Geometric Morphometrics Analysis of Inter-Population Wing Shape Variations in Bats

Abstract

Background: The cryptic diversity of bat fauna in Pakistan demands to incorporate an efficient and reliable approach for morphological species identification. The traditional taxonomic approaches are effective in exploring variations of characters but have proved to be less efficient in quantifying the interspecific and intraspecific differences. Geometric morphometric method has recently act as an efficient tool to analyze the overall changes in shape and size of biological features. The present study is therefore conducted to exploit the use of geometric morphometric methods along with traditional morphological measurements to examine the size and shape differences among four geographically isolated population groups of insectivorous bat species (Pipistrellus coromandra). 
 Methods: Specimens were collected from different locations of Punjab, Pakistan. Twelve well-defined landmarks to quantify the variation in right wing of bats were analyzed using geometric morphometric tools and wing measurements of 5 selected parameters were also taken using traditional morphological measurements. 
 Results: The results of external measurements for wing overlapped for most part among the different studied population groups. Fur colour photographs displayed in the inter-population had shown visible change from dark brown to light brown giving an indication of more morphological differences. Regarding the geometric morphometric results, wing-shape differences were found to dominate in inter-population as compared to intra-population for bats species (Pipistrellus coromandra) which clearly reflects the effects of habitat factors on different populations phenotypically. The wireframe for the first two PCs indicated an overall shape change trend with the displacement of landmark points representing the expansion along the upper wing margins in PC1 compared to PC2. 
 Conclusion: The current study has successfully explored the power of geometric morphometric in reflecting the variations in wing shape among different populations of bats species (Pipistrellus coromandra).