 Show Laboratory 3 Write-Up: Introduction to Evolution II Due to the length of this lab, there are no post lab questions. Each question is worth 0.5 points. II. Stickleback Evolution Virtual Lab 1. Define “model organism.” A model organism is a nonhuman species that is vigorously studied to further an understanding of a biological phenomena. 2. Why is the threespine stickleback a model organism for studies in evolution? (List at least two reasons.) It is a model organism for studies in evolution because they are easy to study due to their short generation time and their small demeanor. 3. How do spines protect ocean stickleback fish? Spines protect ocean Stickleback fish sticking out its pelvic spines and dorsal spines so predators have a hard time swallowing it. 4. Describe where its spines are located. Three spines are on its dorsal side, and two spines are on its ventral side. The spines on its ventral also help protect it from its pelvis. 5. The loss of stickleback pelvic spines is similar to the loss of which body parts in some other four- legged vertebrates? It is similar to the loss of hind limbs. 6. Name two other vertebrate animals whose evolutionary histories included the loss of hind limbs. Two other vertebrate animals are manatees, snakes, and whales. 7. In addition to the spines, what is another component of the “armor” of a stickleback fish? Another component of the armor is the row of plates on both sides of its body. 8. Explain how the stickleback armor protects the fish from some predators. The spines stick out in almost a 90-degree angle making it really hard for predators to swallow them. The plates stick out a little too and makes it extra hard for the predators to swallow it. 9. How did ancestral populations of ocean-dwelling fish come to live in freshwater lakes? Why is the three spine stickleback a model organism for studies in evolution?Another reason that stickleback are useful model organisms for studies in evolution is that there are many stickleback fossils, so researchers can compare living populations to their ancestors. several vertebrate lineages, including manatees, snakes, and whales.
What is the purpose of the spines of sticklebacks?The many stickleback populations underwent disparate and parallel evolutionary changes, among them partial or complete loss of their pelvic spines. These spines are thought to protect the fish from being devoured by predators.
How is the stickleback fish an example of evolution?Dorsal spine reduction in threespine sticklebacks (Gasterosteus aculeatus) is a classic example of recurrent skeletal evolution in nature. Sticklebacks in marine environments typically have long spines that form part of their skeletal armor. Many derived freshwater populations have evolved shorter spines.
Why are pelvic spines beneficial for some sticklebacks and a disadvantage for others?Pelvic spines provide stickleback fish with a defense against such predators; however, pelvic spines appear to be a disadvantage in habitats without large-mouthed predatory fish and/or habitats with insects that can grab the spines, so that they can eat the fish.
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Why is the three spine stickleback a model organism for studies in evolution list at least two reasons?
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