Q: can two fungal species mate and reproduce new species?

jac55 at cas.org jac55 at cas.org
Tue Nov 28 07:18:11 EST 1995


In article <until.229.000FBD28 at teleport.com>, until at teleport.com writes:
>
>I've been told by a horticulturist that it's possible for two 
>different fungal species to mate and reproduce a third 
>species.  Is this really possible?  What would be the 
>limitations--as in, would the two species have to be closely 
>related? 

     This is pushing the story a bit.  Some fungal species
     are cross-fertile and have progeny that are fertile.  This
     is sometimes made use of in the process called introgression.
     This starts with an interspecific cross followed by several
     rounds of crossing to one of the parents and selection of
     progeny.  Plant breeders have also done this from time to
     time.  
     
     Whether or not you consider the parent organisms separate
     species is going to depend upon your view of fungal taxonomy.
     Some taxonomists may not recognize the parents in a given 
     cross as separate species and therefore may not recognize the 
     progeny as a third species.  A lot also depends upon what
     happens to the chromosomes of the parents upon gamete
     fusion and meiosis.  If both sets of chromosomes can coexist
     in the sexual spore, then I suppose you could end up with
     something that could be considered a new species.  More often,
     you are likely to shed chromosomes and end up with progeny
     carrying just a few genes of the second species.  
     
     Needless to say, you can do things like use auxotrophic and
     resistance markers to select for progeny retaining large
     parts of the "incoming" genome.   



 Would the offspring fungus be able to reproduce 
>itself--or would it be sterile?  What kind of spore-dispersal
>mechanisms would be dominant and passed on to the
>offspring fungus in relation to other spore-dispersal mechanisms? 

     That would depend upon an awful lot of variables, but
     as fertility is generally limited to related species, the
     spore dispersal mechanisms are usually also conserved.
     So you are likely to get a near-normal sexual structure and
     spore maturation and dispersal at reduced levels.
>
>In the two books (_not_ ID books) I have about fungi and their
>spores, nothing like this is mentioned.  So, is this completely
>speculative, or is this possible?

     I suggest that you try searching a biological database
     for the term "introgression."  I don't know how prevalent
     it is.
     
	Alec

 ...aged 40 and still unusual... (Viv Stanshall, in memoriam)
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