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Ch. 27 - Diversification of Eukaryotes
Chapter 26, Problem 8

The text claims that the evolutionary history of protists can be understood as a series of morphological innovations that established seven distinct lineages, each of which subsequently diversified based on innovative ways of feeding, moving, and reproducing. Explain how the Alveolata support this claim.

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Step 1: Understand the question. The question is asking you to explain how the Alveolata, a group of protists, supports the claim that the evolutionary history of protists can be understood as a series of morphological innovations that established distinct lineages, each of which subsequently diversified based on innovative ways of feeding, moving, and reproducing.
Step 2: Research the Alveolata. Alveolata is a major group of protists which includes organisms like dinoflagellates, apicomplexans, and ciliates. They are characterized by the presence of alveoli, or small vesicles, beneath their cell membranes. These alveoli are thought to provide support to the cell surface.
Step 3: Identify the morphological innovations in Alveolata. The presence of alveoli is a morphological innovation that distinguishes Alveolata from other protists. Additionally, different groups within the Alveolata have other unique features. For example, dinoflagellates have two flagella for movement, apicomplexans have a unique organelle called an apicoplast, and ciliates have cilia for movement.
Step 4: Explain how these innovations led to diversification. The unique features of each group within the Alveolata allowed them to adapt to different environments and lifestyles. For example, the flagella of dinoflagellates allow them to move in water, the apicoplast of apicomplexans is thought to be involved in processes like lipid synthesis, and the cilia of ciliates allow them to move and feed.
Step 5: Summarize your findings. The Alveolata support the claim that the evolutionary history of protists can be understood as a series of morphological innovations that established distinct lineages, each of which subsequently diversified based on innovative ways of feeding, moving, and reproducing. The presence of alveoli and other unique features in different groups within the Alveolata allowed them to adapt to different environments and lifestyles, leading to their diversification.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Morphological Innovations

Morphological innovations refer to significant changes in the structure and form of organisms that can lead to the emergence of new traits or lineages. In the context of protists, these innovations may include adaptations in cell structure, such as the development of specialized organelles or unique shapes, which enable them to exploit different ecological niches and enhance survival.
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Alveolata

Alveolata is a major group of protists characterized by the presence of alveoli, which are membrane-bound sacs located beneath the plasma membrane. This group includes diverse organisms such as ciliates, dinoflagellates, and apicomplexans, each exhibiting unique feeding, movement, and reproductive strategies that illustrate the evolutionary adaptations stemming from their morphological innovations.
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Diversity in Feeding, Movement, and Reproduction

The diversity in feeding, movement, and reproduction among protists, particularly within the Alveolata, highlights how morphological innovations can lead to varied ecological strategies. For instance, dinoflagellates possess unique flagella for movement and can photosynthesize, while apicomplexans have evolved complex life cycles for reproduction, showcasing how these adaptations contribute to their evolutionary success and ecological roles.
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Related Practice
Textbook Question

The most important primary producers in marine ecosystems are               .

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Textbook Question

Evaluate the following statements regarding motility in protists. Select True or False for each statement. T/F Amoeboid motion is common in species with cell walls. T/F Some protists use flagella to swim. T/F Some protists use cilia to swim, which are shorter and more numerous than flagella. T/F Amoeboid motion requires ATP and interactions between the proteins actin and myosin.

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Textbook Question

How can dinoflagellates be harmful to humans? a. They are transmitted by mosquitoes and cause malaria. b. They produce toxins that can be absorbed by clams and other shellfish which, when eaten by people, can lead to paralytic shellfish poisoning. c. They cause amoebic dysentery which leads to severe diarrhea and dehydration. d. They are transmitted by tsetse flies and cause 'sleeping sickness.'

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Textbook Question

Consider the following: Plasmodium has an unusual organelle called an apicoplast. Recent research has shown that apicoplasts are derived from chloroplasts via secondary endosymbiosis and have a large number of genes related to chloroplast DNA. Glyphosate is one of the most widely used herbicides. It works by poisoning an enzyme located in chloroplasts. Biologists are testing the hypothesis that glyphosate could be used as an antimalarial drug in humans. How are these observations connected?

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Textbook Question

Suppose a friend says that we don't need to worry about the rising temperatures associated with global climate change. She claims that increased temperatures will make planktonic algae grow faster and that carbon dioxide (CO2) will be removed from the atmosphere faster. According to her, this carbon will be buried at the bottom of the ocean in calcium carbonate shells. As a result, the amount of carbon dioxide in the atmosphere will decrease and global warming will decline. Comment.

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Textbook Question

When placed at the perimeter of a maze with food in the center, the plasmodial slime mold Physarum polycephalum explores the maze, retracts branches from dead-end corridors, and then grows exclusively along the shortest path possible to the food. How does Physarum do this? One theory is that it leaves behind slime deposits—an externalized 'memory' that 'reminds' it not to retry dead ends. Which of the following best describes movement in Physarum? a. Cilia propel the slime mold. b. Flagella propel the slime mold. c. The slime mold moves by amoeboid motion. d. The slime mold moves by gliding motility.

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