Natural Selection Lecture Notes

Amoeba Sisters Video Recap: Natural Selection 1. Populations can have variety, despite being made up of the same species. If a population has different expressed traits, this can be due to different inherited alleles. The frogs below are the same species, but they have different shades of green based on their inherited alleles. In a particular environment, lighter green frogs are easier to see by predators. Explain how natural selection could lead to a change in allele frequency. In the case of the frogs, natural selection could lead to 2. Natural selection is an example of a mechanism of evolution. Does this mechanism produce a change in individuals or populations? Explain! Natural selection is a mechanism of evolution that a change in allele frequency because the lighter green produces a change in populations over time. It works by frogs, which are easier for predators to see, might be favoring individuals with traits that help them survive more likely to be caught and eaten. This means that and reproduce. So, it's all about the population, not just fewer frogs with the allele for lighter green color would individuals. survive and reproduce, while the frogs with darker green color would have a better chance of survival. Over time, this could result in a higher frequency of the allele for darker green color in the population. _ _ 3. A major point of understanding natural selection is that not all organisms in a population gets to reproduce. Consider the term fitness as used in biology. How does does this term relate to natural selection? fitness refers to an organism's ability to survive and reproduce in its environment. The more fit an organism is, the more likely it is to pass on its traits to the next generation. So, in the context of natural selection, organisms with higher fitness have a greater chance of passing on their beneficial traits, while those with lower fitness may not reproduce as successfully 4. Based on your answer above, do organisms with higher fitness mean that they have survived to an advanced age? Why or why not? No, fitness doesn't necessarily mean that organisms have survived to an advanced age. Fitness is determined by an organism's ability to survive and reproduce, not by its age. An organism could have high fitness if it successfully reproduces at a young age and passes on its beneficial traits to the next generation. So, it's more about reproductive success than age when it comes to fitness. 5. Does fitness(as used in biology) and survival have the same meaning? Why or why not? No, fitness and survival do not have the same meaning in biology. While survival is a part of fitness, fitness encompasses more than just survival. Fitness refers to an organism's overall ability to survive, reproduce, and pass on its genes to the next generation. It takes into account factors like reproductive success, adaptation to the environment, and genetic contribution. So, survival is just one aspect of fitness. 6. If an organism has high biological fitness in one environment, does that mean that it would also have high biological fitness in another environment? Why or why not? No, having high biological fitness in one environment does not necessarily mean that an organism would have high biological fitness in another environment. The fitness of an organism is dependent on its ability to adapt and thrive in a specific environment. Different environments present different challenges and selective pressures. Traits that may be advantageous in one environment may not be beneficial or may even be detrimental in another. So, an organism's fitness is context-dependent and can vary across different environments 7. Two students are discussing natural selection in bacteria and how it can relate to antibiotic resistance in bacteria. Bernadette states that when antibiotics are used, bacteria can respond by developing traits to help them defeat the antibiotic, which then may increase their fitness. Dominique states that there is already a variety of traits among the bacteria. Bacteria that have traits that allow them to survive the antibiotic and reproduce may have higher fitness. Which individual's reasoning do you agree with more and why? Bernadette because it sounds more beneficial and has more background. 8. A major misconception about natural selection is that this mechanism “gives organisms what they want or need so they can adapt to an environment.” Explain why this is not correct. Natural selection is not a conscious process that gives organisms what they want or need. Instead, it's a result of random genetic variations within a population and the environmental pressures that select certain traits. Organisms don't actively choose or control their adaptations. Instead, those individuals with traits that are better suited to their environment are more likely to survive and reproduce, passing on those beneficial traits to future generations. So, it's more about survival of the fittest rather than organisms getting what they want or need. 9. Consider a major environmental change. If there are no organisms in a population that have traits that allow them to continue to survive to reproduce, what would likely happen to that population? If there are no organisms in a population that have traits allowing them to survive and reproduce in a major environmental change, then that population would likely face a decline or even extinction. Without the necessary adaptations, the organisms would struggle to cope with the new conditions, leading to a decrease in their numbers over time. It highlights the importance of genetic diversity and the ability to adapt to changing environments for the longterm survival of a population.