributions in time 8. Distributions in space 9. Function and diversity 10. The human impact Literature Literature Ecological slideshows http://www.slideshare.net/marglema9/ecol ogy-1 Ecological e-books http://www.ebooksdownloadfree.com/d ownload/ecology-1.html The scientific study of the distribution and abundance of organisms and the interactions that determine distribution and abundance The scientific method Deduction Top down logic Theory Theory Hypotheses Testable predictions Hypothesis modification Hypotheses Testable predictions Observations Hypothesis testing Observations Induction Bottom up logic A theory is used as a testable set of logically coherent hypotheses Hypothesis are assumed of being falsifiable The core of a theory is difficult to falsify because it can always be modified in a way to match empirical observations In the natural sciences we often do not test theories. We treat theories as an expectation under predefined conditions and are interest in the deviation of reality from expectation. Theory Observations Modify the theory to match observations Modify theory The core of any theory is hard to falsify. Difference too large Difference (Residual) It is impossible to veryfy the core. Conditions of the theory not met The new hypotheses do not directly follow from our theory. They contain an empirical element. Hypotheses, testable predictions In this case the theory becomes untestable and therefore unfalsifiable. Theory predicts the number of insect species to rise to the power of 5/4 with plant species richness We use c2 or Kolmogoroff Smirnoff tests to infer whether the theory matches the data. Residual ππππ πππ‘ = ππππππ‘ 5/4 Often these formal tests will reject the theory. Gaston 1992 We do not test the theory. We use the theory and the empirical data to study additional factors. We calculate the residuals and regress them with the area under study. We detect four areas with much too low and one area with too high species richness of insects. What is ecology? The term ecology was coined 1866 by Ernst Haeckel in his habilitation lecture. Oikos: home Ecology deals with patterns and with processes in the living world. Aims of ecology: Ernst Haeckel (1834-1919) Describing the place of living beings in their environment Explaining abundances, distributions, and interactions of living beings Predicting the changes in the abundance and distribution of living beings Controling changes in the abundance and distribution of living beings Autecology deals with the life history of single species Population ecology deals with the abundance and distribution of a group of interbreeding organisms Community ecology deals with a group of interacting species Evolutionary ecology deals with the evolutionary history of todays ecological systems The basic units of ecological research are Genes Individuals Populations Species The scientific study of the distribution and abundance of organisms and the interactions that determine distribution and abundance Distribution and abundance might relate to genes, individuals, populations, or species The manifold of genes or species is called diversity. Applied to all living beings we speak of biodiversity Charles Robert Darwin (1809-1882) Alfred Russel Wallace (1823-1913) Number of marine families 2500 N u m b e r o f fa m ilie s z M as s e xtinc tio ns 2000 1500 1000 500 0 -6 0 0 -5 0 0 E K -4 0 0 O S D -3 0 0 C P -2 0 0 T -1 0 0 J Kr 0 Pa N Allopatric , peripatric, and sympatric speciation Allopatric speciation is generally slow Spatial breeding barrier Species home range Peripatric speciation might be fast Time Allopatric and peripatric speciation: New species emerge by genetic divergence in geographically isolated regions Sympatric speciation: New species emerge within the same habitat by any other breeding barrier. The include behavioural, resource use, or morphological barriers. The diversification of species Tinamou South Amercia / Africa Ostrich Rhea Spotted Kiwi Great Kiwi North Island Kiwi South Island Kiwi Cassowary New Zealand Australia 80 Time Tinamou Rhea Emu 0 Cassowary Low diversity of nine species Comparably high genetic diversity Todayβs biodiversity is largely caused by evolutionary history and plate tectonics Zosterops poliogaster Zosterops abyssinicus Postglacial colonization of Europe During the last 10,000 years Central and Northern Europe was recolonised from multiple glacvial refuges where species survived the ice age. We reconstruct colonisation routs by the analysis of genetic diversity across Europe. Because colonising populations are often small they are generically impoverished (founder effect). The refuges are centres of gentic diversification. Major refuges where: The Maghreb Spain