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Process of Natural Selection Foldable Natural Selection = NS GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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NS – individuals better adapted to their environment survive and reproduce more successfully than less well-adapted organisms do. GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Overproduction egg sac GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Overproduction: organisms in a populationproduce more offspring than their environment can support. Many die through predation or starvation GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Example: Tarantula’s egg sac holds 500 to 1,000 eggs. Some eggs survive and develop into adult spiders and some die. GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Photography of Egg sack - Poecilotheria pederseni
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The moulting process
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Genetic Variation Within A Population GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Variation: Differences in a population of organisms of the same species. Variations/Genetic Adaptations - passed to offspring from parents through genes/alleles. GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Example: Every individual has its own combination of traits. Each tarantula is similar, but not identical, to its parents. GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Struggle to Survive (adaptation) GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Newly inherited traits help organisms survive and reproduce in their environment. Some variations are favorable and help organisms compete to survive and reproduce. GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Example: Some tarantulas have traits that make it more likely they will survive. better able to fight off predators GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Adult female Brachypelma smithi, showing a bald patch after kicking hairs off of her abdomen.
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Successful Reproduction (natural selection) GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Over time, offspring with helpful variations increase and become a larger percentage of the population. The organisms with favorable variations become plentiful. The ones without favorable variations become rare or extinct. GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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Example: Tarantulas best adapted to their environment are likely to survive and reproduce. Offspring may inherit traits that help them survive. GLE 0807.5.3 - GLE 0807.5.4 - SPI 0807.5.2 - SPI 0807.5.3
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