Extreme differences in size of butterfly chrysalises are normally caused by other reasons that genetic variation. What are some of the other causes?
Butterflies within the same species naturally vary in size.
Natural (good) reasons for size variation:
1. Sex of the chrysalis:
~ Eastern Black Swallowtail female chrysalises are larger than male chrysalises.
~ Monarch male chrysalises are larger than female chrysalises.
2. Genetic reasons:
~ Just as with other animals, sometimes a gene will cause someone to be much smaller or much larger than other of the same species
Other reasons for size variation:
The caterpillar did not eat enough food.
~ Not enough food available
~ Aggressive caterpillars push passive caterpillars from the food
~ Temperature too cold or too hot for caterpillars to eat (they cannot regulate their temperature)
~ Caterpillar diseased, causing lack of appetite
~ Host plant, while acceptable, is not favored by the caterpillar (much like us being offered stale bread)
~ Food contaminated with other substances, changing flavor of food (sometime splashed or spilled or was sprayed on the food)
~ Tender leaves have been eaten and only old tough leaves remain on the plant