SC 225 Environmental Science Unit 2: Populations, Communities and Species Interaction Bronwyn Scott AIM:

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 , option 2, then option 1. You may also KU ACE Help at 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 ( ) - 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.