adaptive radiation

Examples of adaptive radiation in the following topics:

• Allopatric Speciation

  • Typically, environmental conditions, such as climate, resources, predators, and competitors for the two populations will differ causing natural selection to favor divergent adaptations in each group.
  • This is called adaptive radiation because many adaptations evolve from a single point of origin, causing the species to radiate into several new ones.
  • Island archipelagos like the Hawaiian Islands provide an ideal context for adaptive radiation events because water surrounds each island which leads to geographical isolation for many organisms.
  • The Hawaiian honeycreeper illustrates one example of adaptive radiation.
  • The honeycreeper birds illustrate adaptive radiation.

• Loss of Biodiversity

  • The cichlids of Lake Victoria are the product of an adaptive radiation.
  • An adaptive radiation is a rapid (less than three million years in the case of the Lake Victoria cichlids) branching through speciation of a phylogenetic tree into many closely-related species; typically, the species "radiate" into different habitats and niches.
  • The Galápagos finches are an example of a modest adaptive radiation with 15 species.
  • The cichlids of Lake Victoria are an example of a spectacular adaptive radiation that includes about 500 species.

• Post-Cambrian Evolution and Mass Extinctions

  • The post-Cambrian era was characterized by animal evolution and diversity where mass extinctions were followed by adaptive radiations.
  • As animal phyla continued to diversify, new species adapted to new ecological niches.
  • Continual changes in temperature and moisture throughout the remainder of the Paleozoic Era due to continental plate movements encouraged the development of new adaptations to terrestrial existence in animals, such as limbs in amphibians and epidermal scales in reptiles.
  • Plants, too, radiated into new landscapes and empty niches, creating complex communities of producers and consumers, some of which became extremely large on the abundant food available.
  • In the following Cenozoic Era, mammals radiated into terrestrial and aquatic niches once occupied by dinosaurs.

• Increased Cancer Risk from Radiation

  • Up to 10 percent of invasive cancers are related to radiation exposure, including both ionizing radiation and non-ionizing radiation.
  • Up to 10 percent of invasive cancers are related to radiation exposure, including both ionizing radiation and non-ionizing radiation.
  • The most widely accepted model posits that the incidence of cancer due to ionizing radiation increases linearly with effective radiation dose at a rate of 5.5 percent per sievert.
  • If the linear model is correct, natural background radiation is the most hazardous source of radiation to the general public health, followed closely by medical imaging.
  • The development of cancer can be divided into three major stages: morphological changes to the cell, acquisition of cellular immortality, and adaptations that favor tumor formation.

• Extremophiles and Biofilms

  • Prokaryotes are well adapted to living in all types of conditions, including extreme ones, and prefer to live in colonies called biofilms.
  • These adaptations, along with others, allow bacteria to be the most abundant life form in all terrestrial and aquatic ecosystems.
  • Other bacteria and archaea are adapted to grow under extreme conditions and are called extremophiles, meaning "lovers of extremes."
  • Because they have specialized adaptations that allow them to live in extreme conditions, many extremophiles cannot survive in moderate environments.
  • Other extremophiles, like radioresistant organisms, do not prefer an extreme environment (in this case, one with high levels of radiation), but have adapted to survive in it.

• Microbial Environments and Microenvironments

  • Clearly, microbes have adapted to extreme and intolerant conditions, and it is this adaptation that has yielded tremendous biological diversity among microorganisms.
  • Therefore, microbes have adapted to fill every ecological niche on the planet.
  • High ionizing radiation (up to 15,000 Gy; as a reference, a mere 5 Gy would kill a human!
  • These evolutionary adaptations have allowed microbial life to extend into much of the Earth's atmosphere, crust, and hydrosphere (the water found over, under, and on the surface of a planet).
  • Microbes, therefore, are not only adapted to their habitat, but also to the immediate environment, thus promoting increased diversity among microbial species within an ecosystem.

• Acute Radiation Damage

  • Acute radiation syndrome or damage describes health effects present within 24 hours of exposure to high amounts of ionizing radiation.
  • Acute radiation syndrome, also known as radiation poisoning, radiation sickness, or radiation toxicity, is a constellation of health effects that are present within 24 hours of exposure to high amounts of ionizing radiation, which can last for several months.
  • Radiation sickness is caused by exposure to a large dose of ionizing radiation over a short period of time, typically greater than about 0.1 Gy/h.
  • The onset and type of symptoms depends on the radiation exposure.
  • These diseases are sometimes referred to as radiation sickness, but they are never included in the term acute radiation syndrome.

• Life Functions

  • An organism is a living system capable of growth, reproduction,metabolism, response to stimuli, adaptation and homeostasis.
  • Nonliving things are not capable of growth, reproduction, response to stimuli, adaptation, or homeostasis.
  • They are capable of reproduction (within a host) and adaptation, but they are not capable of homeostasis or metabolic functions.
  • Many organisms can adapt to intolerance in their environment through seasonal migration, hibernation, or other adaptations.
  • Many microorganisms have evolved adaptations that allow them to survive in zones that are intolerant for most other organisms, such as extreme heat or cold, dehydration, starvation, or high levels of radiation.

• Therapeutic Uses of Radiation

  • Radiation therapy uses ionizing radiation to treat conditions such as hyperthyroidism, cancer, and blood disorders.
  • Radiation therapy involves the application of ionizing radiation to treat conditions such as hyperthyroidism, thyroid cancer, and blood disorders.
  • Ionizing radiation works by damaging the DNA of exposed tissue, leading to cellular death.
  • Radiation therapy is in itself painless.
  • Radiation therapy of the pelvis.

• Medical Imaging and Diagnostics

  • Radiation therapy uses ionizing radiation to treat conditions such as hyperthyroidism, cancer, and blood disorders.
  • Radiation therapy involves the application of ionizing radiation to treat conditions such as hyperthyroidism, thyroid cancer, and blood disorders.
  • Ionizing radiation works by damaging the DNA of exposed tissue, leading to cellular death.
  • Radiation therapy is in itself painless.
  • Radiation therapy of the pelvis.