ECOLOGY - INTRODUCTION

1. ECOLOGY - INTRODUCTION DEFINITION The scientific study of the interaction of organisms with their environment Read: Krebs textbook “Ecology” 5th ed. Chapters 1 and 2

2. ECOLOGY AND EVOLUTION • Ecology is related to other subjects GENETICS EVOLUTION ECOLOGY PHYSIOLOGY BEHAVIOUR

3. ECOLOGY - INTRODUCTION 1. INTERACTION All processes in the world are linked - changes in one component affect others

4. ECOLOGY - INTRODUCTION 2. ORGANISMS AND ENVIRONMENT a) Biotic – the living component – food, competitors, predators b) Abiotic – the physical & chemical component – physical structure, climate e.g. temperature, humidity, pH

5. ECOLOGY - INTRODUCTION 3. SCIENTIFIC STUDY The scientific method is the systematic attempt to disprove erected postulates or hypotheses Hypothesis Proof and disproof Probability and statistics

6. EVOLUTION AND NATURAL SELECTION Evolution means change – in this context change in a species. First proposed by ERASMUS DARWIN and LAMARCK early1800s Natural Selection – the mechanism of evolution first proposed by CHARLES DARWIN & A.R. WALLACE in 1858 at Royal Society lecture DARWIN – ‘On the origin of species’ 1859 THOMAS MALTHUS – late 1790s – on population increase and starvation and disease.

7. Lamarck proposed that by continued use of a body component it increased in size and efficiency, e.g. stretching for food by giraffe caused it to lengthen its neck, and pass this on to its offspring.

8. Charles Darwin 1850s

9. DARWIN'S THEORY Fact 1. Any species can increase its population geometrically. Fact 2. Population size remains constant over time. Fact 3. All organisms can be seen to be variable. Postulate 1.(from facts 1 & 2): There is competition amongst progeny for survival. Postulate 2. (from Postulate 1 & Fact 3): Since there is competition, some variants will be better adapted, compete more successfully and reproduce better. These variants will comprise the next generation. This is the process of natural selection.

10. Galapagos Islands -tortoises differ in size and shape on each island

11. Darwin’s example of human produced artificial selection Artificially Selected types Wild rock dove

12. NATURAL SELECTION & EVOLUTION 1. Some individuals will produce more offspring that survive and reach maturity than others. 2. These individuals are those best able to survive and reproduce in a given environment. They are better adapted. 3. The genes of such individuals will predominate in the following generations. 4. This is natural selection: It is the process that allows some types to survive and reproduce better than others. 5. When the environment changes the original types are now less well adapted, and variant types, by chance, may be better adapted. If so, they will spread and the species changes. This is evolution. 6. Therefore in a changing environment Adaptation leads to evolution.