West Valley College REVIEW - Unit 7_ Natural Selection BIO 10

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TOPIC 7.2 Natural Selection Unit 7: Natural Selection ENDURING UNDERSTANDING EVO-1 Evolution is characterized by a change in the genetic makeup of a population over time and is supported by mu... ltiple lines of evidence. LEARNING OBJECTIVE EVO-1.E Describe the importance of phenotypic variation in a population. ESSENTIAL KNOWLEDGE EVO-1.E.1 Natural selection acts on phenotypic variations in populations. EVO-1.E.2 Environments change and apply selective pressures to populations. EVO-1.E.3 Some phenotypic variations significantly increase or decrease fitness of the organism in particular environments. ILLUSTRATIVE EXAMPLES § Flowering time in relation to global climate change § Peppered moth § Sickle cell anemia § Plant species A is stimulated to produce flowers in response to warming weather in the Spring. Plant species B is stimulated to produce flowers when hours of daylight become longer in the Spring. Which species would be most affected by the selective mechanism of Climate Change? Explain your reasoning. Plant species A is stimulated to produce flowers in response to warming weather in the Spring whereas plant species B is stimulated to produce flowers when hours of daylight become longer in the Spring. Climate fluctuations occur a lot during the Spring season. The weather changes and swings between warm and chilling temperatures. Bright sunshine in a week can be followed by a colder environment many times. In fact, weather can also be altered immensely even on the same day. Whatever be the weather conditions during the spring season, one thing is for sure, that is the daylight, Earth rotates on its axis in 24 hours, so we have a day of 12 hours followed by a night of 12 hours. Even if the weather is chilling, daylight will occur, just its intensity will be weak. So, climate change will affect plant species A more compared to plant species B, because plant species A needs warmer temperatures during the spring season for blooming, but it's not necessary that it's always good warmer weather during this season. As far as species B is concerned, daylight will always be there whether the temperature is cold or warm in seasons, so species B will have less effect than species B. A farmer uses DDT to kill insects in his field. The first year nearly all of the insects were killed. By the fourth year, however, nearly all of the insects survived the DDT treatment. Explain the process of natural selection in this population of insects. Include these words - mutation, phenotype, variation, resistance, adaptation, and differential survival. Natural selection is the process in nature by which organisms better adapted to their environment tend to survive and reproduce more than those less adapted to their environment. simple words- This variation means that some individuals have traits better suited to the environment than others. For example, treefrogs are sometimes eaten by [Show More]

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