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Open Access Publications from the University of California

Variation between Santa Cruz Island and mainland bee specimens

  • Author(s): Thrift, Charles N
  • Seltmann, Katja C
  • et al.

Bees (Hymenoptera: Anthophila) have unique wing venation, which can be used to classify variation between populations of the same species using geometric morphometrics. Here, an application of this method is presented, showing successful distinction between populations of the sweat bee Halictus tripartitus (Hymenoptera: Halictidae) from either island or mainland collections. These two locations are Santa Cruz Island, a 35-kilometer long island about 32 kilometers off the coast of Santa Barbara in the Pacific Ocean, and Santa Barbara, California, a coastal mainland town. 

To analyze wing patterns, forewings were removed, imaged, and annotated with digital landmarks using TPS morphometric software for 9 landmarks. Significant difference between populations is shown with an ANOSIM test (p<0.05), and principal component analysis results are visualized on a biplot. Ongoing work includes adding additional specimens and running new tests, including non-metric multidimensional scaling (NMDS), and “envfit” regression (in R library vegan) to identify the strength and direction each of the 9 landmarks has on the group.

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