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This "clicker case" gives students an opportunity to apply their understanding of three different types of selection (directional, stabilizing, and disruptive) to a variety of model systems. The case describes each type of selection in detail, presents a paradigm case of each, and then uses clicker questions to test whether students can identify the mode of selection in other systems (answers included in the teaching notes).  Nine different studies are presented so that students gain a broad understanding of selection and how environmental factors can impact species differently. The case concludes with an optional discussion activity (also discussed in the teaching notes) to deepen understanding. Although designed for a high school classroom, it could easily be used in a lower-level college course as an engaging introduction or review of concepts. The case could be used at the beginning of an evolution unit, but it would be helpful if the students were familiar with natural selection before completing the activity.

The theory of evolution by natural selection is simple, elegant, and profound. Yet, a large number of undergraduate students including biology majors, medical students, and pre-service science teachers maintain a large set of misconceptions that interfere with a solid understanding of the process of natural selection. It is also well known that lecturing is an insufficient strategy to help students confront and correct these misconceptions. This activity uses the evolution of coat color in oldfield mice (Peromyscus polionotus) as the basis of a case study in which students investigate the role of variation, heritability, and selection in the evolution of a trait. Students examine graphs, data, and excerpts from a series of papers that have been published about this system over the last 100 years. The content is delivered as an interrupted case and encourages peer-to-peer teaching and interaction. The case is appropriate for use in non-major, introductory, or advanced biology courses.

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.

Discover natural selection as a mechanism of evolution with the Amoeba Sisters. This video also uncovers the relationship of natural selection and antibiotic resistance in bacteria.

Discover natural selection as a mechanism of evolution with the Amoeba Sisters. This video also uncovers the relationship of natural selection and antibiotic resistance in bacteria.

A keenly observant young man named Tony Allison, working in East Africa in the 1950s, first noticed the connection and assembled the pieces of the puzzle. His story stands as the first and one of the best understood examples of natural selection, where the selective agent, adaptive mutation, and molecule involved are known-and this is in humans to boot. The protection against malaria by the sickle-cell mutation shows how evolution does not necessarily result in the best solution imaginable but proceeds by whatever means are available.

This hands-on activity, used in conjunction with the film The Making of the Fittest: Natural Selection in Humans, teaches students about population genetics, the Hardy-Weinberg principle, and how natural selection alters the frequency distribution of heritable traits. It uses simple simulations to illustrate these complex concepts and includes exercises such as calculating allele and genotype frequencies, graphing and interpretation of data, and designing experiments to reinforce key concepts in population genetics.

Biologists have long puzzled about how evolutionary selection, known for its ruthless requirement for efficiency, allows the existence of males - when in so many species their only contribution to reproduction are spermatozoa. But research published today in Nature shows that sexual selection - when males compete and females choose over reproduction - improves population health and protects against extinction, even in the face of genetic stress from high levels of inbreeding.

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 case is an exploration of the process of natural selection using white clover (Trifolium repens) as an example. In general, two forms of white clover can be found around the world in various habitats. One type is able to produce cyanide in its leaves, while the other is not. This variation within the clover species, along with the fact that cyanide production is paired with the production of a white stripe on the leaf, is used to teach the process of evolution through natural selection. 

simulation of natural selection 

Middle and high school students need an opportunity to construct evidence-based explanations for how variation and natural selection can lead to adaptation of populations over time (NGSS MS-LS4-4 and HS-LS4-4). However, managing a population of classroom-friendly living organisms that consistently grow, develop, and thrive while students observe variation among individuals can be a real challenge.

The life science/biology course is divided into 12 instructional segments grouped into four sections. In the first section, From Molecules to Organisms: Structures and Processes, students develop models of how molecules combine to build cells and organisms (IS1 [Structure and Function]; IS2 [Growth and Development of Organisms]; IS3 [Organization for Matter and Energy Flow in Organisms]). In the second section, Ecosystems: Interactions, Energy, and Dynamics, students zoom out to the macroscopic scale to show how organisms interact (IS4 [Interdependent Relationships in Ecosystems]; IS5 [Cycles of Matter and Energy Transfer in Ecosystems]; IS6 [Ecosystem Dynamics, Functioning, and Resilience]; IS7 [Social Interactions and Group Behavior]). Students return to the role that DNA plays in inheritance during the third section, Heredity: Inheritance and Variation of Traits (IS8 [Inheritance of Traits]; IS9 [Variation of Traits]). The class ends tying together interactions at all these scales by explaining evolution and natural selection in Biological Evolution: Unity and Diversity (IS10 [Evidence of Common Ancestry and Diversity]; IS11 [Natural Selection]; IS12 [Adaptation and Biodiversity]). A vignette in IS12 illustrates the level of three-dimensional understanding students are expected to exhibit as a capstone of the course.

In their study of the medium ground finches, evolutionary biologists Peter and Rosemary Grant were able to track the evolution of beak size twice in an amazingly short period of time due to two major droughts that occurred in the 1970s and 1980s. This activity simulates the food availability during these droughts and demonstrates how rapidly natural selection can act when the environment changes. Students use two different types of tools to represent different beak types to see which is best adapted to collect and "eat" seeds of different sizes. Students collect and analyze data and draw conclusions about traits that offer a selective advantage under different environmental conditions. They have the option of using an Excel spreadsheet to calculate different descriptive statistics and interpret graphs.

Researchers analysed the genomes of 51 individuals who lived between 45,000 years ago and 7,000 years ago. The results reveal details about the biology of these early inhabitants, such as skin and eye colour, and how different populations were related. It also shows that Neanderthal ancestry in Europeans has been shrinking over time, perhaps due to natural selection. The study in Nature journal shines a torchlight over some 40,000 years of prehistory, showing that ancient patterns of migration were just as complex as those in more recent times.

Introductory Activity in evolution unit; typically adapt to design a moth (no other instructions), select a student predator, attach the moths, let the predator in, repeat twice, then design a moth and model a natural disaster by moving to a different habitat (hallway).

Bozeman video 10:26 Paul Andersen explains how life has evolved and continues to evolve today. A brief discussion of artificial, natural and sexual selection is included. The beak of the finch is used to explain how directional selection is achieved.

In most animals, the drive to breed and produce offspring is strong. However, most males live their whole lives without having the chance to breed. The events leading up to mating can be very dangerous and also very costly to an individual. Some males have evolved elaborate structures, or weapons, as a result. The structures do help males in both combative situations and with attracting females, but ironically, the structures themselves come with certain costs. This flipped case study provides students with the opportunity to not only see how animal structures and functions are linked, but also to see how certain animal structures are needed and costly. There are videos that students are expected to view before the case. The case was initially designed for a second semester college general biology class for majors. However, it can also be used in non-major biology classes. Students should have some background knowledge of natural selection, specifically sexual selection as well as energetic demands of certain structures.

This clicker case addresses several concepts related to the evolutionary ecology of herbivore defenses. A survey of several different studies that investigated chemical defenses in Thymus vulgaris (thyme) gives students the opportunity to develop hypotheses, pose potential experiments, and interpret data to develop a better understanding of not only herbivore deterrence, but also how natural selection can involve different pressures selecting for different phenotypes. The case study incorporates group discussion, analysis of experimental design, and data evaluation as central activities. It can be taught in a single 50-minute class session, an economy that is achieved in part by using a "flipped" approach. Students prepare outside of class by watching several short videos (one of which was made by the author) that teach the basics of herbivore deterrence and abiotic and biotic forces in the environment that can influence plant adaptations. The case study was designed for use in a large introductory-level class, but would also be appropriate for smaller classes or upper-level evolution courses.