Evolutionary Biology

  • Evolution in Action Featured Article Evolution in Action Evolution in Action

    ?Main Image: Scientists have found a population of tropical butterflies that may be on its way to splitting into two distinct species based on wing color and mate preference.... More »

  • Extremophile Featured Article Extremophile Extremophile

    An extremophile is an organism adapted to unusual limits of one or more abiotic factors in the environment. Some of the extreme conditions are temperature, pH, high salinity,... More »

  • Pliocene Featured Article Pliocene Pliocene

    Editor's note: The Pliocene is the period of the geologic timescale that spans the era from approximately 5.331 to 2.588 million years ago. It preceeds the Pleistocene... More »

  • DNA Featured Article DNA DNA

    Deoxyribonucleic acid (DNA) is a long chain organic molecule that contains the coding for all metabolic and reproductive processes of all living organisms, save for certain... More »

  • Edenic Period Featured Article Edenic Period Edenic Period

    The Edenic Period is a span of time in which prehistoric speciation and extinction rates were deemed to be in average long term equilibrium, before the ascent and influence of... More »

  • Adaptations of desert birds and mammals Featured Article Adaptations of desert birds and mammals Adaptations of desert birds and mammals

    Have you ever wondered how animals can live in a hostile desert environment? Water, so necessary for life processes, is often scarce. Temperatures, which range from freezing to... More »

  • Virus Featured Article Virus Virus

    A virus is a microscopic organism that can replicate only inside the cells of a host organism. Most viruses are so tiny they are only observable with at least a conventional... More »

  • Fern Featured Article Fern Fern

     A fern is any one of a group of about 12,000 species of vascular plants[1] Lacking flowers and seeds, ferns reproduce by spores; otherwise, ferns have the major... More »

  • Epigenetics: The Science of Change Featured Article Epigenetics: The Science of Change Epigenetics: The Science of Change

    Researchers, physicians, and others have investigated the dark crevices of the gene, trying to untangle clues that might indicate that gene function could be altered by more... More »

Recently Updated
Amphibian ecology and evolution Last Updated on 2014-07-23 18:38:53 Amphibians are found in ponds, streams, wetlands of all types, under rotten logs, in leaf litter, in trees, underground, even in pools of rain water inside large leaves. However, they are not able to osmoregulate in salt water and, therefore, are not found in the ocean. Although some amphibians defy the rules and thrive in cold or dry conditions, the group reaches its highest diversity and numbers in warm, humid climates.  In the wet tropics, amphibians remain active all year around, but in the temperate zone, winter temperatures cool their bodies, forcing them to become inactive. In the autumn, environmental cues direct amphibians to find moist, sheltered places like muddy pond bottoms or deep leaf litter to hibernate. The wood frog (Rana sylvatica) has the most northerly range of any amphibian, crossing the Arctic circle, into the Mackenzie River valley in the Northwest... More »
Species richness Last Updated on 2014-07-02 14:24:39 Species richness is simply the number of species present in a sample, community, or taxonomic group. Species richness is one component of the concept of species diversity, which also incorporates evenness, that is, the relative abundance of species. Species diversity is one component of the broader concept of biodiversity. About 1.75 million living species and 300,000 fossil species have been described by scientists. Estimates of the total species richness of the Earth range from three to 10 million, with some estimates as high as 50 million. Patterns of species richness can be observed at a variety of levels. The causes of these patterns remain active areas of research in ecology, biogeography, and evolutionary biology. Some taxonomic groups of organisms have more species than other groups. For example, there are almost three times more species of beetles (Order Coleoptera) than... More »
Pleistocene Last Updated on 2014-07-02 14:12:09 This article on the Pleistocene Epoch was written by P. D. P, Brian R. Speer and Ben Waggoner. The mammoth was one of the largest land mammals of the Pleistocene, the time period that spanned from 1.8 million to approximately 10,000 years ago. Pleistocene biotas were extremely close to modern ones — many genera and even species of Pleistocene conifers, mosses, flowering plants, insects, mollusks, birds, mammals and others survive to this day. Yet the Pleistocene was also characterized by the presence of distinctive large land mammals and birds. Mammoths and their cousins the mastodons, longhorned bison, sabre-toothed cats, giant ground sloths, and many other large mammals characterized Pleistocene habitats in North America, Asia, and Europe. Native horses and camels galloped across the plains of North America. Great teratorn birds with 25-foot wingspans stalked prey. Around the... More »
Cells Last Updated on 2014-06-30 14:15:10 Cells are the smallest component of the body that can perform all of the basic life functions. Each cell performs specialized functions and plays a role in the maintenance of homeostasis. While each cell is an independent entity, it is highly affected by damage to neighboring cells. These various cell types combine to form tissues, which are basically collections of specialized cells that perform a relatively limited number of functions specific to that type of tissue. The human body is made up of several trillion cells; these cells are of various types, which can differ greatly in size, appearance and function.   While there are approximately 200 types of cells, they all have similar features: cell membrane, cytoplasm, organelles, and nucleus. The only exception is that the mature red blood cell does not contain a nucleus. In general, toxins can injure any of the components of... More »
Altruistic behaviors Last Updated on 2014-06-23 18:00:42 Altruistic traits are traits that reduce the fitness (survival or reproduction) of the individual with the trait (known as the “actor”) while increasing the fitness of other individuals (known as the “recipients”). A classic example of an altruistic behavior is the “warning call” given by many species of animals including ground squirrels, prairie dogs, and passerine birds. If an individual observes an attacking predator it may give a call that has two effects. First, when other nearby individuals hear the call they recognize that danger is near and flee to safety. Individuals that hear the early warning (the recipients) benefit by having a decreased chance of being killed by the predator. However, by giving the warning call, the caller (the actor) delays his/her opportunity to flee to safety and attracts the attention of the predator, thus... More »