Turkey Sicily Cyrpus Crete Hewitt G.M. 1999. Postglacial recolonisation of European biota. Biol. J. Linn. Soc. 68: 87-112. Postglacial colonization of Europe Carabus auronitens Colonisation gradient Founder effects Ordered genetic loss Populations Relict populations Vicariant (scattered) genetic loss Colonisation gradient The allele - sites matrix is sorted according to allele richness Postglacial colonisation of European Tenebrionidae (Coleoptera) Reconstruction of postglacial colonisation using phylogenetic relatedness of species Three major postglacial refuges with high numbers of endemics and high rates of glacial speciation Three major colonisation routes Past and present fragmentation Distribution of South American rainforest refugia (100,000 to 20,000 BP) based on the overlap of postulated refugia for birds, butterflies and plants. Shading represents probability of locations being refugial. Whitmore, T.C. ,Prance, G.T. 187. Biogeography and Quaternary History in Tropical America. Blackwell. Convergent evolution by similar selective pressures Ecological niches Charles Elton, 1900-1991 Joseph Grinnell, 1877-1939 The niche is the role a species plays in a community, rather than a habitat. The niche is the sum of the habitat requirements that allow a species to persist and produce offspring. Profession G Evelyn Hutchinson, 1903-1991 The niche is an n-dimensional hypervolume, where the dimensions are environmental conditions and the resources that define the requirements of an individual or a species to practise Two niche dimensions of a plant Optimum Suboptimum Water A given habitat filters species according to the abiotic conditions Performance Light Place Performance of a species Reproduction Growth Survival Condition Performance Specialist species Generalist species Condition Ecological niches emerge from differences in performance along the gradient of habitat conditions Formally a niche is the place of a species within a multidimensional hypervolume spanned by all resources used by this species. Generalist species have relatively broad niches in comparison to specialist species. Performance A habitat is the place where a species occurs. Do not mismatch habitat and niche! Realized niche Fundamental niche Condition The carbon isotope ratio of body tissues (13C β 12C = Ξ΄13C) depends on resource width, while the nitrogen isotope ratio (15N β 14N = Ξ΄15N) increases in insects with trophic level. Ground beetles (Carabidae) on Mazurian lake islands Trophic position top basal Error bars denote a standard error Zalewski et al. 2013, Ann.Zool.Fenn Number of resources Parts of the species are well segregated in trophic niche space, while another part of species highly overlaps in resource use. The plot shows also three different guilds of species with similar resourse use. The basic resources of life Carbon source Proton source (CH2O)n (CH2)nH2 Heterotroph CA Autotroph CO2 Organotroph + D--H+ + Lithotroph Water, Hydrocompounds Energy storage Energy Organic compounds Electron acceptor Energy storage Facultative store of energy excess Light Phototroph E + S β (CH2O)n + DA + ES Reduction Oxidation Organic compounds Waste Chemotroph Chemical reaction 6CO2 + 6H2O + light + ADP β C6H12O6 + 6O2+ ATP Green plants, Cyanobacteria C6H12O6 + C6H12O6 + O2 + ADP β (CH2O)n + CO2 + H2O + ATP Animals, fungi CO2 + NH3 + O2 + ADP β (CH2O)n + HNO2 + H2O ATP Nitrosomonas bacteria Resources and feeding types Energy source Electron donator Organic (Organo) Light (Photo) Inorganic (Litho) Radioactivity Inorganic (Litho) Organic (Organo) Chemical compound (Chemo) Inorganic (Litho) Carbon source Trophic group Organic (Hetero) Photoorganoheterotrophs Inorganic (Auto: CO2) Photoorganoautotrophs Organic (Hetero) Photolithoheterotrophs Inorganic (Auto: CO2) Photolithoautotrophs Cyanobacteria, green plants Inorganic (Auto: CO2 Radiolithoautotrophs Firmicutes heat tolerant Eubacteria Organic (Hetero) Chemoorganoheterotrophs Animals, fungi, green plants Inorganic (Auto: CO2) Chemoorganoautotrophs Spirochaetes Organic (Hetero) Chemolithoheterotrophs Inorganic (Auto: CO2) Chemolithoautotrophs Purple non-sulfur bacteria Iron bacteria, Archaea Trophic niche spaces in eukaryotes The specific trophic needs of organisms define their trophic niche. Trophic niches are generally not species specific. They are highly variable in time and space. Animals Carnivores Green plants Producers Latin Greek Herbivore Carnivore Fungivore Omnivore Saprovore Microvore Bacteriovore Phytophage Zoophage Mycetophage Pantophage Saprophage Microphage Bacteriophage Herbivores Parasites Fungivores Omnivores Mineralisers Saprovores Fungi, slime moulds, animals Omnivores are animals that feed on other animals and plants