On a Wing and a Prayer

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On a Wing and a Prayer

• The Physiology of the Migration of the Monarch
  Butterfly Endemic to the Americas (Danaus
  plexippus)

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North American Groupse.g. of fall migration path

• Latitude Peak Migration
• 45.0 Sept. 4
• 42.5 Sept. 11
• 40.0 Sept. 17
• 37.5 Sept. 24
• 35.0 Sept. 30
• 32.5 Oct. 6
• 30.0 Oct. 13
• 27.5 Oct. 20
• 25.0 Oct. 27
• 9.5 (Mexico) Nov. 14

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Migration Paths(rather than hibernating as other
butterflies)

• One of the best known, most studied North
  American populations (confirmed to migrate) - At
  present, two evolutionary groups migrating
  across North America a western and an eastern
  group which may comprise 10s of millions in the
  migration groups each traveling 2500-3000
  miles
• Questions why do they migrate, how do they
  know where to go (especially when the groups
  migrating south are many generations removed from
  the group that migrated north the previous season)

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The WhereWintering Habitats(reproductive
dormancy or diapause)

• 300 Western Monarch habitats on the California
  coast (Pacific Grove, Monterey area clinging to
  pine and eucalyptus trees remaining quiescent
  (relatively still maintain low metabolic rates)
• 7-8 Eastern Monarch habitats in Mexico (Sierra
  Madre mountain range clinging to oyamal trees)
• Butterflies in each geographical habitat are
  experiencing difficulties (urban expansion, use
  of pesticides, herbicides, logging
  deforestation, exposure to genetically modified
  plants/pollen and occasional temperature
  extremes)

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The WhereSpring Breeding Grounds

• Along the paths and habitats of the milkweed
  plant (where the female lays her eggs and the
  larvae feed)
• As migrate North, the first generation born,
  continue to follow their parents North
• As far north as southern Canada

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The How and the Why

• Some studies Monarchs circadian biological
  clock is like a four dimensional clock knowing
  how to compensate for the hourly and daily
  movement of the sun across the sky while other
  studies suggest they have an internal
  magnetoclinic compass?
• Still other studies suggest that it is the range
  of the milkweed plant that directs the
  migratory path? (co-evolution of the milkweed and
  Monarch?)

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The How and the Why cont

• Day length and temperature changes? Do they move
  in specific directions or take certain pathways?
  How is the migration influenced by the weather
  and are there differences in the migration from
  year to year? Earths magnetic field? Position of
  the sun? Polarization of the suns rays? no
  evidence of migration before 1865! Adaptation in
  less than 150 years?
• Some researchers say groups of Monarchs dont
  migrate e.g. Costa Rica, Australia while other
  researchers say they do?

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