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Knocked Out By Trout: The Relationship Between Nonnative Trout and Pacific Tree Frogs

This article is from Issue Invasive Species - Vol. 8 No. 1.

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The scientists were interested in discovering whether the Pacific tree frog population might also be affected by the presence of nonnative trout, similar to the way these trout had affected the mountain yellow-legged frog population. The scientists wanted to compare the populations of Pacific tree frogs with the populations of nonnative trout in JJohn Muir Wilderness (JMW) and Kings Canyon National Park (KCNP).

Welcome to the Invasive Species edition

Note to Educators

Invasive Species Lesson Plan

Student Notes Page

Reflection Section Answer Guide

Education Standards Correlations


Meet the scientists that contributed to this article:

"Science Topics" covered in this article:
  • Life Science
  • People and Science

"Environmental Topics" covered in this article:
  • Wildlife and Endangered Species (Educators)

Regions covered in this article:
  • Alaska
  • Forest Products Lab
  • Intermountain
  • International Institute of Tropical Forestry
  • Northern
  • Pacific Northwest
  • Pacific Southwest
  • Rocky Mountain
  • Southern
  • Southwestern

"Thinking About Science Themes" covered in this article:
Although all biological scientists collect data, they know the differences between a study done in a laboratory and one done in the natural world. One difference has to do with the concept of control. When scientists want to discover the effect something has had on something else, they try to control the things that can vary, except for the things that they want to observe. This is much easier to do in a laboratory than in the natural world. In a laboratory, for example, if a scientist wants to discover the best temperature for seed germination, she can control the amount of heat reaching different seeds and compare their growth. In the natural world, this kind of control is difficult to create. In this study, the scientists found an unusual situation in the natural world that enabled them to study the effect of nonnative trout on a tree frog population. In this study, you will learn how past and current natural resource management action controlled one of the most important variables, providing an opportunity for the scientists to study the relationship between nonnative trout and tree frogs.
Specific "Thinking About Science" Themes:
  • The Scientific Process

"Thinking About Environmental Themes" covered in this article:
In a native ecosystem, the living components have adapted together over time. This usually results in a stable ecosystem, meaning that within certain limits of fluctuation and possible continuous but slow change over time, the components remain about the same. This stability is threatened when a natural or human-created disruption occurs within the ecosystem. A natural disruption is something such as a hurricane, flood, or volcano. Human-created disturbances include things such as cutting down all the trees, mining, and building roads and buildings. Another way that humans have created disturbances within stable ecosystems is by introducing nonnative species into these native ecosystems. When a nonnative species is introduced into a stable native ecosystem, the relationships that have defined that ecosystem change. Often, the nonnative species has a negative effect on the native ecosystem. In this study, the scientists wanted to know how the population of Pacific tree frogs was affected by the introduction of nonnative trout into lakes that had historically had no fish living in them.
Specific "Thinking About the Environment" Themes:
  • Cycles

NSE Standards covered in this article:
  • Abilities necessary to do scientific inquiry (A)
  • Diversity and adaptations of organisms (C)
  • History of science (G)
  • Nature of science (G)
  • Populations and ecosystems (C)
  • Regulation and behavior (C)
  • Risks and benefits (F)
  • Science and technology in society (F)
  • Science as a human endeavor (G)
  • Understandings about scientific inquiry (A)