hybrid zone

Examples of hybrid zone in the following topics:

• Hybrid Zones

  • An area where two closely-related species continue to interact and reproduce, forming hybrids, is called a hybrid zone.
  • Over time, the hybrid zone may change depending on the fitness strength and the reproductive barriers of the hybrids .
  • For a hybrid zone to be stable, the offspring produced by the hybrids have to be less fit than members of the parent species.
  • After speciation has occurred, the two separate-but-closely-related species may continue to produce offspring in an area called the hybrid zone.
  • Discuss how the fitness of a hybrid will lead to changes in the hybrid zone over time

• Types of Root Systems and Zones of Growth

  • The root tip has three main zones: a zone of cell division, a zone of elongation, and a zone of maturation.
  • The root tip can be divided into three zones: a zone of cell division, a zone of elongation, and a zone of maturation .
  • All three zones are in approximately the first centimeter of the root tip.
  • A longitudinal view of the root reveals the zones of cell division, elongation, and maturation.
  • Describe the three zones of the root tip and summarize the role of each zone in root growth

• Growth of Bone

  • The zone of maturation and hypertrophy contains chondrocytes that are older and larger than those in the proliferative zone .
  • The zone of calcified matrix, the zone closest to the diaphysis, contains chondrocytes that are dead because the matrix around them has calcified .
  • After the zone of calcified matrix, there is the zone of ossification, which is actually part of the metaphysis .
  • The topmost layer of the epiphysis is the reserve zone.
  • The second zone, the proliferative zone, is where chondrocytes are continually undergoing mitosis.

• Meristems

  • Apical meristems are organized into four zones: (1) the central zone, (2) the peripheral zone, (3) the medullary meristem and (3) the medullary tissue .
  • Surrounding the central zone is the peripheral zone.
  • The rate of cell division in the peripheral zone is higher than that of the central zone.
  • Each zone of the apical meristem has a particular function.
  • Pictured here are the (1) central zone, (2) peripheral zone, (3) medullary meristem and (3) medullary tissue.

• Marine Biomes

  • Each zone has a distinct group of species adapted to the biotic and abiotic conditions particular to that zone.
  • This zone is an extremely variable environment because of tides.
  • The neritic zone extends from the intertidal zone to depths of about 200 m (or 650 ft) at the edge of the continental shelf.
  • Beyond the neritic zone is the open ocean area known as the oceanic zone.
  • There are a variety of invertebrates and fishes found in this zone, but the abyssal zone does not have plants due to the lack of light.

• The Phosphorus Cycle

  • This process is responsible for dead zones in lakes and at the mouths of many major rivers .
  • These zones can be caused by eutrophication, oil spills, dumping of toxic chemicals, and other human activities.
  • The number of dead zones has been increasing for several years; more than 400 of these zones were present as of 2008.
  • One of the worst dead zones is off the coast of the United States in the Gulf of Mexico, where fertilizer runoff from the Mississippi River basin has created a dead zone of over 8,463 square miles.
  • Worldwide, large dead zones are found in coastal areas of high population density.

• Abiotic Factors Influencing Aquatic Biomes

  • The ocean is categorized by several areas or zones .
  • All of the ocean's open water is referred to as the pelagic realm (or zone).
  • The benthic realm (or zone) extends along the ocean bottom from the shoreline to the deepest parts of the ocean floor.
  • At depths greater than 200 m, light cannot penetrate; thus, this is referred to as the aphotic zone.
  • The ocean is divided into different zones based on water depth, light availability, and distance from the shoreline.

• The Evolution of Roots in Seedless Plants

  • The root tip can be divided into three zones: a zone of cell division, a zone of elongation, and a zone of maturation and differentiation .
  • The zone of cell division is closest to the root tip; it is made up of the actively-dividing cells of the root meristem.
  • The zone of elongation is where the newly-formed cells increase in length, thereby lengthening the root.
  • All three zones are in the first centimeter or so of the root tip.
  • A longitudinal view of the root reveals the zones of cell division, elongation, and maturation.

• Physical Maps and Integration with Genetic Maps

  • Physical maps display the physical distance between genes and can be constructed using cytogenetic, radiation hybrid, or sequence mapping.
  • There are three methods used to create a physical map: cytogenetic mapping, radiation hybrid mapping, and sequence mapping.
  • Radiation hybrid mapping uses radiation, such as x-rays, to break the DNA into fragments.
  • Describe the methods used to physically map genes: cytogenetic mapping, radiation hybrid mapping, and sequence mapping

• Garden Pea Characteristics Revealed the Basics of Heredity

  • After gathering and sowing the seeds that resulted from this cross, Mendel found that 100 percent of the F1 hybrid generation had violet flowers.
  • Conventional wisdom at that time would have predicted the hybrid flowers to be pale violet or for hybrid plants to have equal numbers of white and violet flowers.
  • Dominant traits are those that are inherited unchanged in a hybridization.
  • Recessive traits become latent, or disappear, in the offspring of a hybridization.
  • The recessive trait does, however, reappear in the progeny of the hybrid offspring.