Biodiversity Strand Overview
We propose that understanding the processes of evolution and the connected changes in diversity that occur in natural systems, is fundamental to environmental literacy, and is a critical component in environmentally responsible citizenship. Developing an understanding of the steps by which elementary, middle and high school students learn this content is essential in producing school-leavers who are able to apply their understanding of diversity and evolution to deciding on policies and personal actions that are consistent with their environmental values.
Diversity occurs at many levels in natural systems, from genetic diversity in populations, through diversity of species in communities, to diversity of habitats and ecosystems. Diversity at any level is not a constant, but rather it changes through a number of different processes. For example, genetic diversity in populations is increased by sexual reproduction and mutation, and is decreased by selection. Changes in the diversity in systems at different levels have direct effects on diversity in systems at other levels (e.g. habitat fragmentation can lead to smaller population sizes and reduced genetic diversity). Humans are increasingly altering the structure of natural populations, and are consequently having dramatic impacts on diversity at all levels, be that through altering the rate of births and deaths in populations; by removing selection pressures by introducing invasive species; or by altering ecosystems through agricultural or urban development. Since evolutionary theory is not merely science that can describe what has happened in the past, but also science that is predictive of what will happen in the future, it empowers us with a crucial understanding of the consequences of human alterations to natural systems.
The biodiversity learning progression has four levels of achievement, from informal force-dynamic accounts to scientific, model-based accounts.
Level 1: Anthropomorphic Narratives – Level 1 students have well developed anthropomorphic frames for explaining biodiversity-related phenomena: Their narratives include animals as principal actors that cooperate and compete in human ways, plants as scenery or food for animals, and humans as caregivers/care-takers. Nature films such as March of the Penguins are popular precisely because they embrace this perspective. They attribute changes in ecosystems to major catastrophic events, human intervention, or because organisms “need” to help each other or “want” to change. For example, one of our students explained that forest succession occurs because the trees “probably decided to change over time. Also they might’ve of not wanted to be a cottonwood tree and changed to a maple.” On the other hand, Level 1 students have poorly developed scientific knowledge and practice. They often have limited direct experiences in real ecosystems, and they tend to notice only phenomena taking place within a short time frame and limited spatial scale. Thus they may notice individuals, but not populations. Their explanations of evolutionary change, for example, usually rely on direct extensions of their own experiences with human behavioral and morphological plasticity; they describe all individuals as acquiring phenotypic traits by a familiar (e.g. “resistance”, “tolerance”, “immunity”, “sun tan”) mechanism in response to an environmental change or cue. For example, a student explained, “you can’t have like a brown snake in green grass and expect it not to be seen. Sunlight would have a big thing to do with [the color change]. Just like the hot sun, it can fade bright colors or it can tan lighter colors.”
Level 2: Narratives with Hidden Mechanisms – Level 2 students still have many anthropomorphic and anthropocentric elements in their explanations, but fewer than Level 1 students. Students describe organisms in terms of their “jobs” in the environment and place organisms in ecosystem contexts based on the organisms’ “preferences” for general abiotic conditions (e.g. “snakes like to be dry”). Students recognize predator-prey interactions, but not more complex, indirect interactions among organisms and they describe interactions over simplistically in terms of life or death for the individuals involved in the interaction without considering implications at the population level. Students ascribe differences among communities as due to different “conditions” in a vague sense. They begin to recognize more, general or qualitative aspects of the abiotic environment (weather, soils) but tend to describe these as fixed and in terms of being good or bad for organisms or “liked” by them. Students may recognize dispersal through human intervention and/or simplistically think that only migratory species can dynamically move among systems. Students at this level begin to see the effects of disturbances as influential not just at the level of an individual organism, but also at the population level.
Level 3 Principle-Based Reasoning using Phenomenological Narratives – Level 3 students demonstrate a deeper understanding of interactions between organisms and recognize more than just predator-prey interactions. They are aware of how matter and energy are moved as a result of interactions and that individual interactions between organisms have larger implications on populations and contribute to trophic cascades (impacts on organisms more than one step away on a food chain.) Additionally, they can describe an organism’s traits and characteristics of its niche. Level 3 students are able to not only recognize finer dimensions of the abiotic environment (e.g. the amount of water or nitrogen in soil), but also recognize that it can vary over time or space in microhabitats. They are able to explain that life cycles of all organisms include a stage where dispersal to new habitats is likely and can explain how the combination of an organism’s traits and the conditions of their environment limit or facilitate dispersal. However, level 3 students do not integrate abiotic conditions, biotic constraints and dispersal into coherent narratives. They can explain how environment affects a species’ survival, but not how species can modify their environment. For example, a representative student response is “…well, [pythons] can’t affect the weather like we do because it doesn’t really pollute. It doesn’t affect the soil.”
Level 4: Principle-Based Reasoning about Systems across Spatial and Temporal Scales – Level 4 students reason about processes and changes in ecosystems in ways consistent with high school expectations in the NRC Framework. They use populations as units of analysis, recognizing that populations change over time and are distributed in space. They recognize that phenotypic plasticity does not affect hereditary information. Students describe change in populations as happening over generations as the result of differential survival and reproduction, with most young organisms not surviving to adulthood in many species. Students can integrate abiotic constraints, dispersal, and biotic interactions to explain community change over time. Students recognize that organisms can modify their environment.
