TABLE 1

Y chromosome and/or maternal effects on postzygotic isolation in Drosophila

Species pairY effectaMaternal effectbReferencesc
melanogaster-simulans
InviabilityYes1
Male sterilityYesNo2
simulans-mauritiana
Male sterilityYesNo3
simulans-sechellia
Male sterilityYesNo3
mojavensis-arizonae
Male sterilityYesNo4
pseudoobscura-persimilis
Male sterilityYesNo1
Female “sterility”Yes1
pseudoobscura Bogota-USA
Male sterilityNoNod1
buzzatii-koepferae
Male sterilityNot knownNo1
Male inviabilityNo1
subobscura-madierensis
Male sterilityYesNo1
Female inviabilityYes1
virilis-texana
Male sterilityYesNo1
virilis-novamexicana
Male sterilityYesNo5
virilis-lummei
Male sterilityYesNo6
montana-texana
Female inviabilityYes1
hydei-neohydei
Male sterilityYesNo1
Female sterilityNo1
InviabilityNo1
  • When tallying the results of species crosses (see text), hybridizations were counted as single events; i.e., reciprocal crosses were not tallied separately. Different forms of isolation within a single species cross were, however, counted separately.

  • a Y effects were tallied only in cases of hybrid male sterility. “Yes” indicates that the Y chromosome is involved in at least one direction of the species cross, but not necessarily both. A dash indicates that the entry does not involve hybrid male sterility and so Y effects are not expected.

  • b “Yes” indicates that maternal effects are involved in at least one direction of the species cross. “No” indicates that no maternal effects are known given reasonably thorough genetic analysis; in many cases, however, no explicit test of maternal effects was performed.

  • c Most citations for species crosses are available in reference 1, Coyne and Orr's (1998) recent review (see their Table 1.1). Other references are as follows: 2, Muller and Pontecorvo (1942); 3, Johnson et al. (1993); 4, Zouros et al. (1988); 5, Heikkinen and Lumme (1998); and 6, Falileeva and Mitrofanov (1997).

  • d Contrary to Orr (1989b), this hybridization does not appear to involve maternally acting genes (H. A. Orr, unpublished results).