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Re: Haldane's rule
 
bewnyfur Views: 3,013
Published: 10 years ago
 
This is a reply to # 1,618,876

Re: Haldane's rule


Inter-species mating results in sterile offspring.

That means that "Neanderthals" are actually probably just humans. Showing that this DNA finding may actually disprove certain evolutionary theories.

In short...we still don't know for sure. In other words the Science of standard evolutionary theories is still left wanting. Perhaps some evidence can be manufactured, nice and psyentific like.

**"Haldane's rule relating to hybrids of species and extended to speciation in evolutionary theory is easily stated:

When in the offspring of two different animal races one sex is absent, rare, or sterile, that sex is the heterozygous (heterogametic) sex.

It was originally formulated in 1922 by the British evolutionary biologist J. B. S. Haldane. It is sometimes referred to as Haldane's law.

In many organisms, such as mammals or Drosophila flies, males are the heterogametic sex, in that they have XY sex chromosomes, whereas females are homogametic, with XX chromosomes. However, in some other animals (i.e. birds, butterflies) and plants, the reverse is usually true. Haldane's rule has been shown in a number of different hybrid crosses where either the male or the female is the heterogametic sex.

The fact that hybrid sterility and inviability can evolve due to Haldane's rule in such a vast array of different organisms is quite striking. However, the actual explanation of this phenomenon is rather complicated. Many different hypotheses have been advanced to explain the genetic basis of Haldane's rule.

* The dominance hypothesis: Heterogametic hybrids are affected by all, recessive and dominant, X-linked genes involved in incompatibilities, while homogametic hybrids are only affected by the dominant ones.
* Faster male hypothesis: Male genes evolve faster due to sexua| selection.
* Meiotic drive: In hybrid populations, selfish genetic elements inactivate sperm cells (i.e: A X-linked drive factor inactivates a Y-bearing sperm and vice versa).
* Faster X theory: X-linked have a larger effect in reproductive isolation.

The dominance hypothesis is the most widely accepted explanation of Haldane's rule. However, the individual hypotheses are not mutually exclusive and many causes might potentially act together and cause hybrid sterility and inviability in the heterogametic sex. The faster male hypothesis, for example, receives support from a study in Asian Elephants[1]."
 

 
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