Transcript Document
SC 225 Environmental Science Unit 2: Populations, Communities and Species Interaction Bronwyn Scott [email protected] AIM: [email protected] Welcome to Seminar Two • Please turn your speakers on. This seminar contains audio. • While we are waiting to get started this evening, please take this opportunity to chat. • If you encounter any technical issues accessing a KHE Seminar, please call KU ACE Help 1-866522-7747, option 2, then option 1. You may also email KU ACE Help at [email protected]. Ecological Society of America (ESA) meeting in the Yucatan, Mexico (2006) Seminar Agenda 1. Unit 2 Discussions: Learned social behaviors and genetic testing 2. Unit 2 Project: Philosophies of Conservation 3. Seminar: Evolution and Human Population 4. Q & A Two Meanings of Evolution Evolution as a process – change in the features of individuals in a population over generations Examples: • Head lice resistant to pesticide • Cancer cells resistance to chemotherapy • Plants resistant to Round Up Microevolution – changes that occur in characteristics of a population The Theory of Evolution All organisms present on Earth today are descendants of a single common ancestor, and all organisms represent the product of millions of years of microevolution Scientific Theory • “Theory” is used commonly to mean best guess • This is not how it is used in science • Scientific theory is a body of scientifically acceptable general principles that help explain how the world works • The Theory of Evolution is so well supported by evidence that it is considered a fact by biologists • Evolution is the foundation of modern biology Other theories which are considered scientific laws/facts in science… • Theory of gravity – explains motion of planets • Atomic theory – explains relationships between chemical elements & molecules • Theory of relativity – relationship between mass & energy “Nothing in biology makes sense except in the light of evolution”, Theodosius Dobzhansky Evolution: Natural Selection and Adaptation • Adaptation – physical changes that allow organisms to survive in a given environment • Natural Selection – The mechanism for evolutionary change in which environmental pressures cause certain genetic combinations in a population to become more abundant • Selective Pressure – Limited resources or adverse environmental conditions that tend to favor certain adaptations in a population Question #1 • What evidence exists in living species that would lend support for the theory of evolution? Question #2 • How do the forces of natural selection work to favor species changes? A Living System • Species – organisms that can breed • Population – members of a species that live together • Community – All populations living and interacting together • Ecosystem – a biological community and its physical environment Species Interactions • Competition: • Intraspecific: within one species (say a population) • Interspecific: between two different species • Symbiosis – the intimate living together of two or more species • Mutualism: both (or all) benefit • Commensalism: one species benefits, and the other one is indifferent • Parasitism: one benefits and the other is harmed Question #3 • How is mutualism different from competition? What advantage does it have? Question #4a • What is ecological succession? Primary Succession on Land Question #4b • How do recent fires affect it ecological succession? Question #5 • What was the difference between the Malthusian and Marx's view of the solution to human population growth? Questions? Image credit: Microsoft Clip Art Malthusian Checks on Population • Reverend Thomas Malthus (1766 – 1834) – British • Human populations growing at exponential or compound rate • Food production stable or grows slowly • Human populations will collapse into starvation, crime & misery • “Positive checks” like disease and famine • “Preventative checks” like preventing too many births More Malthus • Although he was a Reverend & promoted late marriage & celibacy, he had several illegitimate children & had no faith in moral restraint • He thought people were “too lazy & immoral” to regulate births voluntarily • He opposed efforts to feed or assist the poor, as that would just increase their fertility • A little blunt, but was he wrong? • If this were mice instead of humans we were talking about…wouldn’t feeding them increase their numbers? Karl Marx (1818-1883) - Germanic • Vehement critic of Malthus who called him a “shameless sycophant of the ruling classes” • Sycophant = a person who tries to please someone in order to gain a personal advantage • Population growth was a symptom rather than a cause • Slow population growth by alleviating crime, disease, starvation, misery and environmental degradation through social justice Classic Population Theories • What causes populations to rise and what does that have to do with environmental science? • Relationships between resources, population growth and poverty are not clearcut and may be subject to political interpretations. • For instance, Malthus argued (model a) that poverty is a result of overpopulation. • Karl Marx (model b) argued that oppression and exploitation are the causes of poverty, which then results in high population growth.