Group items tagged

It is now well known that non-native species have the potential to be harmful to an ecosystem, but that wasn't always the case, and getting rid of non-native invasive species is usually a difficult task. This brief, interrupted case study tells the story of kudzu's introduction into the United States in the late 1800s. It also examines (and even questions) how we define words like "native" versus "non-native" and "invasive" versus "non-invasive." Students will learn how invasive species impact ecosystems and why some non-native species never become established. They also will address questions related to eradicating non-native invasive species. For example, is it okay to attempt to get rid of a non-native species with another non-native species? As part of the activity, students also will have to decide whether or not kudzu should be considered "native" since it has been in the United States since 1876. Originally designed for a general biology course for majors, the case has also been used in a biology class for non-majors as well as an environmental biology class.

This case study introduces students to the "Red Queen Hypothesis." The hypothesis states that when two species compete for a limited resource or exist in a predator-prey relationship, in order for the antagonists to remain in relative population equilibrium, there must be ongoing and reciprocal adaptation on each side. If one species fails to adapt, it may quickly face extinction. Students are introduced to the Red Queen Hypothesis through an excerpt from Lewis Carroll's novel, Through the Looking Glass, in which Alice meets the Red Queen. They then review experiments from the research literature to evaluate the validity of the hypothesis in extant populations.  Students culminate their learning by contrasting their knowledge of the Red Queen Hypothesis to Darwinian evolutionary theory based on a passage from On the Origin of Species.  Students then craft a letter to Darwin helping to explain his "wedge" theory, a notion he originally developed but removed from later iterations of his book due to a lack of experimental evidence. Originally developed for advanced high school biology students, the case also may be used in a college-level introductory course on evolutionary biology.

31min video  The epic voyages of Darwin and Wallace led each to independently discover the natural origin of species and to formulate the theory of evolution by natural selection.

This clicker case addresses several important concepts related to evolution. First, it explores artificial selection and selective breeding. Charles Darwin used artificial selection as an example to support his Theory of Evolution by Natural Selection. Belyaev's Fox-Farm experiment is used as an example of a study that used selective breeding as the primary experimental procedure to investigate changes in a lineage. Second, it addresses an interesting observation made by Charles Darwin in The Origin of Species in which he noted how domesticated species also show interesting traits such as drooping ears which seem to be common in domesticated species. The "Farm-Fox Experiment" not only demonstrates how a research team can thoroughly investigate an intriguing question, but also serves as a classic example of elegant experimental design. Designed for use in a large introductory-level biology class, this case study would also be appropriate for smaller classes as well as for upper-level evolution courses.

The origins of the species known as 'the hobbit' - a human relative only a little over a metre tall - have been debated ever since its discovery in 2004. Now new fossils may reveal the ancestors of this strange species and help us to understand its history.

In the closing sentence of "The Origin of Species," Charles Darwin marvels at the process of evolution, observing how "from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved." Few people would describe bedbugs as most beautiful or most wonderful. Yet this blood-feeding pest may represent an exceptional chance to observe the emergence of Darwin's "endless forms": New research indicates that some bedbugs are well on their way to becoming a new species.

Loss of species richness is often due to anthropogenic activity. The global decline of amphibians is one such example. This case study examines the impact of road deicing agents on amphibians living near bridges and roads treated heavily with salt during the winter months. Concepts explored in this case include changes to the aquatic environment as a result of road deicing applications, bioaccumulation, osmoregulation in amphibians living in clean freshwater, and the impact of increased aquatic salinity levels on the ability of amphibians to adequately osmoregulate in an environment for which they are not adapted. Three short videos created by the author can be shown in class or assigned for viewing in advance for a "flipped" classroom approach. Originally developed for a general education/introductory biology course, the case could also be used with introductory level animal anatomy and physiology courses as part of a deeper exploration of the renal system.

This interrupted case study introduces the topic of bacterial sporulation and cannibalism in Bacillus subtilis. The storyline follows Susan and her lab mates who are presenting research at a lab meeting when Susan falls asleep and dreams they are stranded on a deserted island. She makes connections between their fight for survival in the dream and the survival mechanisms of the bacteria they study in the lab. The benefits of sporulation under conditions of sustained stress are fairly obvious, but Susan's dream is used to examine the idea that sporulation may not always be beneficial and that bacteria would not want to commit to entering such a state in response to temporary stresses. Through the analysis of actual data from the scientific literature, students uncover a mechanism by which B. subtilis delays its commitment to sporulation by killing members of its own species to release nutrients (i.e., cannibalism). Originally developed for a general undergraduate microbiology course when discussing the structure and growth of prokaryotic cells, the case could also be used in an introductory biology course that emphasizes bacteria and data literacy.

This activity supports the HHMI short film The Origin of Species: The Making of a Theory. Students are presented with a map of the Malay Archipelago and some field notebooks with observations of animals. By plotting which animals are found on which island, the students discover the Wallace Line-a sharp boundary that separates distinct Asian and Australian fauna. 

This case study follows two beginning undergraduate researchers on a quest for a summer research project related to food web ecology. While writing their research proposal, the students receive feedback indicating that they have neglected an entire group of organisms from their food web-parasites, which leads them to a scientific research paper discussing how these organisms have been overlooked by scientists studying food webs, the challenges involved with including parasites in food webs, and the contributions parasites ultimately make to food webs. An integrated activity in which students visualize the food web using images of organisms and answer questions about species interactions provides opportunities to examine key concepts such as omnivory, ontogenetic diet changes, trophic levels, complex life cycles, and taxonomic aggregation. This case study was originally written for an undergraduate general ecology course, but could easily be adapted to undergraduate general biology courses covering community ecology or specific courses in invertebrate zoology, parasitology, or disease ecology. The teaching notes also discuss how the included code for R statistical computing software can be used to extend the case study in a more quantitative direction if desired.

web based activity on speciation and adaptive radiation

15 minute video

Lesson materials