Our project has developed the following resources for teachers and researchers:
Teaching Materials for Middle and High School Students– Students will explore functional and taxonomic diversity in a stream ecosystem, learn about food web relationships, and learn about the ways in which abiotic and biotic factors determine what organisms are present in a community. Students will make and install leaf packs in a stream, wait for the leaf packs to be colonized by stream organisms, measure abiotic variables that could influence leaf pack colonization, retrieve the leaf packs and classify the organisms they find in both taxonomic and functional ways, and discuss how the leaf pack community is situated within a larger ecosystem.
Learning Goals: The purpose of this unit is to increase students’ ability to apply principles of biodiversity to their observations and reasoning about the natural world, using the freshwater stream ecosystem as the context for learning. This unit focuses on the following principles of biodiversity:
- Organisms vary genetically, thus also vary phenotypically & functionally
- Ecological communities are constrained and shaped by: Biotic resources & interactions, Abiotic resources & conditions, and Dispersal
- Matter and Energy are finite in space and time, and organisms interact with and impact matter and energy resources.
Professional Development Materials
Materials were developed and used with K-12 teachers in California, Colorado, Maryland, and Michigan from 2008-2013. These materials are directed at both content knowledge and pedagogy, with materials focusing on how to use learning progressions while teaching about biodiversity in the classroom. .
Assessment Materials– Open-response assessment items and an annotated key of student performance based on the learning progression
Publications and Presentations
- Doherty, J.H., Hartley, L., Harris, C., and Anderson, C.W., (2014, April). Developing Understanding of Evolution in Complex Contexts. Presented at the annual meeting of the National Association for Research in Science Teaching, Pittsburgh, PA. Powerpoint. Paper.
- Hartley, L., Doherty, J.H., Harris, C., Moore, J.C., Berkowitz, A.R., and Anderson, C.W., (2014, April). Learning Progression Framework and Assessments for Community Ecology. Presented at the annual meeting of the National Association for Research in Science Teaching, Pittsburgh, PA. Powerpoint. Paper.
- Moore, J.C., Hartley, L., Doherty, J.H., Harris, C., Berkowitz, A.R., and Anderson, C.W., (2014, April). Ecological Systems and Learning Progressions: Applications of Basic Principles across Multiple Scales of Organization. Presented at the annual meeting of the National Association for Research in Science Teaching, Pittsburgh, PA. Powerpoint. Paper.
- Wyner, Y. and Doherty, J. H., (2014, April). Unifying Life: Placing Urban Tree Diversity into an Evolutionary Context. Presented at the annual meeting of the National Association for Research in Science Teaching, Pittsburgh, PA. Powerpoint. Paper.
- Doherty, J.H., Hartley, L.M., Harris, C., Anderson, C.W., Berkowitz, A.R., and Moore, J.C. 2013. Using learning progressions to describe how students develop increasingly sophisticated understandings of biodiversity. ESA Meeting, Minneapolis, MN. (download Powerpoint)
- Harris, C., Berkowitz, A., Doherty, J.,& Hartley, L. 2013. Exploring biodiversity’s big ideas in your school yard. Science Scope. (download Paper)
- Harris, C. , Berkowitz, A., Doherty, J., & L. Hartley. 2013. Teaching biodiversity using a learning progression framework and leaf packs. North American Association for Environmental Education, Baltimore, MD.
- Doherty, J., C. Harris, and L. Hartley. 2011. Using stream leaf packs to explore community assembly. Teaching Issues and Experiments in Ecology. http://tiee.esa.org/vol/v7/experiments/doherty/abstract.html
- Doherty, J., J. Schramm, and C. W. Anderson. (April, 2011) The Role of Heredity and Environment in Students’ Accounts of Adaptation by Selection and Phenotypic Plasticity. NARST. ( Powerpoint, Paper)
- Harris, C. and A. Berkowitz. (April, 2011) Using complexity in food webs to teach biodiversity. NARST (Powerpoint, Paper)
- Harris, C., Berkowitz, A. Doherty, J., & L. Hartley. 2011. Environmental Learning Progressions: Biodiversity. National Science Teachers Association, Hartford, CT.
- Harris, C., Berkowitz, A. Doherty, J., & L. Hartley. 2011. Environmental Learning Progressions: Biodiversity. New York State Outdoor Education Association Conference, New York.
- Harris, C., Berkowitz, A. Doherty, J., & L. Hartley. 2011. Environmental Learning Progressions: Biodiversity. Science Teachers Association of New York State, Rochester, NY.
- Hartley, L., C. W. Anderson, A. Berkowitz, J. C. Moore, J. Schramm, S. Simon. (April, 2011) Development of a Grade 6-12 Learning Progression for Biodiversity: an Overview of the Approach, Framework, and Key Findings. NARST. (Powerpoint, Paper)
- Hartley, L., B. Wilke, C. Harris, and J. Schramm. (August, 2012). Student Understanding of Species Diversity in Communities. ESA Annual Meeting. (Powerpoint)
- McMahon, S. and J.C. Moore. (April, 2011) Endangered Species Conservation as a Context for Understanding Student Thinking about Genetic Diversity. NARST. (Powerpoint, Paper)
- Schramm, J and B. Wilke. (April, 2011) Student understanding of species diversity in ecosystems. NARST (Powerpoint, Paper)
- Zesaguli, J., Wilke, B., Hartley, L., Tan, E., Schenk, C., & Anderson, C. W. (2009, April). Developing a K-12 Learning Progression for Biodiversity in Environmental Systems. NARST (download Poster)
Development of these materials was supported by a grant from the National Science Foundation: Targeted Partnership: Culturally relevant ecology, learning progressions and environmental literacy (NSF-0832173). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.