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
Species richness Last Updated on 2014-11-09 19:13:40 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 »
Species range limits Last Updated on 2014-11-09 18:49:44 Species range limits (SRLs) are defined as the spatial boundaries beyond which no living individuals of a given species occur.  Populations occurring near or at SRLs are often referred to as “marginal,” “peripheral,” “edge,” or “border” populations.  SRLs may represent areas beyond which individuals cannot physiologically tolerate ecological conditions or areas where they have not yet dispersed.  SRLs may be stable (i.e., at equilibrium) or may represent areas where range expansion through migration or population growth is in the process of occurring.  SRLs are significant to ecology, evolution, and conservation for several reasons.  They provide opportunities to understand the conditions under which populations expand or contract, and the conditions under which populations may evolve new forms. Additionally, SRLs... More »
Mammal Last Updated on 2014-10-15 22:58:09   Mammalia is a group of warm-blooded, air breathing vertebrates. With the common name mammal, each species is endowed with the characteristic of fur and three-boned middle ear; but the most remarkable element of group identity is an advanced brain element known as the neocortex, that functions as a center of complex cognition; no species except mammals have this well defined brain structure. Having pronounced inherent sexual dimorphism, the females have mammary glands capable of producing milk. There are approximately 5400 described mammalian species comprising around 1200 genera. Mammals span a size range from the three centimeter Bumblebee Bat to the 33 meter long Blue Whale. Feeding habits vary widely among species, including carnivores and insectivores who prey on animals, to frugivores and granivores who eat fruit or seeds. Earliest mammals arose approximately 200 to 130... More »
Species Last Updated on 2014-09-15 11:53:19 A species is a group of organisms capable of interbreeding and producing fertile offspring of both genders, and separated from other such groups with which interbreeding does not characteristically occur: however, for asexual organisms, a distinct species may be considered a collection of organisms which have very similar DNA or physical characteristics. Certain species are further subdivided into subspecies. The early Greeks and Romans had a well established set of taxonomic names for species of animals and plants, based upon the macroscopically observable characteristics of organisms, with Aristotle being the chief architect of this codification; even earlier, the Egyptians and Cretans developed basic symbols and names for species important in farming and culture. It was not until the year 1686 when English naturalist John Ray introduced the concept that species were... More »
Gymnosperm Last Updated on 2014-09-06 20:29:55 A gymnosperm is one of a number of non-flowering seed bearing vegetation species, including conifers, cycads, Ginkgo and Gnetales.  These species arose first in the Carboniferous Period. The word gymnosperm derives from the Greek root gymnospermos for naked seed, meaning the exposed presentation of their ovules prior to fertilization. This naked seed condition differs from the seeds of angiosperms (flowering plants), which are enclosed during pollination. Seeds of the gymnosperm develop on the surface of scale or leaf-like appendages of cones. Gymnosperms first appeared in the late Carboniferous Period, although precursor characteristics of seed plants were evident in fossil progymnosperms from the late Devonian Period aproximately 380 million years before present. Within the mid-Mesozoic period, pollination of some extinct groups of gymnosperms were by extinct species of... More »