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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.

This directed case study in PowerPoint format focusses on the London Underground Mosquito, Culex molestus, and its potential relationship to the common mosquito, Culex pipiens, in order to explore the topics of evolution, reproductive isolation, and speciation. As the story unfolds, the case mirrors the process of science. The students receive some initial data and observations collected by Byrne and Nichols in London. Based on these observations, the students then form a hypothesis and design an experiment. Finally, they receive more data collected by Becker et al. and draw conclusions.

15. That's all you need to know about the measles. OK, that's not true at all. There's no one weird trick that will give you a flat belly (besides lying face-down on something flat), and there's no one weird number that explains measles epidemiology. But the basic reproduction number, or R0, of a disease does shed some light on which diseases become epidemics and how we can keep them in check.

The virtual lab includes four modules that investigate different concepts in evolutionary biology, including adaptation, convergent evolution, phylogenetic analysis, reproductive isolation, and speciation. Each module involves data collection, calculations, analysis and answering questions. The "Educators" tab includes lists of key concepts and learning objectives and detailed suggestions for incorporating the lab in your instruction.

" The typical naked mole rat lives 25 to 30 years, during which it shows little decline in activity, bone health, reproductive capacity and cognitive ability. What is the secret to this East African rodent's long, healthy life?"

This case study explores the recent (2010 - 2016) outbreak of neural tube defects, specifically anencephaly, in a rural three-county region of Washington state, particularly Yakima, WA. The case study focuses on the biological aspects of teratogens that may cause birth defects as well as epidemiological investigations of disease outbreaks. By the end of the case, students will have explored how our environment may have severe biological consequences on the human body during pregnancy and will have evaluated governmental and scientific investigations of a rare outbreak of birth defects. This clicker case study was developed for a non-majors biology course entitled "Human Development: Conception to Birth," although it could be taught in any introductory biology course for majors or non-majors during a unit on human reproductive biology or developmental biology. The case assumes that students have no prior knowledge of developmental biology or birth defects. The case study could also be adapted for upper-division courses by getting more in-depth on the specifics of teratogen mechanisms, the developmental biology and physiology of neural tube defects, or more complex epidemiological analyses.

This is the updated Amoeba Sisters human organ systems video, which provides a brief introduction to each of the 11 human organ systems including the circulatory, digestive, endocrine, excretory, integumentary, lymphatic/immune, muscular, nervous, reproductive, respiratory, and skeletal systems.

To address this issue, we have developed case studies that track the evolution of traits from their origination in DNA mutation, to the production of different proteins, to the fixation of alternate macroscopic phenotypes in reproductively isolated populations.

Article summarizing cell division with time lapse cell division video of 30hours pro vs eukaryotic division.

Dogs are excellent models for studying genetics, especially disease genetics. Work done in the last 20 years has shown that dogs share many gene-related disorders with people. Each breed is a closed reproductive population with distinct rates of heritable diseases, which dramatically increases the odds of finding disease-related loci. In creating new dog breeds, we reduce the gene pool within those populations, and fix many alleles. This homogeneous background makes it much easier to map QTLs and perform linkage analyses

The anole lizards of the Caribbean islands represent a group of about 150 closely related species, most of which evolved within the past 50 million years from a single colonizing species. Different processes, including geographic isolation, adaptation to different environments, and reproductive isolation, play a role in anole speciation. 

Before civilization began to impact the human life cycle approximately 10,000 years ago, human beings had high birth and death rates. Today the world is in the midst of a demographic transition - a transition to low birth and death rates - as the ability to control both disease and reproduction increases. Along the way, between these extremes, populations go through an intermediate period of continued high birth rates, combined with low death rates, resulting in a population explosion.

A complete understanding of evolution requires knowledge that spans many biological sub-disciplines. However, students are often taught evolution in the context of ecological systems and isolated from genetic and cellular ones. To address this issue, we have developed case studies that track the evolution of traits from their origination in DNA mutation, to the production of different proteins, to the fixation of alternate macroscopic phenotypes in reproductively isolated populations.

The Y chromosome is only one-third the size of the X. Although the Y has a partner in X, only the tips of these chromosomes are able to recombine. Thus, most of the Y chromosome is inherited from father to son in a pattern resembling asexual, not sexual, reproduction. No recombination means no reassortment, so deleterious mutations have no opportunity to be independently selected against. The Y chromosome therefore tends to accumulate changes and deletions faster than the X. Degradation doesn't occur in X chromosomes because during female meiosis, the X has the other X as a full partner in recombination.

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.

IN recent weeks, two major medical organizations have issued independent warnings about toxic chemicals in products all around us. Unregulated substances, they say, are sometimes linked to breast and prostate cancer, genital deformities, obesity, diabetes and infertility. "Widespread exposure to toxic environmental chemicals threatens healthy human reproduction," the International Federation of Gynecology and Obstetrics warned in a landmark statement last month.

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.

Researchers have long known that women whose families include fraternal twins are more likely to give birth to twins themselves, and they're finally starting to figure out why. After scanning data from nearly 2000 mothers of fraternal twins, scientists from eight countries found two genes that increase a woman's chance of having twins-one that affects hormone levels and another that may alter how ovaries respond to them. The second of these may also have implications for why some women respond better than others to in vitro fertilization.

"Online biology games for school aged kids. Play FREE, fun and interactive online biology games to help you study for biology exams, tests, quizzes. There are over 10 types of play offered as classroom biology games. Use these as fun review games for tests or to just to increase your general biology / living environment knowledge. These science games make learning fun! These also make great living environment games as the curriculum is very similar to biology."

BBC News: Quick Guide: Cloning  Succinct sections on key aspects of cloning