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Across 4. Competition between individuals of the same species. 8. The evolutionary process whereby species with similar requirements, living in the same habitat, evolve specialised traits that enable them to utilise the resources differently, creating separate niches. (2 words) 9. Birth rate in animals or production of seeds in plants. 10. The succession that begins on sites that have not previously had plants growing on it. 11. All the conditions necessary for an organism to survive and reproduce. 14. Species that exhibit the highest level of social organisation. 16. An interconnected set of all the food chains in an ecosystem.(2 words) 17. Group of different species that inhabit and interact in a particular area. 19. Organisms move into a population and stay. 20. The population density that the environment can support (2 words)

Down 1. No immigration or emigration takes place.(2 words) 2. Organisms leave a population and do not return. 3. When one of the two competing species is much more successful than the other. (2 words) 4. Competition between individuals of different species. 5. Made up of groups of different species of organisms that interact with each other and with the environment. 6. Increasing more and more rapidly. 7. Death rate. 10. Group of organisms of the same species that occupy the same area and can breed freely. 12. The succession begins in areas where disturbance removes some of the species but the soil remains. 13. An organism that hunts, kills and eats another species. 15. Official survey of the population. 18. This method involves counting the number of individuals in small measured areas.