In nature, there are different types of conserved patterns of sex-determining mechanisms which range from male heterogamety (XY) found in the majority of mammals and female heterogamety (ZW) found in most birds to environmental sex determination (ESD) expressed most commonly as temperature sex determination (TSD) found in reptiles and some fish species .
The number of fish species that present male heterogamety compared to female heterogamety is higher .
Berlin, "Single locus sex determination and female heterogamety
in the basket willow (Salix viminalis L.)," Heredity, vol.
niloticus is proposed to display male heterogamety, in contrast to female heterogamety
Gender determination by heterogamety, XY (male heterogamety) or ZW (female heterogamety
), is a well-known system involving 2 genetic factors (Yusa 2007).
Studies of mating signals in birds will be instructive as to whether this discrepancy is specific to Lepidoptera or a consequence of female heterogamety
Among these, Aves and Lepidoptera have both female heterogamety
and hybrid loss of fitness primarily in the females.
We compared taxa with female heterogamety
to their nearest closest relatives with male heterogamety, and asked in which of those sister taxa is female hybrid inviability more common.