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This case study uses an interactive activity to illustrate density dependence in ecology classes. We developed a "hunt" using paper butterflies with warning signals on the upper side of the wings and symbols that indicate if a butterfly is noxious underneath the wings. Butterflies are distributed in four different patches with varying densities of noxious and palatable butterflies, simulating Batesian or Müllerian mimicry. Students can catch as many butterflies they want for a period of time, but if they catch more than three noxious butterflies they are out of the game. After the activity, students calculate the survival rate of each type of butterfly in each patch and discuss the implications of density and warning signals according to their results. Students then answer questions and build graphs using the data from the activity and knowledge from the class and the discussion. With this case study, students will be able to understand negative and positive density dependence, as well as predation, learning, and convergent evolution, while recalling or being introduced to Batesian and Müllerian mimicry.

It turns out that some monkeys make better hunting partners than prey. That's the case on the Ethiopian highlands, where two unusual species have developed an equally unusual co-dependency. The relationship benefits both canine and primate, although at least one or two nearby rodent species might regret it.

In the deep, dark ocean, many sea creatures make their own light for hunting, mating and self-defense. Bioluminescence expert Edith Widder was one of the first to film this glimmering world. At TED2011, she brings some of her glowing friends onstage, and shows more astonishing footage of glowing undersea life.

This case study was developed to teach students the importance of understanding the behavior of wildlife, explore the difficulty in making management decisions when the public is invested in a species, and to help students develop critical thinking and public speaking skills. Students learn about the conservation status and behavior of the black rhinoceros by reading a primary literature article and answering a series of questions. They then listen to a Radiolab podcast that explores the moral dilemma of whether it is ethically appropriate to shoot an endangered rhinoceros if the purpose is to raise conservation funds. Students are assigned one of five positions and write essays to prepare for a town hall style debate in which they examine the pros and cons of such a decision. The Radiolab podcast is based on real events, and is also representative of many ethical dilemmas that wildlife managers regularly face. This case study is appropriate for several upper division biology courses.

In our first animation of this series we learned how point mutations can edit genetic information. Here we see how duplication events can dramatically lengthen the genetic code of an individual. As point mutations add up in the duplicated region across generations, entirely new genes with new functions can evolve. In the video we see three examples of gene duplications resulting in new traits for the creatures who inherit them: the evolution of a venom gene in snakes, the evolution of leaf digestion genes in monkeys, and the evolution of burrowing legs in hunting dogs.

How does a Killer T Cell Kill its target? Our new film captures the behaviour of cytotoxic T cells - the body's 'serial killers' - as they hunt down and eliminate cancer cells before moving on to their next target.

Lyme disease, Ebola and malaria all developed in animals before making the leap to infect humans. Predicting when such a 'zoonotic' disease will spark an outbreak remains difficult, but a new study suggests that artificial intelligence could give these efforts a boost. A computer model that incorporates machine learning can pinpoint, with 90% accuracy, rodent species that are known to harbour pathogens that can spread to humans, researchers report this week in the Proceedings of the National Academy of Sciences1. The model also identified more than 150 species that are likely to be disease reservoirs but have yet to be confirmed as such.

At first glance, the research of Bonnie Bassler and Baldomero "Toto" Olivera might not appear to be medical at all. Dr. Bassler works on marine bacteria that glow in the dark, while Dr. Olivera studies venomous snails that hunt by harpooning fish. Yet their findings show what science has revealed time and again-knowledge that can be used to unlock medical secrets is often hidden in unlikely places. Nature has much to teach us, as long as we know where to look and what to look for. Join us for a four-lecture series as Bonnie and Toto guide us through intriguing slices of the natural world revealing how a deeper understanding of nature and biodiversity informs their research into new medicines.

The hollow Cola tree growing in a remote area of southeastern Guinea was once home to thousands of bats routinely hunted and killed by the neighborhood children. It was also a popular spot to play. A year ago, one child in particular lived within fifty meters of the tree: a two-year-old boy who died in December 2013 and later was identified as the first person in west Africa known to have developed Ebola.

The many forms of dogs that exist today were all created through selective breeding from the dog's ancestor, the wolf. In a span of less than 10,000 years, breeders have changed traits and body shapes of dogs by artificial selection-for example, emphasizing different aspects of hunting and herding behavior.

Squirrels are frequent and beloved residents of college campuses throughout the United States, but oftentimes less welcomed by campus maintenance officials who report squirrels nesting in buildings, interfering with airflow from heating and cooling units, and destroying gutters. In this laboratory case, students act as members of a fictitious "squirrel task force" appointed by their campus administrators to provide recommendations for how to manage their school's squirrel population.  Students work in groups to assess the habitat suitability of their campus for squirrels by identifying and measuring trees that provide seasonal food for squirrels, and by identifying desirable hunting perches for common squirrel predators.  Students conduct squirrel surveys in designated campus zones to calculate the number of squirrels per acre on their campus and compare it with mean squirrel densities reported in forested areas and at a rival institution.  Students then compile and synthesize class data to provide management recommendations for university maintenance officials for either increasing or decreasing campus squirrel populations. Originally developed for an undergraduate wildlife biology course, the case could also be used in a lower-division biology or environmental studies course.