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双语教学课程 Bilingual teaching program Lecture notes for Paleoecology Instructor: Hong HUA (华 洪) Email: [email protected] Office: Room 430, Geological building Scientific Method When solving problems scientifically we follow a series of steps to avoid wasting time, effort, and resources. These steps include: 1. Defining the ________ (may include research or observation) 2. Stating a ____________ (explanation of observation; must be able to be tested) 3. _________ the hypothesis (involves measurement of one variable at a time) 4. Analyzing the _________ (data organized in graphs, tables, and charts) 5. Drawing _____________ (returning to step #2 as needed) ***This is not a rigid, step-by-step outline.*** Schedule of Topics Topic Introduction The Earth as a system How Real is Global Warming? Cultural Responses to Climate Change: What we have learnt from the Holocene Gigantism & Dwarfism: Thoeries about biogeography The modern-Day Mass Extinction: Lessons from the past Invasive Species: What’s the Problem All things are not equally nice to eat: Evolutionary Patterns The Panda’s thumb: Functional morphology Trace Fossils : Reconstructing Animal Behavior Evolutionary Paleoecology Examinations and Grading: Grading: 1 tests at 70 points plus 1 presentations at 30 points Presentation will be evaluated by the instructor and by the students:20 points By Instructor and 10 points by Average of student evaluations Final examination: l Writing test for 3 hours; l Open to textbooks, dictionary and any other material. l Questions and answer are in English Topic 1 Introduction • 1. What is Paleoecology? • 2. The data base in paleoecology • 3. The operational base in paleoecology • 4. The nature of the fossil record Study of fossils What? What are fossils? Morphological paleontology When? When did a particular fossil live? Stratigraphical paleontology Whence(从何处来) and whither(到何处去)? in other words, what were the ancestors of a particular fossil and what were its descendants? Evolutionary paleontology How and where? How and where animals and plants lived in the past ? Paleoecology 岩石地层学 古环境学 地史学 化石 古生物学 生物地层学 古生态学 古生物钟 地质年代学 古生物地理学 进化生物学 生物化石在地质学科多方面的运用 1. What is Paleoecology? Ecology is the study of the interactions of organisms with one another and with the physical environment Paleoecology is the study of the environmental relationships of organisms in the geological past • “ecology of the past” where our understanding of the “present is the key to understand the past” • Theory = paleoecology is the understanding of relationships between past organism and the environment in which they lived • Practice = paleoecology is the practice of reconstruction of past environments Two dominant subject areas in paleoecology ●The study of organism-environment interactions ● The study of the more strictly biological attributes of the organisms — their individual life histories, their interactions with one another, and their integration into communities(群 落) Levels of ecological organization and examples of the kinds of questions asked by ecologists working at each level Individuals Physiological ecology Behavioral ecology Population • Study the factors influencing population structure and process Adaptation Extinction Distribution abundance population growth interaction • Predation • Parasitism • competition How do Ecology and Paleoecology differ Can we observe the actual ecosystem? Ecological study = yes, Paleoecological study = no Can we select the organism and / or community for study? Ecological study = yes, Paleoecological study = only sometimes Are our observations based upon repeatable experiments? Ecological study = yes, Paleoecological study = no Do our studies operate within a defined timescale and space? Ecological study = yes, Paleoecological study = no Evolution Biogeography Physical environment Biota Diagenesis Rock facies Ecosystem Causal influence Palaeoecosystem Causal relationships in biology and geology pertinent to ecology and paleoecology What are some problems inherent in paleoecology reconstruction? One of the major limitations of the study of paleoecology: Not all species are preserved as fossils The Biocoenosis (life assemblage) does not equal the Thanatocoenosis (death assemblage) (1) What we don't see may be as important as what we do: Not every creature was fossilized (2)Fossil beds are composites of fossils (3)The older the material, the more likely it was modified, or destroyed by geological events or biological intrusions (4)At best you are sampling just a portion of what existed A lot of assumptions must be made given the paucity( 缺 乏 ) of data available in order for paleoecologists to generate ecosystems of the past. They must assume: The ecological relationships we use today to describe system dynamics are those that held in the past Trophic dynamics energy flow transfers competition & predation parasitism and so on where common controlling determinants of ecosystem functioning We have no real reason to doubt this at this time That animal, plants & microbes had more or less the same environmental habitats and to an extent niches as those today - fish live in water etc Since all that is left generally is the morphology of bones, pollen, wood etc. that these morphological adaptations to environment fit the pattern existent today what is the importance of paleoecological study for ecologists? It tells us how we got to where we are today It shows us the range of natural variation of communities and climates It gives us hints of where we might be headed in the future, especially during a period of potentially rapidly changing climate • 1. What is Paleoecology? • 2. The data base in paleoecology • 3. The operational base in paleoecology • 4. The nature of the fossil record Paleoenvironmental reconstruction depends on three ingredients: a well-established stratigraphic framework good taxonomy a comprehensive ecologic background ● The stratigraphic setting provides the spatial and temporal relationships(时空关系) for the comparison of fossils within geologic history ● The basic data of paleoecology are the fossils, adequately identified and correctly positioned within the stratigraphic framework The necessary ecology(常规生态学) consists of an understanding of the ways in which living organisms function within their ecosystem; how their morphology and physiology is adaptive to their conditions of life; the ways