Evolution of External Morphology and Flight Muscles in Flightless Stick Insects
Grue, Katherine A.
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The evolution of flight in insects allowed for dispersal, which increased access to resources and mates. Sexual dimorphism is present in many insect species, and generally the females are larger than the males due to the allocation of resources to reproduction. In Extatosoma tiaratum, the female insects are morphologically different from the males in many aspects however, the difference in size between the large wings of the males and the small wings of the females is the most evident. The primary hypothesis was that the degree of sexual dimorphism would be reflected at developmental sequences between male and female. This morphological distinction is not limited to the insects’ external anatomy; the internal flight muscle area varies greatly between sexes and instar stage. This study investigated the external and internal morphological differentiation between sexes and developmental stages of E. tiaratum. E. tiaratum exemplify heterchrony in their wing structures which aided in understanding the sexual dimorphism this species presents. Our results show that there are statistically significant differences between segments, different body regions across the insect, mass and segment size when compared with instar stages of development in both sexes. This difference is why it was speculated that the female insects allocate more resources to reproduction, while the male insects allocate more resources to flight ability.