hybrid sterility

Examples of hybrid sterility in the following topics:

• Reproductive Isolation

  • A postzygotic barrier occurs after zygote formation; this includes organisms that don't survive the embryonic stage and those that are born sterile.
  • Hybrid individuals in many cases cannot form normally in the womb and simply do not survive past the embryonic stages; this is called hybrid inviability.
  • In another postzygotic situation, reproduction leads to the birth and growth of a hybrid that is sterile and unable to reproduce offspring of their own; this is called hybrid sterility.

• 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 .
  • Over time, via a process called hybrid speciation, the hybrids themselves can become a separate species.
  • For a hybrid zone to be stable, the offspring produced by the hybrids have to be less fit than members of the parent species.
  • Discuss how the fitness of a hybrid will lead to changes in the hybrid zone over time

• 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

• Contraception and Birth Control

  • There are many methods of birth control, including barriers to sperm, hormones that prevent ovulation, sterilization procedures, and "natural" methods.
  • The same rate can be achieved through the sterilization procedures of vasectomy in the man or of tubal ligation in the woman, or by using an intrauterine device (IUD).
  • Sterilization is a one-time, permanent, surgical procedure.
  • Tubal ligation or tubectomy is a surgical procedure for sterilization in which a woman's fallopian tubes are clamped and blocked, or severed and sealed; either method prevents eggs from reaching the uterus for fertilization.

• 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.

• Phenotypes and Genotypes

  • Johann Gregor Mendel's (1822–1884) hybridization experiments demonstrate the difference between phenotype and genotype.
  • When true-breeding plants in which one parent had white flowers and one had violet flowers were cross-fertilized, all of the F1 hybrid offspring had violet flowers .
  • That is, the hybrid offspring were phenotypically identical to the true-breeding parent with violet flowers.
  • The resulting hybrids in the F1 generation all had violet flowers.

• Basic Techniques in Protein Analysis

  • These are large-scale adaptations of the basic two-hybrid screen .
  • The premise behind the two-hybrid screen is that most eukaryotic transcription factors have modular activating and binding domains that can still activate transcription even when split into two separate fragments, as long as the fragments are brought within close proximity to each other.
  • If the two proteins of interest bind each other, then the BD and AD will also come together and activate a reporter gene that signals interaction of the two hybrid proteins.
  • Two-hybrid screening is used to determine whether two proteins interact.

• Climate Change and Biodiversity

  • However, in 2006 a hunter shot a wild grizzly-polar bear hybrid known as a grolar bear, the first wild hybrid ever found.

• Speciation

  • Many species are similar enough that hybrid offspring are possible and may often occur in nature, but for the majority of species this rule generally holds.
  • In fact, the presence in nature of hybrids between similar species suggests that they may have descended from a single interbreeding species: the speciation process may not yet be completed.

• Mendel's Laws of Heredity

  • The laws of inheritance were derived by Gregor Mendel, a 19th century monk conducting hybridization experiments in garden peas (Pisum sativum).
  • He described these laws in a two part paper, "Experiments on Plant Hybridization", which was published in 1866.
  • Mendel discovered that by crossing true-breeding white flower and true-breeding purple flower plants, the result was a hybrid offspring.
  • The resulting hybrids in the F1 generation all had violet flowers.