Applying Geometric Morphometrics to Identify Bee Species in the Genus (: ) and to Quantify Island-Mainland Variation Within Species Charles Thrift & Katja C. Seltmann Cheadle Center for Biodiversity and Ecological Restoration, University of California – Santa Barbara Contact Information: [email protected] & [email protected]

Introduction Further Methods Discussion Native bees play essential roles in their ecosystems, and accurately tracking Left forewings were removed from each specimen, Homologous Figure 3: Nine wing venation landmarks. The results show that applying geometric morphometrics to wing venation bee diversity is important for understanding ecological change. Yet, identifying slide-mounted, imaged with a DinoXcope wing venation landmarks can be an effective source of identification for species within the bees for research projects and recognizing variation in populations is difficult stereomicroscope digital camera, then edited to the landmarks genus Halictus, and those with more data have more resolution. However, for non-experts. The objectives are: resulting standard picture shown in Figure 2. were plotted variation of island and mainland o Find an accurate and inexpensive method of bee using tpsDig populations within a single species is less identification and detection of population variation software, clear. o Test morphometrics and landmark version 2.31 The landmarking procedure, including homologous wing venation patterns for (Rohlf 2005). photographing bee wings, was identification and variation detection The nine landmarks used (Fig. 3) are easily observed and accomplished remotely and with relatively inexpensive equipment during the o Analyze variation in landmarks between Figure 1: Halictus common in identification. These landmarks were chosen COVID-19 pandemic (Figure 6). This species within one genus rubicundus (left), Figure 2: Original photograph (left) and edited image (right). following the study by Rattanawannee et al. in 2015. Halictus specimens procedure is viable for future exploration o Analyze variation between island and R package geomorph was used to perform a Generalized Figure 6: Remote experimental setup mainland specimens within one species (right). Procrustes Analysis of the landmarks. A principal component analysis (PCA) was then run on the resulting coordinates. of the diversity and variation in bees. In Eigenvalues and principal factors were extracted, and finally, the resulting PCAs were plotted using R package ggbiplot. addition, it may be useful in supporting identifications in localized areas. Methods This study would benefit from a larger sample size, The Cheadle Center for Biodiversity and Ecological Restoration (CCBER) houses Results particularly of the three species most underrepresented the University of California Santa Barbara Invertebrate Zoology Collection. The Plotting by species, five principal factors with eigenvalues (H. ligatus, H. farinosus, and H. rubicundus). Plotting by location for bees used in this study came from that collection, including four species of greater than one were extracted from the PCA analyses. Future directions of study will include adding H. tripartitus, five Total Mainland Island genus Halictus Together, the five components were able to explain 78.00% specimens to the analysis and testing the accuracy of Species principal factors with Specimens Specimens Specimens (Halictidae): H. of the data set the plots by comparing undetermined Halictus eigenvalues greater than Halictus tripartitus 253 171 82 tripartitus, H. ligatus, H. variability. The first specimens’ assigned species to a taxonomist-obtained one were extracted from farinosus, and H. principle component identification. Figure 7: Halictus specimens Halictus ligatus 37 Table 1: abundance of the PCA analyses. rubicundus. Bees were explained 32.2% of Halictus farinosus 5 Halictus specimens Together, the five analyzed. collected between 1954 the variation. Halictus rubicundus 4 components were able Acknowledgements and 2019 (mean 2018, Halictus tripartitus is to explain 72.06% of the median 2019). H. tripartitus was distinguished from Jaime Pawelek, Christopher Evelyn, Yolanda Diao, Taylor Curtis, UCSBees Project, H. tripartitus was collected from data set variability. The most abundant, as shown in Table 1. the other species (https://symbiota.ccber.ucsb.edu) both island and mainland areas. first principle component (Fig. 4) and placed in Mainland specimens were collected explained 26.9% of the the upper right-hand in and around Santa Barbara, a variation. As shown, side. H. farinosus has References coastal mainland town; island Figure 5: Scatterplot of two most island and mainland H. minimal overlap with specimens were collected on Santa influential factors from principal tripartitus specimens Rattanawannee, A., Duangpakdee, O., Rod-im, P., Hepburn, R. (2015). H. ligatus and H. Cruz Island, a 35-kilometer long component analysis of island and have considerable Discrimination of Two Tetragonula (Apidae: Meliponini) Species in Thailand island about 32 kilometers off the rubicundus. mainland Halictus tripartitus, from using Geometric Morphometric Analysis of Wing Venation. Agriculture and Figure 4: Scatterplot of two most nine measured landmarks. overlap (Fig. 5). coast of Santa Barbara in the Pacific Natural Resources, 49(5), 700-710. Ocean, which creates a physical influential factors from principal The average time to process ten bees was 80 minutes, with 60 minutes for component analysis of four Halictus Rolhf, F.J. (2005). tpsDig, 2.31 ed. Department of Ecology and Evolution, State removing wings and imaging, 10 minutes for photo editing, and 10 minutes for barrier between mainland and island species, from nine measured landmarks. University of New York. Stony Brook, NY, USA. populations, shown in Map 1. Map 1: Santa Barbara mainland (black) digital landmarking, however, all steps took more time at the start of the process. and Santa Cruz Island (white).