1. Tiger Swallowtail Pterourus glaucus malefemale

2. What is up with this Tiger Swallowtail? male female

3. An actual specimen: no photoshop!

4. It’s a gynandromorph! “gyn” means “female” “andro” means “male” “morph” means “form” “Gynandromorph” literally means part female and part male.

5. Vocabulary review Zygote: fertilized egg cell Cell differentiation: at some point in cell division, a cell becomes determinate Sex chromosomes: X and Y Humans: XX=female XY= male Lepidoptera: XX=male XY or X=female Non-disjunction: Chromosomes do not detach from each other

6. How does this happen? Normally, in moths & butterflies: XX = Male XY = Female If the butterfly has two or more “X” chromosomes, it will develop as a male. With only one “X” chromosome, it will be a female. In arthropods, the first cell division differentiates left from right. Bilateral gynandromorphs arise by mitotic nondisjunction in the sex chromosomes at this one-two cell stage.

7. XX duplicated XXX male female X

8. Example #2

9. Another Example: Blue Crab male female