in which they may interact with one another; and the ways in which they may modify their life history to fit the environment l At one end of the spectrum general ecologic "laws" developed inductively from the living world are applied deductively to the fossil record l At the other end of the spectrum the present day significance of a particular species or morphologic feature is applied to the same species or biotic characteristic in the fossil record • 1. What is Paleoecology? • 2. The data base in paleoecology • 3. The operational base in paleoecology • 4. The nature of the fossil record The operational base in paleoecology uniformitarianism(均变论) analogy(同功原理) simplicity(简化法) or Parsimony Uniformitarianism Hutton (1726-1797) Lyell (1797-1875) • James Hutton, Scottish farmer, physician, and geologist; father of geology; published “The Theory of the Earth” (1785) • Charles Lyell, English geologist, published “Principles of Geology” (1830-1833) • “The past history of our globe must be explained by what can be seen to be happening now” • “The present is the key to the past” (Sir Archibald Geike, 18351924) • Giving enough time, modern Earth processes were capable of having produced the record of the past • Implies deep time Uniformitarianism can be classified as either substantive or methodological (Gould, 1965). Substantive uniformitarianism (实质均 变论) implies that the materials, conditions, and rates of processes during earth history have remained constant Methodological uniformitarianism (方 法均变论) implies that the laws of nature (such as gravity, the properties of fluid flow, and thermodynamics) have been constant in their operation through geologic time Four Meanings of Uniformitarianism • Methodological – Uniformity of Law: Foundation of historical science – Uniformity of Process: Actualism(现实主义) • Substantive – Uniformity of Rate and magnitude: Gradualism (Things do change, but at constant rate) – Uniformity of Condition: nondirectionism (Things do not change; or the Earth system has been maintaining the same equilibrium state) Catastrophism Cuvier (1769-1832) Brongniart (1770-1847) • Baron Georges Leopold Cuvier (1769-1832) and Alexander Brongniart (1770-1847) • Studied fossils in the Paris Basin • Dramatic changes in successive fossil assemblages • Believed that these changes were caused by total extinction resulted from catastrophes akin to the Noachian Deluge, followed by successive creations of new species • We now know that these abrupt changes are largely due to unconformities or missing record • Catastrophism has not been totally abandoned; it is particularly instructive in later studies on mass extinctions Analogy (or actuopaleontology (实证古生物学)) involves the application of modern organismic features to ancient organisms. This principle may be applied to : individuals (with regard to form and function) community structure (species diversity, organizational and trophic structure(营养结构) and population dynamics (response to timeindependent environmental factors), and is inferred to represent response to timeindependent environmental forces Whenever we find, in two forms of life that are unrelated to each other, a similarity of form or of behavior patterns which relates to more than a few minor details, we assume it to be caused by parallel adaptation to the same life-preserving function 章鱼 人类 Simplicity or Parsimony Principle of simplicity: everything else being equal, the best explanation is the simplest one Simplicity in this sense is that the most probable explanation is generally the one with the fewest steps from cause through intermediate causes and effects to the final result Ockham's Razor This simplifying procedure should be valid in paleoecology because it is exactly that used in ecology, and in science in general It saves us from the despair of attempting to derive from the limited paleontologic data an explanation incorporating the myriad of environmental parameters • 1. What is Paleoecology? • 2. The data base in paleoecology • 3. The operational base in paleoecology • 4. The nature of the fossil record A fossil assemblage may be only a small and biased representation of the original community Destruction by various processes after death of the organism, a potential fossil may not be preserved Taphonomy (1) It helps in understanding the relationship of the fossil assemblage to the original community and thus allows to some extent the reconstruction of the community (2) Recognition of taphonomic processes that have formed the fossil assemblage provides insight into the depositional and postdepositional environment Subsidiary topics within taphonomy are necrolysis (尸积学), which deals with the decomposition of the organism upon death, biostratinomy(化石产生学), which deals with the sedimentational history of the fossil, and fossil diagenesis, which deals with chemical and mechanical alteration of the fossil between the time of its burial and collection During each of these stages of the post-mortem history, mechanical, chemical, and biological processes are reshaping the original community Two opposing views on processes that form from the original community the assemblage of fossils One is that a fossil assemblage accumulates slowly through the yearby-year preservation of some fraction of the community Thus the assemblage represents a time-averaged sampling of a sequence of communities over a period of years and of perhaps a considerable range of environments (Fürsich, 1978) The opposing view is that preservation is in general so poor, the fossil record is much more likely the result of occasional chance preservation of an individual community Thus an assemblage may be a fairly reasonable representation of the community existing during a short interval rather than the accumulation of meager sampling during a longer time interval • 1. What is Paleoecology? • 2. The data base in paleoecology • 3. The operational base in paleoecology • 4. The nature of the fossil record Text books and references: 陈源仁,1992. 生态地层学原理. 北京:地质出版社 孙儒泳,李 博等, 1993. 普通生态学.北京:高等教育出版社. 杨式溥, 1983. 古生态学及遗迹化石学. 武汉地质学院古生物教 研室. 殷鸿福等,1988. 中国古生物地理学.武汉:中国地质大学出版社 Boucot, A.J., 1981, Principles of Academic Press. Benthic Marine paleocology, Dodd, J.R. and Stanton, R.J., 1981, Paleoecology, Concepts and Applications. John Wiley and Sons. Allmon W. D., Bottjer D. J.,2001. Evolutionary paleoecologyThe ecological context of macroevolutionary change.New York: Columbia University Press.