Sunday, December 26, 2010

Son incest

As I have understood, when a fertile hybrid remains stable and unchanging its genome in their offspring throughout the generations must be considered as a new species with all of the law. I say this so that I will discuss below.

Surely you will be surprised by the title of this article. The truth is that I can not find another more suitable name. How is called the play between a grandfather and his granddaughter? Well that is exactly what they have done two very promiscuous ferns of  Soller Valley in Mallorca. I refer to Asplenium X reichsteinii, the result of retrohybridization between Asplenium majoricum, about which I speak in a previous article and its grandfather, Asplenium fontanum. Just so you understand, the result of this blatant incest is both son and grandson of the same parent, or its father is its grandfather.

Asplenium fontanum (padre)----> X <---- Asplenium petrarchae ssp. bivalens (madre)
      l                                                                                      l
      l                                                                                      l
      l                                                                                     V
....l                            Asplenium protomajoricum (hijo estéril)..............................................................
      l                                                                                     l                                         
      l                                                                                     l
     V                                                                                   V
   X <--------------- Asplenium majoricum ( nieto apogámico fértil)     
Asplenium X reichsteinii ( biznieto incestuoso fértil)

That is, a bracken diploid with a normal genome, Asplenium fontanum, say FF, was hybridized with another fern diploid with a normal genome, Asplenium petrarchae ssp. bivalens, PP, and resulted in a sterile diploid hybrid, the Asplenium protomajoricum, FP, with two mutations that disrupt meiosis and normal sexual reproduction capacity, Apomeiosis and Gametophytic Apomixis, fertile offspring able to generate a double genetic endowment or is tetraploid, PF, from the growth of a somatic cell parthenogenetic tetraploid gametophytes, Asplenium majoricum. This fern subsequently be retrohybridized with its grandfather and gave rise to a triploid incestuous great-grandson, FFP, Asplenium X reichsteinii.

Vigorous Asplenium X reichsteinii, who bears a strong resemblance to its grandfather-father, Asplenium fontanum, with which it shares 66% of its genome. The remaining 33% comes from its great grandmother, Asplenium petrarchae ssp. bivalens.

This son incest, theoretically sterile, producing few aborted spores, but most are perfectly feasible with a budget triploid genome, triplospores and get played back using the same tricks as its hybrid ancestors. That is, cheat, skip the meiosis and sexual reproduction produce normal and parthenogenetic children identical to their mother, or clones of Asplenium X reichsteinii.

Viable triplospores of Asplenium X reichsteinii, view at 400 magnification.

This hybrid  fern is relatively common in the walls of the terraces of the Soller Valley facing north and northwest, which confirms its fertility because a sterile hybrid is usually a solitary individual, anecdotal, that fails to reproduce and die without progeny. Asplenium X reichsteinii should therefore be considered as a new species genetically stable.

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