7. What is a species? With so many different types of species, how can we make sure we don ’t get them confused? What makes one species different to another species? What factors can affect survival?
8. Recall : a species is a particular type of organism. Recall : members within a population of a species can interbreed and produce fertile offspring. Recall : each species is given a scientific name (they are classified).
9. Each individual has unique genes (including mutations) controlling its structure and function. Each individual is suited (adapted) to its environment. How have these organisms adapted to their environment?
10. Members of the same or different species compete for resources, such as light, food etc. Those that are most ‘fit’ will survive. Others die. Can you explain this graph?
11.
12. Natural Selection happens when those better adapted organisms have an advantage and survive to reproduce . The others die. There are four points to remember. 1 . More offspring produced than can survive so they compete (struggle for existence).
13. 2. Variation exists within and between species. Those with the most suited adaptations will outcompete the others. They will survive and the others will die. This is ‘survival of the fittest’
19. Isolation also leads to different species being produced that are unable to interbreed and produce fertile offspring. Physical isolation: - geographic isolation can prevent interbreeding, - each species undergo mutations and change slowly, - however, they do not share genes, - species eventually become different and cannot interbreed even if given the chance.
22. 1. Plate activity resulted in separation of gene pools by forming physical barriers. This can trigger speciation. Plate Tectonics
23. 2. Plate activity may result in ‘land bridges’, e.g. more recently between North and South America. Land bridges allow species to invade new areas. E.g. bears have moved from North to South America. Plate Tectonics
24. 3. Locations of continents influence climate. This generates new and diverse habitats, promoting biodiversity. E.g. Antarctica was a forest before moving south, forcing species to adapt. Plate Tectonics
25. Succession Imagine there is a new volcanic island in the middle of the ocean with no life on it. Describe how one day, in millions of years, it will be a forest.
26. The development of a community in a predictable sequence from a pioneer species to a climax community that remains in equilibrium. Succession
27. A pioneer species is an opportunistic coloniser of vacant or vacated habitats. They have high reproductive and dispersal rates. A climax community is a persistent array of species in a stable community. Succession
28. Diversity changes through succession. A complex community has a variety of nutrient and energy pathways. It is stable. Greater habitat diversity leads to greater diversity in species. Succession
30. An ecosystem ’s capacity to survive change may depend on diversity (number and proportions of species), resilience (ability to recover) and inertia (ability to resist change). Maintaining biodiversity
31. Maintaining biodiversity The capacity of a tropical rainforest to survive a bush fire: - diversity: high diversity, - inertia: high resistance to alteration, - resilience: low - recovery takes a long time, Catastrophic disturbances are greatest threat. Capacity of a tropical rainforest to survive a fire: - diversity (high or low)? - inertia (high or low)? - resilience (high or low)?
32. Maintaining biodiversity The capacity of grasslands to survive a bush fire: - diversity: low diversity, - inertia: low resistance to alteration, - resilience: high - recovery takes a short time, Burn easily, but recover quickly. Capacity of a grasslands to survive a fire: - diversity (high or low)? - inertia (high or low)? - resilience (high or low)?
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