Sex chromosome evolution in moths and butterflies. Reproduction with a normal XX female would produce anormal female to XY-female, offspring sex ratio. Cytological studies of meiotic recombination in human males. From these, the lengths of the segments separated by the COs can be measured and converted to fractions of the total physical axis length these measurements can be found in Dataset S1.
Incongruent genotypic and phenotypic sex has been documented in Chinook salmon in the Pacific Northwest Nagler et al. Temperature and the progeny sex-ratio in Sciara ocellaris Diptera, Sciaridae. Our data include 30 genera from orders with holocentric chromosomes 25 from Hemiptera, 3 from Dermaptera, and 2 Lepidoptera.
Comp Cytogenet. These effects are described in mathematical detail in SI Appendix. Under haplodiploid sex determination, females develop from diploid fertilized eggs nnand males develop from unfertilized haploid eggs n.
Wolbachia infection frequencies in insects: evidence of a global equilibrium? Hymenoptera There are approximately species of Hymenoptera and it is assumed that all of them have a haplodiploid sex determining system, which has been confirmed in all of the species for which karyotype data is available.
Cold Spring Harbor Perspect Biol. The use of pachytene-stage chromosomes Fig.
Published online Aug XO sex chromosomes are generally less prevalent but have been recorded in 18 out of 53 families, and complex sex chromosome systems have been found in 12 families. CO frequency is simply the number of COs that occur during meiotic prophase as measured either cytologically or from sequence data.
For permissions, please e-mail: journals. Chromosomes are assumed to be of equal size, and COs are assumed always to be evenly spaced along chromosomes.