Awake! June 22 2004

by badboy 14 Replies latest jw friends

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  El blanko

  What about asexual species

  Humans are not asexual. In my vision, we stand separate.
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  Elsewhere

  A species is no different than a language or dialect.

  They both emerge through geographic isolation and environmental changes.

  http://news.bbc.co.uk/2/hi/science/nature/3790531.stm

  Scientists 'see new species born'

  By Dr David Whitehouse
  BBC News Online science editor

  Scientists at the University of Arizona may have witnessed the birth of a new species for the first time.

  Biologists Laura Reed and Prof Therese Markow made the discovery by observing breeding patterns of fruit flies that live on rotting cacti in deserts.

  The work could help scientists identify the genetic changes that lead one species to evolve into two species.

  The research is published in the Proceedings of the National Academy of Sciences.

  One becomes two

  Whether the two closely related fruit fly populations the scientists studied - Drosophila mojavensis and Drosophila arizonae - represent one species or two is still debated by biologists.

  However, the University of Arizona researchers believe the insects are in the early stages of diverging into separate species.

  The emergence of a new species - speciation - occurs when distinct populations of a species stop reproducing with one another.

  When the two groups can no longer interbreed, they cease exchanging genes and eventually go their own evolutionary ways becoming separate species.

  Though speciation is a crucial element of understanding how evolution works, biologists have not been able to discover the factors that initiate the process.

  In fruit flies there are several examples of mutant genes that prevent different species from breeding but scientists do not know if they are the cause or just a consequence of speciation.

  Sterile males

  In the wild, Drosophila mojavensis and Drosophila arizonae rarely, if ever, interbreed - even though their geographical ranges overlap.

  In the lab, researchers can coax successful breeding but there are complications.

  Drosophila mojavensi s mothers typically produce healthy offspring after mating with Drosophila arizonae males, but when Drosophila arizonae females mate with Drosphila mojavensis males, the resulting males are sterile.

  Laura Reed maintains that such limited capacity for interbreeding indicates that the two groups are on the verge of becoming completely separate species.

  Another finding that adds support to that idea is that in a strain of Drosophila mojavensis from southern California's Catalina Island, mothers always produce sterile males when mated with Drosophila arizonae males.

  Because the hybrid male's sterility depends on the mother's genes, the researchers say the genetic change must be recent.

  Reed has also discovered that only about half the females in the Catalina Island population had the gene (or genes) that confer sterility in the hybrid male offspring.

  However, when she looked at the Drosophila mojavensi s females from other geographic regions, she found that a small fraction of those populations also exhibited the hybrid male sterility.

  The newly begun Drosophila mojavensis genome sequencing project, which will provide a complete roadmap of every gene in the species, will help scientists pin down which genes are involved in speciation.
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  El blanko

  An interesting point about asexual reproduction, is that according to my past reading, the offspring are "genetically identical" (maybe there is new light here ) - which makes the clone ideal to carry on the exact tasks of the parent. Rather than add variation within behaviour, presumably identical genes lend identical character traits. So, an organism will work in exactly the same way as its parent. A relatively insignificant lifeform which performs possibly very relevant tasks which aid our combined well being, may be required to duplicate itself rapidily and precisely.

  Humans when mating add their genes to their children, but the variation in character is far greater of course and allows for a wide variety of personality.
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  Crazy151drinker

  Are we talking Mammals? Insects?? Plants?? Snails?? Trolls??
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  maybesbabies

  I have but one word for ya: Parthenogenesis. Look it up.