Ontogeny of Mating and Migration
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What is Ontogeny?
"The development or course of development especially of an individual organism."
-Merriam-Webster(15)
Development of the Mating Mechanism
Utilizing a promiscuous mating system aids in monarch migration. This is because as the number of matings increase, so does the genetic variation that is transferred to the female's offspring. Furthermore, according to the Bateman's Hypothesis, the female's fitness, which means the ability to survive and reproduce viable offspring, increases as her number of mating events also increase (8).
What is the Advantage of Intergenerational Migration (8)?
Allows for the accessibility of seasonal milkweed plants
Avoidance of harsh winter weather
More Genetic variation within offspring
4 Generations & 4 Migration Steps
Generation 1
Generation 2
Click the button to explore an interactive migration video produced by the National Forest Service(4)!
Finding a Mate
Monarchs are a sexually dimorphic species, meaning that the females look different from the males (10).
The males do not need to emit pheromones due to this dimorphism, rather they use a coercive mating system (10).
~ Summer populations: use less aggressive mating tactics because the scent glands decrease the females' struggle.
~ Overwintering Populations: do not use scent glands to calm the females, rather the male utilizes his claspers on the female's abdomen to restrain the female prior to copulation (10).
Males: have smaller veins, 2 black spots on their back wings, and claspers on their abdomen which are utilized to hold the female before copulation(19).
The two black spots are scent glands, which produce a "flowerlike scent" to calm frantic females before copulation after capture. In addition, brush like structures, called anal hair pencils, are used to spread the scent over the female(10).
Females: have thicker veins with no claspers on their abdomen (19).
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Gamete Formation! (19)
Image Credit- https://monarchjointventure.org/images/made/9fb0ebd3ba966afe/femaletract_541_374_all_3_c1_541_374_all_3_c1.gif
Female Monarch Track:
Sperm is stored in spermatheca (joint venture)
Eggs are formed in the ovaries and overioles
Image Credit- https://monarchjointventure.org/images/made/9fb0ebd3ba966afe/testis1_500_223_all_3_c1_500_223_all_3_c1.gif
Male Monarch Testis:
Site of Spermatogenesis