Group items tagged

Why does a snake have 25 or more rows of ribs, whereas a mouse has only 13? The answer, according to a new study, may lie in "junk DNA," large chunks of an animal's genome that were once thought to be useless. The findings could help explain how dramatic changes in body shape have occurred over evolutionary history. Scientists began discovering junk DNA sequences in the 1960s. These stretches of the genome-also known as noncoding DNA-contain the same genetic alphabet found in genes, but they don't code for the proteins that make us who we are. As a result, many researchers long believed this mysterious genetic material was simply DNA debris accumulated over the course of evolution. But over the past couple decades, geneticists have discovered that this so-called junk is anything but. It has important functions, such as switching genes on and off and setting the timing for changes in gene activity. 

In this tutorial you will be learning about the Linnaean system of classification used in the biological sciences to describe and categorize all living things.  The focus is on finding out how humans fit within this system.  In addition, you will discover part of the great diversity of life forms and come to understand why some animals are considered to be close to us in their evolutionary history.

Taxonomy, the practice of classifying biodiversity, has a venerable history. Although early natural historians did not recognize that the similarities and differences among organisms were consequences of evolutionary mechanisms, they still sought a means to organize biological diversity.

Human populations have adapted to varying intensities of sunlight with varying tones of skin coloration. The balanced interplay between melanin content and UV absorption allowed populations to successfully migrate from sub-Saharan Africa by influencing levels of two key vitamins: vitamin D and folic acid. This case study explores the evolutionary advantage of different skin tones for the human race; it also emphasizes the absence of scientific evidence for the correlation of abilities, talents, and other complex traits to skin color, and exposes certain social misconceptions linking skin color to specific traits. Although the discussion of race is not always a comfortable fit for science and biology courses, this case study uses the topic as an inherently interesting and important subject for applying basic biological concepts of DNA, the central dogma, and mutations to real world questions of physical difference and skin color. This case has been used in biology courses for non-science majors but would also be appropriate for advanced high school students.

In just 15 years, the lizards' heads have grown larger-an adaptation that allows them to eat a wider assortment of insects made available by the dam's creation. The find may portend other rapid evolutionary changes across the globe as humans continue to dramatically alter the natural landscape.  

A paper published today in Science Advances just might change that. By creating a reliable method of studying viruses' long evolutionary history-hitherto nearly impossible-researchers have found new evidence that strongly suggests viruses are indeed living entities.

How can a mixture of molecules, too small to be seen with even a high-powered microscope, be separated from one another? Such was the dilemma facing scientists until the development of a process that is now standard in laboratories worldwide-gel electrophoresis. Laboratories rely heavily on this proven and reliable technique for separating a wide variety of samples, from DNA used in forensics and for mapping genes, to proteins useful in determining evolutionary relationships.

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.

We know poisonous snakes are dangerous, but what exactly makes venom so powerful? Evolutionary biology tells us why venom is useful for snakes, but chemistry tells us how venom works. This week, Reactions sheds some light on the proteins in venom, as well as its potential medical uses

Great video footage

his resource describes an inquiry-based, in-class exercise designed for students working in small groups. It is designed to review and enrich student understanding of probability, how probabilities of individual events can be combined to make predictions about more complex outcomes, and how observed data can be compared to a null model based on probabilities using a chi-squared test. These skills are used extensively for classical genetic analysis. Throughout the activity, peers and instructors guide students through the process of developing and solving problems using probabilities and chi-squared tests in small groups.