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Across 1. a region inhabited by a characteristic set of taxa bounded by barriers that prevent emigration and immigration 6. type of biome occurring where the average temperature and rainfall are high and relatively constant throughout the year 10. species that have large effect on its community or ecosystems 12. number of feeding levels away from the original source of energy in the ecosystem 15. given sufficient time and similar climates, species similar in shape and form will tend to occur 20. system of management of natural resources and the environment based on fundamental ecosystem concepts 21. also referred to as realms characterized by the presence of dominant families of animals 23. type of biome where the tree growth is hindered by low temperatures and short growing seasons 25. practical delineation of the boundary of an ecosystem 26. species occupying the base of the food chain 28. process in which organisms diversify rapidly from an ancestral species into a multitude of new forms 29. occurred 600-500 million years ago characterized by the emergence of earliest multicellular organisms 30. term for the first animals on land

Down 2. according to this theory small islands tend to have fewer habitat types and islands tend to maintain consistent number of species over time 3. organisms that produce sugar from carbon dioxide and water 4. according to this concept, the accumulation of changes may lead to reproductive isolation resulting to new species 5. occurred 420-360 million years ago characterized by the emergence of first terrestrial animals 7. English naturalist and biologist who explained that biodiversity was brought about by biological evolution 8. variety of life forms found in an area 9. a set of interacting species found in the same place and functioning together to maintain life 11. small number of individual species are isolated from larger population resulting in less genetic variation than original population 13. cycling of chemical elements and flow of energy 14. the different types of habitats in a given unit area 16. feeding relationship found in aquatic and marine ecosystems 17. vegetation type occurring in climates warmer than boreal forests 18. made up of two components, living and non-living 19. type of biome which are found in the driest regions where rainfall is less than 50 cm/year 22. boreal forests of the cold climates of high latitudes and high altitudes regions 24. changing of the structure of the gene resulting to a variant form that may be transmitted to subsequent generations 27. large naturally occurring community of flora and fauna occupying a major habitat characterized by similar physical environment