Adaptive Value
Image Credit- https://monarchwatch.org/directional-flight/22435956425_28b0f9e428_o.jpg
Adaptive Value:
"The property of a given genotype when compared with other genotypes that confers fitness (q.v.) to an organism in a given environment."
-Oxford Reference(22)
The Value of Mating Through Migration (3)
Intergenerational Migration
-Allows for greater access to resources as different species of milkweed bloom at different seasons.
-Generations 1-4 coincide their migration stretch with the availability of resources in that region.
-Migration allows for each generation to maximize their fitness in a quality environment.
Genetic Variation
-As populations migrate, mating is not restrained to small population size. Western and Eastern population overlap increases genetic variation and therefore increases population fitness.
Overwintering and Reproductive Diapause (19)
Undergoing reproductive diapause makes the monarch migration possible!
-Delaying the release of juvenile hormone prevents monarchs from mating until a suitable environment for their offspring is available(19).
Overwintering is exceptionally difficult on the body of the monarch.
-Many die due to a lack of food and a harsh environment. However, those that do survive are the strongest, passing their exceptional genetics to the next generation(19).
Continuing On!
Watch to view the western monarch population's migration progress(6)!
The Monarch Migration at Risk: (23)
Monarchs struggle to find food as their migration route is invaded by society. Unless they can continue to find food and their milkweed host-plants, the migration will cease to exist. Researchers have sadly observed a major decline in the migration behavior of North American Populations as the butterflies seek out tropical milkweed growing year round. The migration is now in extreme danger of extinction.
Why?
Recent studies have shown that along the California coastline, many monarchs are failing to undergo reproductive diapause due to the growth of tropical milkweed. The result is an entire population adapting to an environment with yearlong food(27).
In an attempt to aid monarchs on their migration, many US citizens have planted tropical milkweed without realizing its detriment to the Monarch population. The migration relies on the cost/benefit of reaching seasonal resources to reproduce. Without seasonal resources, Monarchs will cease migrating and remain close to the year round blooming tropical milkweed(27).
This change in the Monarch's diet could be one of the causes for such a dramatic migratory population decline. The decline in this behavior is most probably a compilation of costs such as new pesticides, infrastructure, and destruction of habitat, society has brought to the Migrating Monarch populations(28).