ADAPTATION, FITNESS, AND REPRODUCTIVE SUCCESS In biological systems, adaptation has three different meanings. First, it is the process that helps an organism fit into their environment so that it is evolutionarily fit. Second, it is a state that is reached by a specific population as part of the fitness process. Third, it is any phenotypic trait that is maintained because it has evolved through natural selection. Darwin believed that adaptation was a big part of natural selection. Adaptation is directly related to the biological fitness of an organism. Gene frequencies in a population help to determine who adapts and who does not adapt. Sometimes, adaptation happens because more than one species coevolves in order to become entwined with one another in the evolutionary process. Teleology refers to the structure and purpose of the different body features of an organism, which contributes to their adaptation. While adaptation relates to teleology, it is not the same thing. Adaptation is an actual process that happens because of the form and function of a body part. There are many parts of a plant or animal that can be called adaptations, which are things that increase the fitness of the organism in its environment. The diversity of organisms in the environment is dependent on two different things: speciation and adaptation. Adaptation does not lead to reproductive isolation but speciation does. Adaptation is not simply having the ideal phenotype for a given environment. For example, an organism must remain viable at all of its different stages of development and must be viable as evolution progresses. Each genetic change and each phenotypic change in the different generations must be small because environments and the relationship between the organism and the environment are very complex. Even so, some adaptations have been very big, such as when eukaryotes were first developed in the evolutionary process by engulfing certain prokaryotes that led to the development of chloroplasts and mitochondria. Adaptations help an organism survive in its particular niche. Adaptations can be physiological, structural, or behavioral. Structural adaptations can be seen, while physiological adaptations cannot be seen but are determined through biochemistry or microbiology. Behavioral adaptations are inherited behaviors, like instincts or the capacity to learn. Mating patterns, the ability to find food, and vocalizations are behavioral adaptations, while making slime, phototropism, and the making of venom are physiological adaptations. Other physiological adaptations involve the ability to regulate temperature and things that affect growth and development.
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