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This interactive explores different anatomical features of the human body and what they reveal about the evolutionary history we share with other organisms, including earlier, long-extinct species.

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.

article with paired images- Convergent evolution is the process by which unrelated or distantly related organisms evolve similar body forms, coloration, organs, and adaptations. Natural selection can result in evolutionary convergence under several different circumstances. Species can converge in sympatry, as in mimicry complexes among insects, especially butterflies (coral snakes and their mimics constitute another well-known example).

Gene flow is the transfer of genetic material between separate populations. Many organisms are divided into separate populations that have restricted contact with each other, possibly leading to reproductive isolation. Many things can fragment a species into a collection of isolated populations. For example, a treacherous mountain pass may cut off one herd of mountain goats from another. In human beings, cultural differences as well as geographic separation maintain unique populations: It is more likely that a person will marry and have children with someone who lives nearby and speaks the same language.

This interrupted case study addresses several concepts related to climate change and its effect on the American pika. Often called an indicator species for climate change, the pika has a unique set of variables specific to its environment. Factors such as temperature, snowpack, and vegetation can affect the distribution and ultimately the chances of survival. The case was designed for use in a "flipped" classroom in which students prepare in advance outside of class by filling out a worksheet while watching a video. The video, created by the author of the case, provides students with baseline information that they apply in class to come up with key ideas and predictions, followed by analysis of actual data to test the hypotheses they develop. The case study incorporates group discussion, analysis of experimental design, and data evaluation as central activities and can be taught in a single 50 minute class session. The case was designed for use in a large introductory-level class, but is also appropriate for smaller classes.

As the genomes of more and more species are sequenced, geneticists are piecing together an extraordinarily detailed picture of the molecules that are fundamental to life on Earth. With modern techniques, we can not only trace how the bodies of animals have evolved, we can even identify the genetic mutations behind these changes and, as we recently reported, genes sometimes evolve in surprising ways. Here though, in celebration of the versatility of DNA, New Scientist presents five classic examples of gene evolution.

In population genetics, gene flow (also known as gene migration) is the transfer of alleles or genes from one population to another. Migration into or out of a population may be responsible for a marked change in allele frequencies (the proportion of members carrying a particular variant of a gene). Immigration may also result in the addition of new genetic variants to the established gene pool of a particular species or population.

Paul Strode describes the HHMI BioInteractive Click and Learn activity on DNA sequencing and phylogenetic trees. He describes how it teaches students DNA sequence alignment, and how those sequence differences allow researchers to determine relationships between species. Visit www.biointeractive.org/phylo-tree to use the interactive resource, and to find related materials. Subscribe to the BioInteractive YouTube channel to get the latest educator tips!

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.

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.

7:41 Explores classification in biology as well as taxonomy hierarchy: domain, kingdom, phylum, class, order, family, genus, and species with The Amoeba Sisters! This video also discusses the importance of scientific names and why classification can have major changes due to DNA and cell structure evidence.

In 1950, Erwin Chargaff published a paper stating that in the DNA of any given species, the ratio of adenine to thymine is equal, as is the ratio of cytosine to guanine. This became known as Chargaff's ratio, and it was an important clue for solving the structure of DNA.

This case study teaches students about allopatric speciation through an investigation of the benthic and limnetic sticklebacks of Paxton Lake, which are among the youngest species on Earth, diverging from each other after the Pleistocene glaciers melted and the Gulf Islands formed. Researchers at the University of British Columbia have carried out a variety of fascinating studies on these hardy little fish. Results from this research (formatted as data sheets included in the teaching notes) are provided to students who design experiments and then compare actual data to investigate why benthic and limnetic sticklebacks seldom interbreed in Paxton Lake. Developed for a first-year biology course for majors organized around the general theme of evolution and the history of life on Earth, this case study is an updated version of another case in the collection, "Something's Fishy in Paxton Lake" (Sharp, 2001). The current version is especially suited for a flipped classroom in which students prepare for class ahead of time with a reading assignment that also involves the viewing of a video by the case authors that introduces the mechanisms of allopatric speciation.

Now, a new study reports that at least one species of songbird-and likely many more-already knows how to prep its chicks for a warming world. They do so by emitting special calls to the embryos inside their eggs, which can hear and learn external sounds. This is the first time scientists have found animals using sound to affect the growth, development, behavior, and reproductive success of their offspring, and adds to a growing body of research revealing that birds can "doctor" their eggs.

"That changed when NASA created the Landsat program, a series of satellites that would perpetually orbit our planet, looking not out but down. Surveillance spacecraft had done that before, of course, but they paid attention only to military or tactical sites. Landsat was a notable exception, built not for spycraft but for public monitoring of how the human species was altering the surface of the planet."

This interrupted case study is designed to introduce beginning biology students to the process of science by exploring a question that is accessible to students with limited scientific background. The giraffe (Giraffa camelopardialis) is the tallest terrestrial mammal and has a disproportionally long neck. Historically, this trait has been hypothesized to be an adaptation for competition between the giraffe and other herbivore species. Guided by a PowerPoint presentation and (optional) worksheet, students will propose hypotheses to explain the giraffe's uniquely long neck and will examine the results of field experiments to test the prevalent historical hypothesis that the long neck allows the giraffe to exploit high food sources. They will find that the data do not support this initial hypothesis and will use other field observations to propose and examine an alternative hypothesis. Throughout the activity students will engage in the process of science; they will propose hypotheses, design experiments, make predictions, and draw conclusions from published field observations.

The data comes from the open Tree of Life Project, a collaboration among biologists and other scientists around the world. It contains decades' worth of work in phylogeny, evolutionary history of and relationships among groups of organisms. The project is about a year away from a complete tree of all life, Rosindell said. He wanted a system in place that could visualize it as soon as it's ready. Right now, OneZoom only contains mammals, but that's still more than 5,000 species, all correlated with each other and color-coded according to their threat levels. Rosindell has big plans for the rest, and he even wants to build a searchable app for smartphones, showcasing the history and relationships between all life on Earth.

web based activity on speciation and adaptive radiation

Conservation science game, predator-prey relationships, habitat protection

Japanese knotweed (Fallopia japonica) is an invasive plant that can be very hard to eliminate. This PowerPoint-driven case study briefly describes this plant and asks students to identify possible solutions for its control when a homeowner discovers it growing next to his house. The case was designed for an introductory college course, either a general biology course or a plant biology course, and while it can be used as a regular case, it was actually written to assess the students' ability to solve a problem and write an analysis. If you teach with cases, shouldn't you test with cases as well?