Papilio joanae

Jeff Oliver jeffrey.oliver at
Sat Jan 27 13:32:48 EST 2001

>Felix and others,
>mtDNA seems to introgress pretty readily, moving from one species to
>another if any hybridization occurs. Introgressive hybridization (Edgar
>Anderson first studied it in plants) seems faster for mtDNA than nuclear
>DNA for most eukaryotes. Is this true for papilionids?
The amount of introgression of mtDNA can be affected by the degree to which
Haldane's rule is acting.  Haldane's Rule states: "When in the F1 offspring
of two different animal races one sex is absent, rare, or sterile, that sex
is the heterozygous sex" (Haldane 1922).  Since the females are the
heterogametic sex (they are WZ while males are WW; opposite to humans, in
which males are XY and females are XX), they would be the first to show
reduced viability/fertility IF Haldane's Rule was acting in this case.
Because the mtDNA is only transmitted via the female, and if Haldane's rule
was acting, then the mtDNA would spread LESS readily across hybrid zones
than would nuclear DNA.  The degree to which Haldane's rule is acting in
Papilio crosses varies (Hagen & Scriber 1993, for other references, also see
Sperling 1993).
Jeff Oliver
jeffrey.oliver at
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