3 years ago



Genetic research to

Genetic research to determine the relationship between monarch populations is ongoing. Lyons et al. (2012) used microsatellite markers to evaluate the genetic structure of the migratory monarch populations in eastern and western North America, as well as the non-migratory populations of Hawaii and New Zealand. They did not find evidence for genetic differentiation between the migratory monarch populations of eastern and western North America, but did find that the migratory populations have diverged genetically from the non-migratory resident populations of Hawaii and New Zealand. However, no taxonomic changes have been made in response to this new research; the monarchs found in Hawaii and New Zealand are still considered to be the same subspecies as the migratory animals of eastern and western North America - D. p. plexippus. This petition requests ESA protection for the subspecies D. p. plexippus. Should future studies published within the time of review of this petition show that the North American migratory populations of monarch constitute a subspecies distinct from nonmigratory populations of Hawaii, New Zealand, or other locations (such as south Florida), then in addition to determining if D. p. plexippus the subspecies should be protected, petitioners also request that the Service evaluate whether any newly identified North American subspecies may warrant federal protection. Monarch ESA Petition 16

DESCRIPTION Photo © Jeffrey E. Belth Figure 1. Female monarch on ovipositing on common milkweed flower bud. The monarch, one of the most recognizable butterflies in North America, has several distinctive morphological characteristics (Ackery and Vane-Wright 1984, pp. 201 – 204, and references therein; Oberhauser and Solensky 2004, Commission for Environmental Cooperation 2008). It is a large butterfly that flies with its orange and black wings held in a “v” shape. The upper surfaces of both the forewing and hindwing have black or dark-brown veins outlining an orange background, with two rows of white and whitish-yellow spots at the margins (cover photo). The dark body is also white-spotted. Underwings have a similar color pattern but the hindwing background color is much lighter, from tan to light orange (Figure 1). The forewing is more angular than the hindwing with an elongated apex that has lighter orange spots near the tip. The wingspan is about 10 cm, with males averaging larger wing sizes than females, although there is substantial variability. Males also have a black scent pouch, or androconium, in the center of each hind wing. Females have thicker dark venation than do males. There appears to be a relationship between wing size and shape and migratory behavior in monarchs. Monarchs east of the Rockies, which migrate longer distances than monarchs from the west, have larger and more angular forewings than their western counterparts on average, even when reared in a common environment, indicating a potential genetic basis for this morphological trait (Altizer and Davis 2010). Monarchs from Hawaii, which do not migrate, have even smaller forewings than western monarchs, although they are just as rounded as in the Monarch ESA Petition 17

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